| Title: | Quantify and interpret drivers of variation in multilevel gene expression experiments |
|---|---|
| Description: | Quantify and interpret multiple sources of biological and technical variation in gene expression experiments. Uses a linear mixed model to quantify variation in gene expression attributable to individual, tissue, time point, or technical variables. Includes dream differential expression analysis for repeated measures. |
| Authors: | Gabriel Hoffman [aut, cre] |
| Maintainer: | Gabriel E. Hoffman <[email protected]> |
| License: | GPL-2 |
| Version: | 1.37.1 |
| Built: | 2024-11-13 03:33:07 UTC |
| Source: | https://github.com/bioc/variancePartition |
Apply pre-specified sample weights by scaling existing precision weights
applyQualityWeights(vobj, weights)applyQualityWeights(vobj, weights)
vobj |
|
weights |
sample level weights |
Apply pre-specified sample-level weights to the existing precision weights estimated from the data. While the limma::voomWithQualityWeights function of Lui et al. (2015) estimates the sample-level weights from voom fit, here the weights are fixed beforehand.
Liu R, Holik AZ, Su S, Jansz N, Chen K, Leong HS, Blewitt ME, Asselin-Labat M, Smyth GK, Ritchie ME (2015). “Why weight? Modelling sample and observational level variability improves power in RNA-seq analyses.” Nucleic acids research, 43(15), e97–e97.
limma::voomWithQualityWeights
Convert varPartResults to data.frame
## S3 method for class 'varPartResults' as.data.frame(x, row.names = NULL, optional = FALSE, ...)## S3 method for class 'varPartResults' as.data.frame(x, row.names = NULL, optional = FALSE, ...)
x |
varPartResults |
row.names |
pass thru to generic |
optional |
pass thru to generic |
... |
other arguments. |
data.frame
# load library # library(variancePartition) # load simulated data: # geneExpr: matrix of gene expression values # info: information/metadata about each sample data(varPartData) # Specify variables to consider # Age is continuous so we model it as a fixed effect # Individual and Tissue are both categorical, so we model them as random effects form <- ~ Age + (1 | Individual) + (1 | Tissue) # Fit model varPart <- fitExtractVarPartModel(geneExpr[1:5, ], form, info) # convert to matrix as.data.frame(varPart)# load library # library(variancePartition) # load simulated data: # geneExpr: matrix of gene expression values # info: information/metadata about each sample data(varPartData) # Specify variables to consider # Age is continuous so we model it as a fixed effect # Individual and Tissue are both categorical, so we model them as random effects form <- ~ Age + (1 | Individual) + (1 | Tissue) # Fit model varPart <- fitExtractVarPartModel(geneExpr[1:5, ], form, info) # convert to matrix as.data.frame(varPart)
Convert varPartResults to matrix
## S4 method for signature 'varPartResults' as.matrix(x, ...)## S4 method for signature 'varPartResults' as.matrix(x, ...)
x |
varPartResults |
... |
other arguments. |
matrix
# load library # library(variancePartition) # load simulated data: # geneExpr: matrix of gene expression values # info: information/metadata about each sample data(varPartData) # Specify variables to consider # Age is continuous so we model it as a fixed effect # Individual and Tissue are both categorical, so we model them as random effects form <- ~ Age + (1 | Individual) + (1 | Tissue) # Fit model varPart <- fitExtractVarPartModel(geneExpr[1:5, ], form, info) # convert to matrix as.matrix(varPart)# load library # library(variancePartition) # load simulated data: # geneExpr: matrix of gene expression values # info: information/metadata about each sample data(varPartData) # Specify variables to consider # Age is continuous so we model it as a fixed effect # Individual and Tissue are both categorical, so we model them as random effects form <- ~ Age + (1 | Individual) + (1 | Tissue) # Fit model varPart <- fitExtractVarPartModel(geneExpr[1:5, ], form, info) # convert to matrix as.matrix(varPart)
Augment observed read counts with prior count since log of zero counts is undefined. The prior count added to each sample is scaled so that no variance is introduced
augmentPriorCount( counts, lib.size = colSums2(counts), prior.count = 0.5, scaledByLib = FALSE )augmentPriorCount( counts, lib.size = colSums2(counts), prior.count = 0.5, scaledByLib = FALSE )
counts |
matrix of read counts with genes as rows and samples as columns |
lib.size |
library sizes, the sum of all ready for each sample |
prior.count |
average prior count added to each sample. |
scaledByLib |
if |
Adding prior counts removes the issue of evaluating the log of zero counts, and stabilizes the log transform when counts are very small. However, adding a constant prior count to all samples can introduced an artifact. Consider two samples each with zero counts for a given gene, but one as a library size of 1k and the other of 50k. After applying the prior count values become pc / 1k and pc / 50k. It appears that there is variance in the expression of this gene, even though no counts are observed. This is driven only by variation in the library size, which does not reflect biology. This issue is most problematic for small counts.
Instead, we make the reasonable assumption that a gene does not have expression variance unless supported sufficiently by counts in the numerator. Consider adding a different prior count to each sample so that genes with zero counts end up woth zero variance. This corresponds to adding prior.count * lib.size[i] / mean(lib.size) to sample i.
This is done in the backend of edgeR::cpm(), but this function allows users to apply it more generally.
matrix with augmented counts
edgeR::cpm()
library(edgeR) data(varPartDEdata) # normalize RNA-seq counts dge <- DGEList(counts = countMatrix) dge <- calcNormFactors(dge) countsAugmented <- augmentPriorCount( dge$counts, dge$samples$lib.size, 1)library(edgeR) data(varPartDEdata) # normalize RNA-seq counts dge <- DGEList(counts = countMatrix) dge <- calcNormFactors(dge) countsAugmented <- augmentPriorCount( dge$counts, dge$samples$lib.size, 1)
BIC from model fit
## S3 method for class 'MArrayLM' BIC(object, vobj, ...)## S3 method for class 'MArrayLM' BIC(object, vobj, ...)
object |
result of |
vobj |
|
... |
See |
BIC from model fit using edf
## S3 method for class 'MArrayLM2' BIC(object, vobj, ...)## S3 method for class 'MArrayLM2' BIC(object, vobj, ...)
object |
result of |
vobj |
|
... |
See |
Compute fraction of variation attributable to each variable in regression model. Also interpretable as the intra-class correlation after correcting for all other variables in the model.
calcVarPart(fit, returnFractions = TRUE, ...) ## S4 method for signature 'lm' calcVarPart(fit, returnFractions = TRUE, ...) ## S4 method for signature 'lmerMod' calcVarPart(fit, returnFractions = TRUE, ...) ## S4 method for signature 'glm' calcVarPart(fit, returnFractions = TRUE, ...) ## S4 method for signature 'negbin' calcVarPart(fit, returnFractions = TRUE, ...) ## S4 method for signature 'glmerMod' calcVarPart(fit, returnFractions = TRUE, ...)calcVarPart(fit, returnFractions = TRUE, ...) ## S4 method for signature 'lm' calcVarPart(fit, returnFractions = TRUE, ...) ## S4 method for signature 'lmerMod' calcVarPart(fit, returnFractions = TRUE, ...) ## S4 method for signature 'glm' calcVarPart(fit, returnFractions = TRUE, ...) ## S4 method for signature 'negbin' calcVarPart(fit, returnFractions = TRUE, ...) ## S4 method for signature 'glmerMod' calcVarPart(fit, returnFractions = TRUE, ...)
fit |
model fit from lm() or lmer() |
returnFractions |
default: TRUE. If TRUE return fractions that sum to 1. Else return unscaled variance components. |
... |
additional arguments (not currently used) |
For linear model, variance fractions are computed based on the sum of squares explained by each component. For the linear mixed model, the variance fractions are computed by variance component estimates for random effects and sum of squares for fixed effects.
For a generalized linear model, the variance fraction also includes the contribution of the link function so that fractions are reported on the linear (i.e. link) scale rather than the observed (i.e. response) scale. For linear regression with an identity link, fractions are the same on both scales. But for logit or probit links, the fractions are not well defined on the observed scale due to the transformation imposed by the link function.
The variance implied by the link function is the variance of the corresponding distribution:
logit -> logistic distribution -> variance is pi^2/3
probit -> standard normal distribution -> variance is 1
For the Poisson distribution with rate , the variance is .
For the negative binomial distribution with rate and shape , the variance is .
Variance decomposition is reviewed by Nakagawa and Schielzeth (2012), and expanded to other GLMs by Nakagawa, Johnson and Schielzeth (2017). See McKelvey and Zavoina (1975) for early work on applying to GLMs. Also see DeMaris (2002)
We note that Nagelkerke's pseudo R^2 evaluates the variance explained by the full model. Instead, a variance partitioning approach evaluates the variance explained by each term in the model, so that the sum of each systematic plus random term sums to 1 (Hoffman and Schadt, 2016; Nakagawa and Schielzeth, 2012).
fraction of variance explained / ICC for each variable in the regression model
Nakagawa S, Johnson PC, Schielzeth H (2017). “The coefficient of determination R 2 and intra-class correlation coefficient from generalized linear mixed-effects models revisited and expanded.” Journal of the Royal Society Interface, 14(134), 20170213.
Nakagawa S, Schielzeth H (2013). “A general and simple method for obtaining R2 from generalized linear mixed-effects models.” Methods in ecology and evolution, 4(2), 133–142.
McKelvey RD, Zavoina W (1975). “A statistical model for the analysis of ordinal level dependent variables.” Journal of mathematical sociology, 4(1), 103–120.
DeMaris A (2002). “Explained variance in logistic regression: A Monte Carlo study of proposed measures.” Sociological Methods & Research, 31(1), 27–74.
Hoffman GE, Schadt EE (2016). “variancePartition: interpreting drivers of variation in complex gene expression studies.” BMC bioinformatics, 17(1), 1–13.
library(lme4) data(varPartData) # Linear mixed model fit <- lmer(geneExpr[1, ] ~ (1 | Tissue) + Age, info) calcVarPart(fit) # Linear model # Note that the two models produce slightly different results # This is expected: they are different statistical estimates # of the same underlying value fit <- lm(geneExpr[1, ] ~ Tissue + Age, info) calcVarPart(fit)library(lme4) data(varPartData) # Linear mixed model fit <- lmer(geneExpr[1, ] ~ (1 | Tissue) + Age, info) calcVarPart(fit) # Linear model # Note that the two models produce slightly different results # This is expected: they are different statistical estimates # of the same underlying value fit <- lm(geneExpr[1, ] ~ Tissue + Age, info) calcVarPart(fit)
Assess correlation between all pairs of variables in a formula
canCorPairs(formula, data, showWarnings = TRUE)canCorPairs(formula, data, showWarnings = TRUE)
formula |
standard additive linear model formula (doesn't support random effects currently, so just change the syntax) |
data |
data.frame with the data for the variables in the formula |
showWarnings |
default to true |
Canonical Correlation Analysis (CCA) is similar to correlation between two vectors, except that CCA can accommodate matricies as well. For a pair of variables, canCorPairs assesses the degree to which they co-vary and contain the same information. Variables in the formula can be a continuous variable or a discrete variable expanded to a matrix (which is done in the backend of a regression model). For a pair of variables, canCorPairs uses CCA to compute the correlation between these variables and returns the pairwise correlation matrix.
Statistically, let rho be the array of correlation values returned by the standard R function cancor to compute CCA. canCorPairs() returns sqrt(mean(rho^2)), which is the fraction of the maximum possible correlation. When comparing a two vectors, or a vector and a matrix, this gives the save value as the absolute correlation. When comparing two sets of categorical variables (i.e. expanded to two matricies), this is equivalent to Cramer's V statistic.
Note that CCA returns correlation values between 0 and 1.
Matrix of correlation values between all pairs of variables.
# load library # library(variancePartition) # load simulated data: data(varPartData) # specify formula form <- ~ Individual + Tissue + Batch + Age + Height # Compute Canonical Correlation Analysis (CCA) # between all pairs of variables # returns absolute correlation value C <- canCorPairs(form, info) # Plot correlation matrix plotCorrMatrix(C)# load library # library(variancePartition) # load simulated data: data(varPartData) # specify formula form <- ~ Individual + Tissue + Batch + Age + Height # Compute Canonical Correlation Analysis (CCA) # between all pairs of variables # returns absolute correlation value C <- canCorPairs(form, info) # Plot correlation matrix plotCorrMatrix(C)
For each gene, classify a series of related t-statistics as up, down or not significant.
classifyTestsF(object, ...)classifyTestsF(object, ...)
object |
numeric matrix of t-statistics or an 'MArrayLM2' object from which the t-statistics may be extracted. |
... |
additional arguments |
Works like limma::classifyTestsF, except object can have a list of covariance matrices object$cov.coefficients.list, instead of just one in object$cov.coefficients
limma::classifyTestsF
For each gene, classify a series of related t-statistics as up, down or not significant.
## S4 method for signature 'MArrayLM2' classifyTestsF( object, cor.matrix = NULL, df = Inf, p.value = 0.01, fstat.only = FALSE )## S4 method for signature 'MArrayLM2' classifyTestsF( object, cor.matrix = NULL, df = Inf, p.value = 0.01, fstat.only = FALSE )
object |
numeric matrix of t-statistics or an 'MArrayLM2' object from which the t-statistics may be extracted. |
cor.matrix |
covariance matrix of each row of t-statistics. Defaults to the identity matrix. |
df |
numeric vector giving the degrees of freedom for the t-statistics. May have length 1 or length equal to the number of rows of tstat. |
p.value |
numeric value between 0 and 1 giving the desired size of the test |
fstat.only |
logical, if 'TRUE' then return the overall F-statistic as for 'FStat' instead of classifying the test results |
Works like limma::classifyTestsF, except object can have a list of covariance matrices object$cov.coefficients.list, instead of just one in object$cov.coefficients
limma::classifyTestsF
Collinearity score for a regression model indicating if variables are too highly correlated to give meaningful results
colinearityScore(fit)colinearityScore(fit)
fit |
regression model fit from lm() or lmer() |
Returns the collinearity score between 0 and 1, where a score > 0.999 means the degree of collinearity is too high. This function reports the correlation matrix between coefficient estimates for fixed effects. The collinearity score is the maximum absolute correlation value of this matrix. Note that the values are the correlation between the parameter estimates, and not between the variables themselves.
# load library # library(variancePartition) # load simulated data: data(varPartData) # form <- ~ Age + (1 | Individual) + (1 | Tissue) res <- fitVarPartModel(geneExpr[1:10, ], form, info) # evaluate the collinearity score on the first model fit # this reports the correlation matrix between coefficients estimates # for fixed effects # the collinearity score is the maximum absolute correlation value # If the collinearity score > .999 then the variance partition # estimates may be problematic # In that case, a least one variable should be omitted colinearityScore(res[[1]])# load library # library(variancePartition) # load simulated data: data(varPartData) # form <- ~ Age + (1 | Individual) + (1 | Tissue) res <- fitVarPartModel(geneExpr[1:10, ], form, info) # evaluate the collinearity score on the first model fit # this reports the correlation matrix between coefficients estimates # for fixed effects # the collinearity score is the maximum absolute correlation value # If the collinearity score > .999 then the variance partition # estimates may be problematic # In that case, a least one variable should be omitted colinearityScore(res[[1]])
Given a model fit for each features, residuals are computed and transformed based on an absolute value or squaring transform.
deviation(fit, method = c("AD", "SQ"), scale = c("leverage", "none")) ## S4 method for signature 'MArrayLM' deviation(fit, method = c("AD", "SQ"), scale = c("leverage", "none"))deviation(fit, method = c("AD", "SQ"), scale = c("leverage", "none")) ## S4 method for signature 'MArrayLM' deviation(fit, method = c("AD", "SQ"), scale = c("leverage", "none"))
fit |
model fit from |
method |
transform the residuals using absolute deviation ("AD") or squared deviation ("SQ"). |
scale |
scale each observation by "leverage", or no scaling ("none") |
matrix of deviations from expection for each observation
diffVar()
# library(variancePartition) library(edgeR) data(varPartDEdata) # filter genes by number of counts isexpr <- rowSums(cpm(countMatrix) > 0.1) >= 5 # Standard usage of limma/voom dge <- DGEList(countMatrix[isexpr, ]) dge <- calcNormFactors(dge) # make this vignette faster by analyzing a subset of genes dge <- dge[1:1000, ] # regression formula form <- ~Disease # estimate precision weights vobj <- voomWithDreamWeights(dge, form, metadata) # fit dream model fit <- dream(vobj, form, metadata) fit <- eBayes(fit) # Compute deviation from expection for each observation # using model residuals z <- deviation(fit) z[1:4, 1:4]# library(variancePartition) library(edgeR) data(varPartDEdata) # filter genes by number of counts isexpr <- rowSums(cpm(countMatrix) > 0.1) >= 5 # Standard usage of limma/voom dge <- DGEList(countMatrix[isexpr, ]) dge <- calcNormFactors(dge) # make this vignette faster by analyzing a subset of genes dge <- dge[1:1000, ] # regression formula form <- ~Disease # estimate precision weights vobj <- voomWithDreamWeights(dge, form, metadata) # fit dream model fit <- dream(vobj, form, metadata) fit <- eBayes(fit) # Compute deviation from expection for each observation # using model residuals z <- deviation(fit) z[1:4, 1:4]
Test the association between a covariate of interest and the response's deviation from expectation.
diffVar( fit, method = c("AD", "SQ"), scale = c("leverage", "none"), BPPARAM = SerialParam(), ... ) ## S4 method for signature 'MArrayLM' diffVar( fit, method = c("AD", "SQ"), scale = c("leverage", "none"), BPPARAM = SerialParam(), ... )diffVar( fit, method = c("AD", "SQ"), scale = c("leverage", "none"), BPPARAM = SerialParam(), ... ) ## S4 method for signature 'MArrayLM' diffVar( fit, method = c("AD", "SQ"), scale = c("leverage", "none"), BPPARAM = SerialParam(), ... )
fit |
model fit from |
method |
transform the residuals using absolute deviation ("AD") or squared deviation ("SQ"). |
scale |
scale each observation by "leverage", or no scaling ("none") |
BPPARAM |
parameters for parallel evaluation |
... |
other parameters passed to |
This method performs a test of differential variance between two subsets of the data, in a way that generalizes to multiple categories, continuous variables and metrics of spread beyond variance. For the two category test, this method is simular to Levene's test. This model was adapted from Phipson, et al (2014), extended to linear mixed models, and adapted to be compatible with dream().
This method is composed of multiple steps where 1) a typical linear (mixed) model is fit with dream(), 2) residuals are computed and transformed based on an absolute value or squaring transform, 3) a second regression is performed with dream() to test if a variable is associated with increased deviation from expectation. Both regression take advantage of the dream() linear (mixed) modelling framework followed by empirical Bayes shrinkage that extends the limma::voom() framework.
Note that diffVar() takes the results of the first regression as a parameter to use as a starting point.
MArrayLM object storing differential results to be passed to topTable()
Phipson B, Oshlack A (2014). “DiffVar: a new method for detecting differential variability with application to methylation in cancer and aging.” Genome biology, 15(9), 1–16.
missMethyl::diffVar(), car::leveneTest()
# library(variancePartition) library(edgeR) data(varPartDEdata) # filter genes by number of counts isexpr <- rowSums(cpm(countMatrix) > 0.1) >= 5 # Standard usage of limma/voom dge <- DGEList(countMatrix[isexpr, ]) dge <- calcNormFactors(dge) # make this vignette faster by analyzing a subset of genes dge <- dge[1:1000, ] # regression formula form <- ~Disease # estimate precision weights vobj <- voomWithDreamWeights(dge, form, metadata) # fit dream model fit <- dream(vobj, form, metadata) fit <- eBayes(fit) # fit differential variance model res <- diffVar(fit) # extract results for differential variance based on Disease topTable(res, coef = "Disease1", number = 3) # Box plot of top hit # Since ASCL3 has a negative logFC, # the deviation from expectation is *smaller* in # Disease==1 compared to baseline. gene <- "ENST00000325884.1 gene=ASCL3" boxplot(vobj$E[gene, ] ~ metadata$Disease, main = gene)# library(variancePartition) library(edgeR) data(varPartDEdata) # filter genes by number of counts isexpr <- rowSums(cpm(countMatrix) > 0.1) >= 5 # Standard usage of limma/voom dge <- DGEList(countMatrix[isexpr, ]) dge <- calcNormFactors(dge) # make this vignette faster by analyzing a subset of genes dge <- dge[1:1000, ] # regression formula form <- ~Disease # estimate precision weights vobj <- voomWithDreamWeights(dge, form, metadata) # fit dream model fit <- dream(vobj, form, metadata) fit <- eBayes(fit) # fit differential variance model res <- diffVar(fit) # extract results for differential variance based on Disease topTable(res, coef = "Disease1", number = 3) # Box plot of top hit # Since ASCL3 has a negative logFC, # the deviation from expectation is *smaller* in # Disease==1 compared to baseline. gene <- "ENST00000325884.1 gene=ASCL3" boxplot(vobj$E[gene, ] ~ metadata$Disease, main = gene)
Fit linear mixed model for differential expression and preform hypothesis test on fixed effects as specified in the contrast matrix L
dream( exprObj, formula, data, L, ddf = c("adaptive", "Satterthwaite", "Kenward-Roger"), useWeights = TRUE, control = vpcontrol, hideErrorsInBackend = FALSE, REML = TRUE, BPPARAM = SerialParam(), ... )dream( exprObj, formula, data, L, ddf = c("adaptive", "Satterthwaite", "Kenward-Roger"), useWeights = TRUE, control = vpcontrol, hideErrorsInBackend = FALSE, REML = TRUE, BPPARAM = SerialParam(), ... )
exprObj |
matrix of expression data (g genes x n samples), or |
formula |
specifies variables for the linear (mixed) model. Must only specify covariates, since the rows of exprObj are automatically used as a response. e.g.: |
data |
data.frame with columns corresponding to formula |
L |
contrast matrix specifying a linear combination of fixed effects to test |
ddf |
Specifiy "Satterthwaite" or "Kenward-Roger" method to estimate effective degress of freedom for hypothesis testing in the linear mixed model. Note that Kenward-Roger is more accurate, but is *much* slower. Satterthwaite is a good enough approximation for most datasets. "adaptive" (Default) uses KR for <= 20 samples. |
useWeights |
if TRUE, analysis uses heteroskedastic error estimates from |
control |
control settings for |
hideErrorsInBackend |
default FALSE. If TRUE, hide errors in |
REML |
use restricted maximum likelihood to fit linear mixed model. default is TRUE. See Details. |
BPPARAM |
parameters for parallel evaluation |
... |
Additional arguments for |
A linear (mixed) model is fit for each gene in exprObj, using formula to specify variables in the regression (Hoffman and Roussos, 2021). If categorical variables are modeled as random effects (as is recommended), then a linear mixed model us used. For example if formula is ~ a + b + (1|c), then the model is
fit <- lmer( exprObj[j,] ~ a + b + (1|c), data=data)
useWeights=TRUE causes weightsMatrix[j,] to be included as weights in the regression model.
Note: Fitting the model for 20,000 genes can be computationally intensive. To accelerate computation, models can be fit in parallel using BiocParallel to run code in parallel. Parallel processing must be enabled before calling this function. See below.
The regression model is fit for each gene separately. Samples with missing values in either gene expression or metadata are omitted by the underlying call to lmer.
Hypothesis tests and degrees of freedom are producted by lmerTest and pbkrtest pacakges
While REML=TRUE is required by lmerTest when ddf='Kenward-Roger', ddf='Satterthwaite' can be used with REML as TRUE or FALSE. Since the Kenward-Roger method gave the best power with an accurate control of false positive rate in our simulations, and since the Satterthwaite method with REML=TRUE gives p-values that are slightly closer to the Kenward-Roger p-values, REML=TRUE is the default. See Vignette "3) Theory and practice of random effects and REML"
MArrayLM2 object (just like MArrayLM from limma), and the directly estimated p-value (without eBayes)
Hoffman GE, Roussos P (2021). “dream: Powerful differential expression analysis for repeated measures designs.” Bioinformatics, 37(2), 192–201.
# library(variancePartition) # load simulated data: # geneExpr: matrix of *normalized* gene expression values # info: information/metadata about each sample data(varPartData) form <- ~ Batch + (1 | Individual) + (1 | Tissue) # Fit linear mixed model for each gene # run on just 10 genes for time # NOTE: dream() runs on *normalized* data fit <- dream(geneExpr[1:10, ], form, info) fit <- eBayes(fit) # view top genes topTable(fit, coef = "Batch2", number = 3) # get contrast matrix testing if the coefficient for Batch3 is # different from coefficient for Batch2 # Name this comparison as 'compare_3_2' # The variable of interest must be a fixed effect L <- makeContrastsDream(form, info, contrasts = c(compare_3_2 = "Batch3 - Batch2")) # plot contrasts plotContrasts(L) # Fit linear mixed model for each gene # run on just 10 genes for time fit2 <- dream(geneExpr[1:10, ], form, info, L) fit2 <- eBayes(fit2) # view top genes for this contrast topTable(fit2, coef = "compare_3_2", number = 3) # Parallel processing using multiple cores with reduced memory usage param <- SnowParam(4, "SOCK", progressbar = TRUE) fit3 <- dream(geneExpr[1:10, ], form, info, L, BPPARAM = param) fit3 <- eBayes(fit3) # Fit fixed effect model for each gene # Use lmFit in the backend form <- ~Batch fit4 <- dream(geneExpr[1:10, ], form, info, L) fit4 <- eBayes(fit4) # view top genes topTable(fit4, coef = "compare_3_2", number = 3) # Compute residuals using dream residuals(fit4)[1:4, 1:4]# library(variancePartition) # load simulated data: # geneExpr: matrix of *normalized* gene expression values # info: information/metadata about each sample data(varPartData) form <- ~ Batch + (1 | Individual) + (1 | Tissue) # Fit linear mixed model for each gene # run on just 10 genes for time # NOTE: dream() runs on *normalized* data fit <- dream(geneExpr[1:10, ], form, info) fit <- eBayes(fit) # view top genes topTable(fit, coef = "Batch2", number = 3) # get contrast matrix testing if the coefficient for Batch3 is # different from coefficient for Batch2 # Name this comparison as 'compare_3_2' # The variable of interest must be a fixed effect L <- makeContrastsDream(form, info, contrasts = c(compare_3_2 = "Batch3 - Batch2")) # plot contrasts plotContrasts(L) # Fit linear mixed model for each gene # run on just 10 genes for time fit2 <- dream(geneExpr[1:10, ], form, info, L) fit2 <- eBayes(fit2) # view top genes for this contrast topTable(fit2, coef = "compare_3_2", number = 3) # Parallel processing using multiple cores with reduced memory usage param <- SnowParam(4, "SOCK", progressbar = TRUE) fit3 <- dream(geneExpr[1:10, ], form, info, L, BPPARAM = param) fit3 <- eBayes(fit3) # Fit fixed effect model for each gene # Use lmFit in the backend form <- ~Batch fit4 <- dream(geneExpr[1:10, ], form, info, L) fit4 <- eBayes(fit4) # view top genes topTable(fit4, coef = "compare_3_2", number = 3) # Compute residuals using dream residuals(fit4)[1:4, 1:4]
Scaled chi-square density using a gamma distribution
dscchisq(x, a, b)dscchisq(x, a, b)
x |
vector of quantiles. |
a |
scale |
b |
degrees of freedom |
eBayes for result of linear mixed model for with dream() using residual degrees of freedom approximated with rdf.merMod()
## S4 method for signature 'MArrayLM2' eBayes( fit, proportion = 0.01, stdev.coef.lim = c(0.1, 4), trend = FALSE, robust = FALSE, winsor.tail.p = c(0.05, 0.1) )## S4 method for signature 'MArrayLM2' eBayes( fit, proportion = 0.01, stdev.coef.lim = c(0.1, 4), trend = FALSE, robust = FALSE, winsor.tail.p = c(0.05, 0.1) )
fit |
fit |
proportion |
proportion |
stdev.coef.lim |
stdev.coef.lim |
trend |
trend |
robust |
robust |
winsor.tail.p |
winsor.tail.p |
results of eBayes using approximated residual degrees of freedom
dream rdf.merMod
Compute effective sample size based on correlation structure in linear mixed model
ESS(fit, method = "full") ## S4 method for signature 'lmerMod' ESS(fit, method = "full")ESS(fit, method = "full") ## S4 method for signature 'lmerMod' ESS(fit, method = "full")
fit |
model fit from lmer() |
method |
"full" uses the full correlation structure of the model. The "approximate" method makes the simplifying assumption that the study has a mean of m samples in each of k groups, and computes m based on the study design. When the study design is evenly balanced (i.e. the assumption is met), this gives the same results as the "full" method. |
Effective sample size calculations are based on:
Liu, G., and Liang, K. Y. (1997). Sample size calculations for studies with correlated observations. Biometrics, 53(3), 937-47.
"full" method: if
is the variance-covariance matrix of Y, the response, based on the covariate x, then the effective sample size corresponding to this covariate is
. In R notation, this is: sum(solve(V_x)). In practice, this can be evaluted as sum(w), where R
"approximate" method: Letting m be the mean number of samples per group,
be the number of groups, and
be the intraclass correlation, the effective sample size is
Note that these values are equal when there are exactly m samples in each group. If m is only an average then this an approximation.
effective sample size for each random effect in the model
library(lme4) data(varPartData) # Linear mixed model fit <- lmer(geneExpr[1, ] ~ (1 | Individual) + (1 | Tissue) + Age, info) # Effective sample size ESS(fit)library(lme4) data(varPartData) # Linear mixed model fit <- lmer(geneExpr[1, ] ~ (1 | Individual) + (1 | Tissue) + Age, info) # Effective sample size ESS(fit)
Extract variance statistics from list of models fit with lm() or lmer()
extractVarPart(modelList, ...)extractVarPart(modelList, ...)
modelList |
list of |
... |
other arguments |
data.frame of fraction of variance explained by each variable, after correcting for all others.
# library(variancePartition) library(BiocParallel) # load simulated data: # geneExpr: matrix of gene expression values # info: information/metadata about each sample data(varPartData) # Specify variables to consider # Age is continuous so we model it as a fixed effect # Individual and Tissue are both categorical, so we model them as random effects form <- ~ Age + (1 | Individual) + (1 | Tissue) # Step 1: fit linear mixed model on gene expresson # If categoritical variables are specified, a linear mixed model is used # If all variables are modeled as continuous, a linear model is used # each entry in results is a regression model fit on a single gene # Step 2: extract variance fractions from each model fit # for each gene, returns fraction of variation attributable to each variable # Interpretation: the variance explained by each variable # after correction for all other variables varPart <- fitExtractVarPartModel(geneExpr, form, info) # violin plot of contribution of each variable to total variance plotVarPart(sortCols(varPart)) # Advanced: # Fit model and extract variance in two separate steps # Step 1: fit model for each gene, store model fit for each gene in a list results <- fitVarPartModel(geneExpr, form, info) # Step 2: extract variance fractions varPart <- extractVarPart(results)# library(variancePartition) library(BiocParallel) # load simulated data: # geneExpr: matrix of gene expression values # info: information/metadata about each sample data(varPartData) # Specify variables to consider # Age is continuous so we model it as a fixed effect # Individual and Tissue are both categorical, so we model them as random effects form <- ~ Age + (1 | Individual) + (1 | Tissue) # Step 1: fit linear mixed model on gene expresson # If categoritical variables are specified, a linear mixed model is used # If all variables are modeled as continuous, a linear model is used # each entry in results is a regression model fit on a single gene # Step 2: extract variance fractions from each model fit # for each gene, returns fraction of variation attributable to each variable # Interpretation: the variance explained by each variable # after correction for all other variables varPart <- fitExtractVarPartModel(geneExpr, form, info) # violin plot of contribution of each variable to total variance plotVarPart(sortCols(varPart)) # Advanced: # Fit model and extract variance in two separate steps # Step 1: fit model for each gene, store model fit for each gene in a list results <- fitVarPartModel(geneExpr, form, info) # Step 2: extract variance fractions varPart <- extractVarPart(results)
Fit linear (mixed) model to estimate contribution of multiple sources of variation while simultaneously correcting for all other variables. Report fraction of variance attributable to each variable
fitExtractVarPartModel( exprObj, formula, data, REML = FALSE, useWeights = TRUE, control = vpcontrol, hideErrorsInBackend = FALSE, showWarnings = TRUE, BPPARAM = SerialParam(), ... ) ## S4 method for signature 'matrix' fitExtractVarPartModel( exprObj, formula, data, REML = FALSE, useWeights = TRUE, control = vpcontrol, hideErrorsInBackend = FALSE, showWarnings = TRUE, BPPARAM = SerialParam(), ... ) ## S4 method for signature 'data.frame' fitExtractVarPartModel( exprObj, formula, data, REML = FALSE, useWeights = TRUE, control = vpcontrol, hideErrorsInBackend = FALSE, showWarnings = TRUE, BPPARAM = SerialParam(), ... ) ## S4 method for signature 'EList' fitExtractVarPartModel( exprObj, formula, data, REML = FALSE, useWeights = TRUE, control = vpcontrol, hideErrorsInBackend = FALSE, showWarnings = TRUE, BPPARAM = SerialParam(), ... ) ## S4 method for signature 'ExpressionSet' fitExtractVarPartModel( exprObj, formula, data, REML = FALSE, useWeights = TRUE, control = vpcontrol, hideErrorsInBackend = FALSE, showWarnings = TRUE, BPPARAM = SerialParam(), ... ) ## S4 method for signature 'sparseMatrix' fitExtractVarPartModel( exprObj, formula, data, REML = FALSE, useWeights = TRUE, control = vpcontrol, hideErrorsInBackend = FALSE, showWarnings = TRUE, BPPARAM = SerialParam(), ... )fitExtractVarPartModel( exprObj, formula, data, REML = FALSE, useWeights = TRUE, control = vpcontrol, hideErrorsInBackend = FALSE, showWarnings = TRUE, BPPARAM = SerialParam(), ... ) ## S4 method for signature 'matrix' fitExtractVarPartModel( exprObj, formula, data, REML = FALSE, useWeights = TRUE, control = vpcontrol, hideErrorsInBackend = FALSE, showWarnings = TRUE, BPPARAM = SerialParam(), ... ) ## S4 method for signature 'data.frame' fitExtractVarPartModel( exprObj, formula, data, REML = FALSE, useWeights = TRUE, control = vpcontrol, hideErrorsInBackend = FALSE, showWarnings = TRUE, BPPARAM = SerialParam(), ... ) ## S4 method for signature 'EList' fitExtractVarPartModel( exprObj, formula, data, REML = FALSE, useWeights = TRUE, control = vpcontrol, hideErrorsInBackend = FALSE, showWarnings = TRUE, BPPARAM = SerialParam(), ... ) ## S4 method for signature 'ExpressionSet' fitExtractVarPartModel( exprObj, formula, data, REML = FALSE, useWeights = TRUE, control = vpcontrol, hideErrorsInBackend = FALSE, showWarnings = TRUE, BPPARAM = SerialParam(), ... ) ## S4 method for signature 'sparseMatrix' fitExtractVarPartModel( exprObj, formula, data, REML = FALSE, useWeights = TRUE, control = vpcontrol, hideErrorsInBackend = FALSE, showWarnings = TRUE, BPPARAM = SerialParam(), ... )
exprObj |
matrix of expression data (g genes x n samples), or |
formula |
specifies variables for the linear (mixed) model. Must only specify covariates, since the rows of exprObj are automatically used as a response. e.g.: |
data |
|
REML |
use restricted maximum likelihood to fit linear mixed model. default is FALSE. See Details. |
useWeights |
if TRUE, analysis uses heteroskedastic error estimates from |
control |
control settings for |
hideErrorsInBackend |
default FALSE. If TRUE, hide errors in |
showWarnings |
default TRUE. Indicate model failures |
BPPARAM |
parameters for parallel evaluation |
... |
Additional arguments for |
A linear (mixed) model is fit for each gene in exprObj, using formula to specify variables in the regression. If categorical variables are modeled as random effects (as is recommended), then a linear mixed model us used. For example if formula is ~ a + b + (1|c), then the model is
fit <- lmer( exprObj[j,] ~ a + b + (1|c), data=data)
If there are no random effects, so formula is ~ a + b + c, a 'standard' linear model is used:
fit <- lm( exprObj[j,] ~ a + b + c, data=data)
In both cases, useWeights=TRUE causes weightsMatrix[j,] to be included as weights in the regression model.
Note: Fitting the model for 20,000 genes can be computationally intensive. To accelerate computation, models can be fit in parallel using BiocParallel to run in parallel. Parallel processing must be enabled before calling this function. See below.
The regression model is fit for each gene separately. Samples with missing values in either gene expression or metadata are omitted by the underlying call to lm/lmer.
REML=FALSE uses maximum likelihood to estimate variance fractions. This approach produced unbiased estimates, while REML=TRUE can show substantial bias. See Vignette "3) Theory and practice of random effects and REML"
list() of where each entry is a model fit produced by lmer() or lm()
# load library # library(variancePartition) library(BiocParallel) # load simulated data: # geneExpr: matrix of gene expression values # info: information/metadata about each sample data(varPartData) # Specify variables to consider # Age is continuous so we model it as a fixed effect # Individual and Tissue are both categorical, so we model them as random effects form <- ~ Age + (1 | Individual) + (1 | Tissue) # Step 1: fit linear mixed model on gene expression # If categorical variables are specified, a linear mixed model is used # If all variables are modeled as continuous, a linear model is used # each entry in results is a regression model fit on a single gene # Step 2: extract variance fractions from each model fit # for each gene, returns fraction of variation attributable to each variable # Interpretation: the variance explained by each variable # after correction for all other variables varPart <- fitExtractVarPartModel(geneExpr, form, info) # violin plot of contribution of each variable to total variance plotVarPart(sortCols(varPart)) # Note: fitExtractVarPartModel also accepts ExpressionSet data(sample.ExpressionSet, package = "Biobase") # ExpressionSet example form <- ~ (1 | sex) + (1 | type) + score info2 <- Biobase::pData(sample.ExpressionSet) varPart2 <- fitExtractVarPartModel(sample.ExpressionSet, form, info2)# load library # library(variancePartition) library(BiocParallel) # load simulated data: # geneExpr: matrix of gene expression values # info: information/metadata about each sample data(varPartData) # Specify variables to consider # Age is continuous so we model it as a fixed effect # Individual and Tissue are both categorical, so we model them as random effects form <- ~ Age + (1 | Individual) + (1 | Tissue) # Step 1: fit linear mixed model on gene expression # If categorical variables are specified, a linear mixed model is used # If all variables are modeled as continuous, a linear model is used # each entry in results is a regression model fit on a single gene # Step 2: extract variance fractions from each model fit # for each gene, returns fraction of variation attributable to each variable # Interpretation: the variance explained by each variable # after correction for all other variables varPart <- fitExtractVarPartModel(geneExpr, form, info) # violin plot of contribution of each variable to total variance plotVarPart(sortCols(varPart)) # Note: fitExtractVarPartModel also accepts ExpressionSet data(sample.ExpressionSet, package = "Biobase") # ExpressionSet example form <- ~ (1 | sex) + (1 | type) + score info2 <- Biobase::pData(sample.ExpressionSet) varPart2 <- fitExtractVarPartModel(sample.ExpressionSet, form, info2)
Fit linear (mixed) model to estimate contribution of multiple sources of variation while simultaneously correcting for all other variables.
fitVarPartModel( exprObj, formula, data, REML = FALSE, useWeights = TRUE, fxn = identity, control = vpcontrol, hideErrorsInBackend = FALSE, showWarnings = TRUE, BPPARAM = SerialParam(), ... ) ## S4 method for signature 'matrix' fitVarPartModel( exprObj, formula, data, REML = FALSE, useWeights = TRUE, fxn = identity, control = vpcontrol, hideErrorsInBackend = FALSE, showWarnings = TRUE, BPPARAM = SerialParam(), ... ) ## S4 method for signature 'data.frame' fitVarPartModel( exprObj, formula, data, REML = FALSE, useWeights = TRUE, fxn = identity, control = vpcontrol, hideErrorsInBackend = FALSE, showWarnings = TRUE, BPPARAM = SerialParam(), ... ) ## S4 method for signature 'EList' fitVarPartModel( exprObj, formula, data, REML = FALSE, useWeights = TRUE, fxn = identity, control = vpcontrol, hideErrorsInBackend = FALSE, showWarnings = TRUE, BPPARAM = SerialParam(), ... ) ## S4 method for signature 'ExpressionSet' fitVarPartModel( exprObj, formula, data, REML = FALSE, useWeights = TRUE, fxn = identity, control = vpcontrol, hideErrorsInBackend = FALSE, showWarnings = TRUE, BPPARAM = SerialParam(), ... ) ## S4 method for signature 'sparseMatrix' fitVarPartModel( exprObj, formula, data, REML = FALSE, useWeights = TRUE, fxn = identity, control = vpcontrol, hideErrorsInBackend = FALSE, showWarnings = TRUE, BPPARAM = SerialParam(), ... )fitVarPartModel( exprObj, formula, data, REML = FALSE, useWeights = TRUE, fxn = identity, control = vpcontrol, hideErrorsInBackend = FALSE, showWarnings = TRUE, BPPARAM = SerialParam(), ... ) ## S4 method for signature 'matrix' fitVarPartModel( exprObj, formula, data, REML = FALSE, useWeights = TRUE, fxn = identity, control = vpcontrol, hideErrorsInBackend = FALSE, showWarnings = TRUE, BPPARAM = SerialParam(), ... ) ## S4 method for signature 'data.frame' fitVarPartModel( exprObj, formula, data, REML = FALSE, useWeights = TRUE, fxn = identity, control = vpcontrol, hideErrorsInBackend = FALSE, showWarnings = TRUE, BPPARAM = SerialParam(), ... ) ## S4 method for signature 'EList' fitVarPartModel( exprObj, formula, data, REML = FALSE, useWeights = TRUE, fxn = identity, control = vpcontrol, hideErrorsInBackend = FALSE, showWarnings = TRUE, BPPARAM = SerialParam(), ... ) ## S4 method for signature 'ExpressionSet' fitVarPartModel( exprObj, formula, data, REML = FALSE, useWeights = TRUE, fxn = identity, control = vpcontrol, hideErrorsInBackend = FALSE, showWarnings = TRUE, BPPARAM = SerialParam(), ... ) ## S4 method for signature 'sparseMatrix' fitVarPartModel( exprObj, formula, data, REML = FALSE, useWeights = TRUE, fxn = identity, control = vpcontrol, hideErrorsInBackend = FALSE, showWarnings = TRUE, BPPARAM = SerialParam(), ... )
exprObj |
matrix of expression data (g genes x n samples), or |
formula |
specifies variables for the linear (mixed) model. Must only specify covariates, since the rows of exprObj are automatically used as a response. e.g.: |
data |
|
REML |
use restricted maximum likelihood to fit linear mixed model. default is FALSE. See Details. |
useWeights |
if TRUE, analysis uses heteroskedastic error estimates from voom(). Value is ignored unless exprObj is an |
fxn |
apply function to model fit for each gene. Defaults to identify function so it returns the model fit itself |
control |
control settings for |
hideErrorsInBackend |
default FALSE. If TRUE, hide errors in |
showWarnings |
default TRUE. Indicate model failures |
BPPARAM |
parameters for parallel evaluation |
... |
Additional arguments for |
A linear (mixed) model is fit for each gene in exprObj, using formula to specify variables in the regression. If categorical variables are modeled as random effects (as is recommended), then a linear mixed model us used. For example if formula is ~ a + b + (1|c), then the model is
fit <- lmer( exprObj[j,] ~ a + b + (1|c), data=data)
If there are no random effects, so formula is ~ a + b + c, a 'standard' linear model is used:
fit <- lm( exprObj[j,] ~ a + b + c, data=data)
In both cases, useWeights=TRUE causes weightsMatrix[j,] to be included as weights in the regression model.
Note: Fitting the model for 20,000 genes can be computationally intensive. To accelerate computation, models can be fit in parallel using BiocParallel to run in parallel. Parallel processing must be enabled before calling this function. See below.
The regression model is fit for each gene separately. Samples with missing values in either gene expression or metadata are omitted by the underlying call to lm/lmer.
Since this function returns a list of each model fit, using this function is slower and uses more memory than fitExtractVarPartModel().
REML=FALSE uses maximum likelihood to estimate variance fractions. This approach produced unbiased estimates, while REML=TRUE can show substantial bias. See Vignette "3) Theory and practice of random effects and REML"
list() of where each entry is a model fit produced by lmer() or lm()
# load library # library(variancePartition) library(BiocParallel) # load simulated data: # geneExpr: matrix of gene expression values # info: information/metadata about each sample data(varPartData) # Specify variables to consider # Age is continuous so we model it as a fixed effect # Individual and Tissue are both categorical, so we model them as random effects form <- ~ Age + (1 | Individual) + (1 | Tissue) # Step 1: fit linear mixed model on gene expression # If categorical variables are specified, a linear mixed model is used # If all variables are modeled as continuous, a linear model is used # each entry in results is a regression model fit on a single gene # Step 2: extract variance fractions from each model fit # for each gene, returns fraction of variation attributable to each variable # Interpretation: the variance explained by each variable # after correction for all other variables varPart <- fitExtractVarPartModel(geneExpr, form, info) # violin plot of contribution of each variable to total variance # also sort columns plotVarPart(sortCols(varPart)) # Advanced: # Fit model and extract variance in two separate steps # Step 1: fit model for each gene, store model fit for each gene in a list results <- fitVarPartModel(geneExpr, form, info) # Step 2: extract variance fractions varPart <- extractVarPart(results) # Note: fitVarPartModel also accepts ExpressionSet data(sample.ExpressionSet, package = "Biobase") # ExpressionSet example form <- ~ (1 | sex) + (1 | type) + score info2 <- Biobase::pData(sample.ExpressionSet) results2 <- fitVarPartModel(sample.ExpressionSet, form, info2)# load library # library(variancePartition) library(BiocParallel) # load simulated data: # geneExpr: matrix of gene expression values # info: information/metadata about each sample data(varPartData) # Specify variables to consider # Age is continuous so we model it as a fixed effect # Individual and Tissue are both categorical, so we model them as random effects form <- ~ Age + (1 | Individual) + (1 | Tissue) # Step 1: fit linear mixed model on gene expression # If categorical variables are specified, a linear mixed model is used # If all variables are modeled as continuous, a linear model is used # each entry in results is a regression model fit on a single gene # Step 2: extract variance fractions from each model fit # for each gene, returns fraction of variation attributable to each variable # Interpretation: the variance explained by each variable # after correction for all other variables varPart <- fitExtractVarPartModel(geneExpr, form, info) # violin plot of contribution of each variable to total variance # also sort columns plotVarPart(sortCols(varPart)) # Advanced: # Fit model and extract variance in two separate steps # Step 1: fit model for each gene, store model fit for each gene in a list results <- fitVarPartModel(geneExpr, form, info) # Step 2: extract variance fractions varPart <- extractVarPart(results) # Note: fitVarPartModel also accepts ExpressionSet data(sample.ExpressionSet, package = "Biobase") # ExpressionSet example form <- ~ (1 | sex) + (1 | type) + score info2 <- Biobase::pData(sample.ExpressionSet) results2 <- fitVarPartModel(sample.ExpressionSet, form, info2)
Compute predicted value of formula for linear (mixed) model for with lm or lmer
get_prediction(fit, formula) ## S4 method for signature 'lmerMod' get_prediction(fit, formula) ## S4 method for signature 'lm' get_prediction(fit, formula)get_prediction(fit, formula) ## S4 method for signature 'lmerMod' get_prediction(fit, formula) ## S4 method for signature 'lm' get_prediction(fit, formula)
fit |
model fit with |
formula |
formula of fixed and random effects to predict |
Similar motivation as lme4:::predict.merMod(), but that function cannot use just a subset of the fixed effects: it either uses none or all. Note that the intercept is included in the formula by default. To exclude it from the prediction use ~ 0 + ... syntax
Predicted values from formula using parameter estimates from fit linear (mixed) model
library(lme4) # Linear model fit <- lm(Reaction ~ Days, sleepstudy) # prediction of intercept get_prediction(fit, ~1) # prediction of Days without intercept get_prediction(fit, ~ 0 + Days) # Linear mixed model # fit model fm1 <- lmer(Reaction ~ Days + (Days | Subject), sleepstudy) # predict Days, but exclude intercept get_prediction(fm1, ~ 0 + Days) # predict Days and (Days | Subject) random effect, but exclude intercept get_prediction(fm1, ~ 0 + Days + (Days | Subject))library(lme4) # Linear model fit <- lm(Reaction ~ Days, sleepstudy) # prediction of intercept get_prediction(fit, ~1) # prediction of Days without intercept get_prediction(fit, ~ 0 + Days) # Linear mixed model # fit model fm1 <- lmer(Reaction ~ Days + (Days | Subject), sleepstudy) # predict Days, but exclude intercept get_prediction(fm1, ~ 0 + Days) # predict Days and (Days | Subject) random effect, but exclude intercept get_prediction(fm1, ~ 0 + Days + (Days | Subject))
Extract contrast matrix, L, testing a single variable. Contrasts involving more than one variable can be constructed by modifying L directly
getContrast(exprObj, formula, data, coefficient)getContrast(exprObj, formula, data, coefficient)
exprObj |
matrix of expression data (g genes x n samples), or |
formula |
specifies variables for the linear (mixed) model. Must only specify covariates, since the rows of exprObj are automatically used as a response. e.g.: |
data |
data.frame with columns corresponding to formula |
coefficient |
the coefficient to use in the hypothesis test |
Contrast matrix testing one variable
# load simulated data: # geneExpr: matrix of gene expression values # info: information/metadata about each sample data(varPartData) # get contrast matrix testing if the coefficient for Batch2 is zero # The variable of interest must be a fixed effect form <- ~ Batch + (1 | Individual) + (1 | Tissue) L <- getContrast(geneExpr, form, info, "Batch3") # get contrast matrix testing if Batch3 - Batch2 = 0 form <- ~ Batch + (1 | Individual) + (1 | Tissue) L <- getContrast(geneExpr, form, info, c("Batch3", "Batch2")) # To test against Batch1 use the formula: # ~ 0 + Batch + (1|Individual) + (1|Tissue) # to estimate Batch1 directly instead of using it as the baseline# load simulated data: # geneExpr: matrix of gene expression values # info: information/metadata about each sample data(varPartData) # get contrast matrix testing if the coefficient for Batch2 is zero # The variable of interest must be a fixed effect form <- ~ Batch + (1 | Individual) + (1 | Tissue) L <- getContrast(geneExpr, form, info, "Batch3") # get contrast matrix testing if Batch3 - Batch2 = 0 form <- ~ Batch + (1 | Individual) + (1 | Tissue) L <- getContrast(geneExpr, form, info, c("Batch3", "Batch2")) # To test against Batch1 use the formula: # ~ 0 + Batch + (1|Individual) + (1|Tissue) # to estimate Batch1 directly instead of using it as the baseline
Test if coefficient is different from a specified value
getTreat(fit, lfc = log2(1.2), coef = 1, number = 10, sort.by = "p") ## S4 method for signature 'MArrayLM' getTreat(fit, lfc = log2(1.2), coef = 1, number = 10, sort.by = "p") ## S4 method for signature 'MArrayLM2' getTreat(fit, lfc = log2(1.2), coef = 1, number = 10, sort.by = "p")getTreat(fit, lfc = log2(1.2), coef = 1, number = 10, sort.by = "p") ## S4 method for signature 'MArrayLM' getTreat(fit, lfc = log2(1.2), coef = 1, number = 10, sort.by = "p") ## S4 method for signature 'MArrayLM2' getTreat(fit, lfc = log2(1.2), coef = 1, number = 10, sort.by = "p")
fit |
fit |
lfc |
a minimum log2-fold-change below which changes not considered scientifically meaningful |
coef |
which coefficient to test |
number |
number of genes to return |
sort.by |
column to sort by |
results of getTreat
data(varPartData) form <- ~ Age + Batch + (1 | Individual) + (1 | Tissue) fit <- dream(geneExpr, form, info) fit <- eBayes(fit) coef <- "Age" # Evaluate treat()/topTreat() in a way that works seamlessly for dream() getTreat(fit, lfc = log2(1.03), coef, sort.by = "none", number = 3)data(varPartData) form <- ~ Age + Batch + (1 | Individual) + (1 | Tissue) fit <- dream(geneExpr, form, info) fit <- eBayes(fit) coef <- "Age" # Evaluate treat()/topTreat() in a way that works seamlessly for dream() getTreat(fit, lfc = log2(1.03), coef, sort.by = "none", number = 3)
Return an array of n colors the same as the default used by ggplot2
ggColorHue(n)ggColorHue(n)
n |
number of colors |
array of colors of length n
ggColorHue(4)ggColorHue(4)
Compute hatvalues from dream fit
## S4 method for signature 'MArrayLM' hatvalues(model, vobj, ...) ## S4 method for signature 'MArrayLM2' hatvalues(model, ...)## S4 method for signature 'MArrayLM' hatvalues(model, vobj, ...) ## S4 method for signature 'MArrayLM2' hatvalues(model, ...)
model |
model fit from |
vobj |
|
... |
other arguments, currently ignored |
Test if formula is full rank on this dataset
isRunableFormula(exprObj, formula, data)isRunableFormula(exprObj, formula, data)
exprObj |
expression object |
formula |
formula |
data |
data |
Log-likelihood from model fit
## S3 method for class 'MArrayLM' logLik(object, vobj, ...)## S3 method for class 'MArrayLM' logLik(object, vobj, ...)
object |
result of |
vobj |
|
... |
See |
Log-likelihood from model fit
## S3 method for class 'MArrayLM2' logLik(object, ...)## S3 method for class 'MArrayLM2' logLik(object, ...)
object |
result of |
... |
See |
Construct the contrast matrix corresponding to specified contrasts of a set of parameters. Each specified set of contrast weights must sum to 1.
makeContrastsDream( formula, data, ..., contrasts = NULL, suppressWarnings = FALSE, nullOnError = FALSE )makeContrastsDream( formula, data, ..., contrasts = NULL, suppressWarnings = FALSE, nullOnError = FALSE )
formula |
specifies variables for the linear (mixed) model. Must only specify covariates, since the rows of exprObj are automatically used as a response. e.g.: |
data |
data.frame with columns corresponding to formula |
... |
expressions, or character strings which can be parsed to expressions, specifying contrasts |
contrasts |
character vector specifying contrasts |
suppressWarnings |
(default FALSE). suppress warnings for univariate contrasts |
nullOnError |
(default FALSE). When a contrast entry is invalid, throw warning and return NULL for that contrast entry |
This function expresses contrasts between a set of parameters as a numeric matrix. The parameters are usually the coefficients from a linear (mixed) model fit, so the matrix specifies which comparisons between the coefficients are to be extracted from the fit. The output from this function is usually used as input to dream().
This function creates a matrix storing the contrasts weights that are applied to each coefficient.
Consider a variable v with levels c('A', 'B', 'C'). A contrast comparing A and B is 'vA - vB' and tests whether the difference between these levels is different than zero. Coded for the 3 levels this has weights c(1, -1, 0). In order to compare A to the other levels, the contrast is 'vA - (vB + vC)/2' so that A is compared to the average of the other two levels. This is encoded as c(1, -0.5, -0.5). This type of proper matching in testing multiple levels is enforced by ensuring that the contrast weights sum to 1. Based on standard regression theory only weighted sums of the estimated coefficients are supported.
This function is inspired by limma::makeContrasts() but is designed to be compatible with linear mixed models for dream()
Names in ... and contrasts will be used as column names in the returned value.
matrix of linear contrasts between regression coefficients
plotContrasts()
# load library # library(variancePartition) library(BiocParallel) # load simulated data: # geneExpr: matrix of gene expression values # info: information/metadata about each sample data(varPartData) form <- ~ 0 + Batch + (1 | Individual) + (1 | Tissue) # Define contrasts # Note that for each contrass, the weights sum to 1 L <- makeContrastsDream(form, info, contrasts = c(Batch1_vs_2 = "Batch1 - Batch2", Batch3_vs_4 = "Batch3 - Batch4", Batch1_vs_34 = "Batch1 - (Batch3 + Batch4)/2")) # show contrasts matrix L # Plot to visualize contrasts matrix plotContrasts(L) # Fit linear mixed model for each gene # run on just 10 genes for time fit <- dream(geneExpr[1:10, ], form, info, L = L) # examine contrasts after fitting head(coef(fit)) # show results from first contrast topTable(fit, coef = "Batch1_vs_2") # show results from second contrast topTable(fit, coef = "Batch3_vs_4") # show results from third contrast topTable(fit, coef = "Batch1_vs_34")# load library # library(variancePartition) library(BiocParallel) # load simulated data: # geneExpr: matrix of gene expression values # info: information/metadata about each sample data(varPartData) form <- ~ 0 + Batch + (1 | Individual) + (1 | Tissue) # Define contrasts # Note that for each contrass, the weights sum to 1 L <- makeContrastsDream(form, info, contrasts = c(Batch1_vs_2 = "Batch1 - Batch2", Batch3_vs_4 = "Batch3 - Batch4", Batch1_vs_34 = "Batch1 - (Batch3 + Batch4)/2")) # show contrasts matrix L # Plot to visualize contrasts matrix plotContrasts(L) # Fit linear mixed model for each gene # run on just 10 genes for time fit <- dream(geneExpr[1:10, ], form, info, L = L) # examine contrasts after fitting head(coef(fit)) # show results from first contrast topTable(fit, coef = "Batch1_vs_2") # show results from second contrast topTable(fit, coef = "Batch3_vs_4") # show results from third contrast topTable(fit, coef = "Batch1_vs_34")
dream()
Evaluate multivariate tests on results from dream() using vcov() to compute the covariance between estimated regression coefficients across multiple responses. A joint test to see if the coefficients are jointly different from zero is performed using meta-analysis methods that account for the covariance.
mvTest( fit, vobj, features, coef, method = c("FE.empirical", "FE", "RE2C", "tstat", "hotelling", "sidak", "fisher"), shrink.cov = TRUE, BPPARAM = SerialParam(), ... ) ## S4 method for signature 'MArrayLM,EList,vector' mvTest( fit, vobj, features, coef, method = c("FE.empirical", "FE", "RE2C", "tstat", "hotelling", "sidak", "fisher"), shrink.cov = TRUE, BPPARAM = SerialParam(), ... ) ## S4 method for signature 'MArrayLM,EList,missing' mvTest( fit, vobj, features, coef, method = c("FE.empirical", "FE", "RE2C", "tstat", "hotelling", "sidak", "fisher"), shrink.cov = TRUE, BPPARAM = SerialParam(), ... ) ## S4 method for signature 'MArrayLM,EList,list' mvTest( fit, vobj, features, coef, method = c("FE.empirical", "FE", "RE2C", "tstat", "hotelling", "sidak", "fisher"), shrink.cov = TRUE, BPPARAM = SerialParam(), ... ) ## S4 method for signature 'mvTest_input,ANY,ANY' mvTest( fit, vobj, features, coef, method = c("FE.empirical", "FE", "RE2C", "tstat", "hotelling", "sidak", "fisher"), shrink.cov = TRUE, BPPARAM = SerialParam(), ... ) ## S4 method for signature 'MArrayLM,matrix,ANY' mvTest( fit, vobj, features, coef, method = c("FE.empirical", "FE", "RE2C", "tstat", "hotelling", "sidak", "fisher"), shrink.cov = TRUE, BPPARAM = SerialParam(), ... )mvTest( fit, vobj, features, coef, method = c("FE.empirical", "FE", "RE2C", "tstat", "hotelling", "sidak", "fisher"), shrink.cov = TRUE, BPPARAM = SerialParam(), ... ) ## S4 method for signature 'MArrayLM,EList,vector' mvTest( fit, vobj, features, coef, method = c("FE.empirical", "FE", "RE2C", "tstat", "hotelling", "sidak", "fisher"), shrink.cov = TRUE, BPPARAM = SerialParam(), ... ) ## S4 method for signature 'MArrayLM,EList,missing' mvTest( fit, vobj, features, coef, method = c("FE.empirical", "FE", "RE2C", "tstat", "hotelling", "sidak", "fisher"), shrink.cov = TRUE, BPPARAM = SerialParam(), ... ) ## S4 method for signature 'MArrayLM,EList,list' mvTest( fit, vobj, features, coef, method = c("FE.empirical", "FE", "RE2C", "tstat", "hotelling", "sidak", "fisher"), shrink.cov = TRUE, BPPARAM = SerialParam(), ... ) ## S4 method for signature 'mvTest_input,ANY,ANY' mvTest( fit, vobj, features, coef, method = c("FE.empirical", "FE", "RE2C", "tstat", "hotelling", "sidak", "fisher"), shrink.cov = TRUE, BPPARAM = SerialParam(), ... ) ## S4 method for signature 'MArrayLM,matrix,ANY' mvTest( fit, vobj, features, coef, method = c("FE.empirical", "FE", "RE2C", "tstat", "hotelling", "sidak", "fisher"), shrink.cov = TRUE, BPPARAM = SerialParam(), ... )
fit |
|
vobj |
matrix or |
features |
a) indeces or names of features to perform multivariate test on, b) list of indeces or names. If missing, perform joint test on all features. |
coef |
name of coefficient or contrast to be tested |
method |
statistical method used to perform multivariate test. See details. |
shrink.cov |
shrink the covariance matrix between coefficients using the Schafer-Strimmer method |
BPPARAM |
parameters for parallel evaluation |
... |
other arugments |
See package remaCor for details about the remaCor::RE2C() test, and see remaCor::LS() for details about the fixed effect test. When only 1 feature is selected, the original p-value is returned and the test statistic is set to NA.
For the "RE2C" test, the final test statistic is the sum of a test statistic for the mean effect (stat.FE) and heterogeneity across effects (stat.het). mvTest() returns 0 if stat.het is negative in extremely rare cases.
Returns a data.frame with the statistics from each test, the pvalue from the test, n_features, method, and lambda from the Schafer-Strimmer method to shrink the estimated covariance. When shrink.cov=FALSE, lambda = 0.
# library(variancePartition) library(edgeR) library(BiocParallel) data(varPartDEdata) # normalize RNA-seq counts dge <- DGEList(counts = countMatrix) dge <- calcNormFactors(dge) # specify formula with random effect for Individual form <- ~ Disease + (1 | Individual) # compute observation weights vobj <- voomWithDreamWeights(dge[1:20, ], form, metadata) # fit dream model fit <- dream(vobj, form, metadata) fit <- eBayes(fit) # Multivariate test of features 1 and 2 mvTest(fit, vobj, 1:2, coef = "Disease1") # Test multiple sets of features lst <- list(a = 1:2, b = 3:4) mvTest(fit, vobj, lst, coef = "Disease1", BPPARAM = SnowParam(2))# library(variancePartition) library(edgeR) library(BiocParallel) data(varPartDEdata) # normalize RNA-seq counts dge <- DGEList(counts = countMatrix) dge <- calcNormFactors(dge) # specify formula with random effect for Individual form <- ~ Disease + (1 | Individual) # compute observation weights vobj <- voomWithDreamWeights(dge[1:20, ], form, metadata) # fit dream model fit <- dream(vobj, form, metadata) fit <- eBayes(fit) # Multivariate test of features 1 and 2 mvTest(fit, vobj, 1:2, coef = "Disease1") # Test multiple sets of features lst <- list(a = 1:2, b = 3:4) mvTest(fit, vobj, lst, coef = "Disease1", BPPARAM = SnowParam(2))
Plot -log10 p-values from two analyses and color based on donor component from variancePartition analysis
plotCompareP( p1, p2, vpDonor, dupcorvalue, fraction = 0.2, xlabel = bquote(duplicateCorrelation ~ (-log[10] ~ p)), ylabel = bquote(dream ~ (-log[10] ~ p)) )plotCompareP( p1, p2, vpDonor, dupcorvalue, fraction = 0.2, xlabel = bquote(duplicateCorrelation ~ (-log[10] ~ p)), ylabel = bquote(dream ~ (-log[10] ~ p)) )
p1 |
p-value from first analysis |
p2 |
p-value from second analysis |
vpDonor |
donor component for each gene from variancePartition analysis |
dupcorvalue |
scalar donor component from duplicateCorrelation |
fraction |
fraction of highest/lowest values to use for best fit lines |
xlabel |
for x-axis |
ylabel |
label for y-axis |
ggplot2 plot
# load library # library(variancePartition) library(BiocParallel) # load simulated data: # geneExpr: matrix of gene expression values # info: information/metadata about each sample data(varPartData) # Perform very simple analysis for demonstration # Analysis 1 form <- ~Batch fit <- dream(geneExpr, form, info) fit <- eBayes(fit) res <- topTable(fit, number = Inf, coef = "Batch3") # Analysis 2 form <- ~ Batch + (1 | Tissue) fit2 <- dream(geneExpr, form, info) res2 <- topTable(fit2, number = Inf, coef = "Batch3") # Compare p-values plotCompareP(res$P.Value, res2$P.Value, runif(nrow(res)), .3)# load library # library(variancePartition) library(BiocParallel) # load simulated data: # geneExpr: matrix of gene expression values # info: information/metadata about each sample data(varPartData) # Perform very simple analysis for demonstration # Analysis 1 form <- ~Batch fit <- dream(geneExpr, form, info) fit <- eBayes(fit) res <- topTable(fit, number = Inf, coef = "Batch3") # Analysis 2 form <- ~ Batch + (1 | Tissue) fit2 <- dream(geneExpr, form, info) res2 <- topTable(fit2, number = Inf, coef = "Batch3") # Compare p-values plotCompareP(res$P.Value, res2$P.Value, runif(nrow(res)), .3)
Plot contrast matrix to clarify interpretation of hypothesis tests with linear contrasts
plotContrasts(L)plotContrasts(L)
L |
contrast matrix |
This plot shows the contrasts weights that are applied to each coefficient.
Consider a variable v with levels c('A', 'B', 'C'). A contrast comparing A and B is 'vA - vB' and tests whether the difference between these levels is different than zero. Coded for the 3 levels this has weights c(1, -1, 0). In order to compare A to the other levels, the contrast is 'vA - (vB + vC)/2' so that A is compared to the average of the other two levels. This is encoded as c(1, -0.5, -0.5). This type of proper matching in testing multiple levels is enforced by ensuring that the contrast weights sum to 1. Based on standard regression theory only weighted sums of the estimated coefficients are supported.
ggplot2 object
makeContrastsDream()
# load library # library(variancePartition) # load simulated data: # geneExpr: matrix of gene expression values # info: information/metadata about each sample data(varPartData) # 1) get contrast matrix testing if the coefficient for Batch2 is different from Batch3 form <- ~ Batch + (1 | Individual) + (1 | Tissue) L <- makeContrastsDream(form, info, contrasts = c(Batch_3_vs_2 = "Batch3 - Batch2")) # plot contrasts plotContrasts(L)# load library # library(variancePartition) # load simulated data: # geneExpr: matrix of gene expression values # info: information/metadata about each sample data(varPartData) # 1) get contrast matrix testing if the coefficient for Batch2 is different from Batch3 form <- ~ Batch + (1 | Individual) + (1 | Tissue) L <- makeContrastsDream(form, info, contrasts = c(Batch_3_vs_2 = "Batch3 - Batch2")) # plot contrasts plotContrasts(L)
Plot correlation matrix
plotCorrMatrix( C, dendrogram = "both", sort = TRUE, margins = c(13, 13), key.xlab = "correlation", ... )plotCorrMatrix( C, dendrogram = "both", sort = TRUE, margins = c(13, 13), key.xlab = "correlation", ... )
C |
correlation matrix: R or R^2 matrix |
dendrogram |
character string indicating whether to draw 'both' or none' |
sort |
sort rows and columns based on clustering |
margins |
spacing of plot |
key.xlab |
label of color gradient |
... |
additional arguments to heatmap.2 |
Plots image of correlation matrix using customized call to heatmap.2
Image of correlation matrix
# simulate simple matrix of 10 variables mat <- matrix(rnorm(1000), ncol = 10) # compute correlation matrix C <- cor(mat) # plot correlations plotCorrMatrix(C) # plot squared correlations plotCorrMatrix(C^2, dendrogram = "none")# simulate simple matrix of 10 variables mat <- matrix(rnorm(1000), ncol = 10) # compute correlation matrix C <- cor(mat) # plot correlations plotCorrMatrix(C) # plot squared correlations plotCorrMatrix(C^2, dendrogram = "none")
Plot correlation structure of a gene based on random effects
plotCorrStructure( fit, varNames = names(coef(fit)), reorder = TRUE, pal = colorRampPalette(c("white", "red", "darkred")), hclust.method = "complete" )plotCorrStructure( fit, varNames = names(coef(fit)), reorder = TRUE, pal = colorRampPalette(c("white", "red", "darkred")), hclust.method = "complete" )
fit |
linear mixed model fit of a gene produced by lmer() or fitVarPartModel() |
varNames |
variables in the metadata for which the correlation structure should be shown. Variables must be random effects |
reorder |
how to reorder the rows/columns of the correlation matrix. reorder=FALSE gives no reorder. reorder=TRUE reorders based on hclust. reorder can also be an array of indices to reorder the samples manually |
pal |
color palette |
hclust.method |
clustering methods for hclust |
Image of correlation structure between each pair of experiments for a single gene
# load library # library(variancePartition) library(BiocParallel) # load simulated data: data(varPartData) # specify formula form <- ~ Age + (1 | Individual) + (1 | Tissue) # fit and return linear mixed models for each gene fitList <- fitVarPartModel(geneExpr[1:10, ], form, info) # Focus on the first gene fit <- fitList[[1]] # plot correlation sturcture based on Individual, reordering samples with hclust plotCorrStructure(fit, "Individual") # don't reorder plotCorrStructure(fit, "Individual", reorder = FALSE) # plot correlation sturcture based on Tissue, reordering samples with hclust plotCorrStructure(fit, "Tissue") # don't reorder plotCorrStructure(fit, "Tissue", FALSE) # plot correlation structure based on all random effects # reorder manually by Tissue and Individual idx <- order(info$Tissue, info$Individual) plotCorrStructure(fit, reorder = idx) # plot correlation structure based on all random effects # reorder manually by Individual, then Tissue idx <- order(info$Individual, info$Tissue) plotCorrStructure(fit, reorder = idx)# load library # library(variancePartition) library(BiocParallel) # load simulated data: data(varPartData) # specify formula form <- ~ Age + (1 | Individual) + (1 | Tissue) # fit and return linear mixed models for each gene fitList <- fitVarPartModel(geneExpr[1:10, ], form, info) # Focus on the first gene fit <- fitList[[1]] # plot correlation sturcture based on Individual, reordering samples with hclust plotCorrStructure(fit, "Individual") # don't reorder plotCorrStructure(fit, "Individual", reorder = FALSE) # plot correlation sturcture based on Tissue, reordering samples with hclust plotCorrStructure(fit, "Tissue") # don't reorder plotCorrStructure(fit, "Tissue", FALSE) # plot correlation structure based on all random effects # reorder manually by Tissue and Individual idx <- order(info$Tissue, info$Individual) plotCorrStructure(fit, reorder = idx) # plot correlation structure based on all random effects # reorder manually by Individual, then Tissue idx <- order(info$Individual, info$Tissue) plotCorrStructure(fit, reorder = idx)
Bar plot of fractions for a subset of genes
plotPercentBars( x, col = c(ggColorHue(ncol(x) - 1), "grey85"), genes = rownames(x), width = NULL, ... ) ## S4 method for signature 'matrix' plotPercentBars( x, col = c(ggColorHue(ncol(x) - 1), "grey85"), genes = rownames(x), width = NULL, ... ) ## S4 method for signature 'data.frame' plotPercentBars( x, col = c(ggColorHue(ncol(x) - 1), "grey85"), genes = rownames(x), width = NULL, ... ) ## S4 method for signature 'varPartResults' plotPercentBars( x, col = c(ggColorHue(ncol(x) - 1), "grey85"), genes = rownames(x), width = NULL, ... )plotPercentBars( x, col = c(ggColorHue(ncol(x) - 1), "grey85"), genes = rownames(x), width = NULL, ... ) ## S4 method for signature 'matrix' plotPercentBars( x, col = c(ggColorHue(ncol(x) - 1), "grey85"), genes = rownames(x), width = NULL, ... ) ## S4 method for signature 'data.frame' plotPercentBars( x, col = c(ggColorHue(ncol(x) - 1), "grey85"), genes = rownames(x), width = NULL, ... ) ## S4 method for signature 'varPartResults' plotPercentBars( x, col = c(ggColorHue(ncol(x) - 1), "grey85"), genes = rownames(x), width = NULL, ... )
x |
object storing fractions |
col |
color of bars for each variable |
genes |
name of genes to plot |
width |
specify width of bars |
... |
other arguments |
Returns ggplot2 barplot
# library(variancePartition) library(BiocParallel) # load simulated data: # geneExpr: matrix of gene expression values # info: information/metadata about each sample data(varPartData) # Specify variables to consider form <- ~ Age + (1 | Individual) + (1 | Tissue) # Fit model varPart <- fitExtractVarPartModel(geneExpr, form, info) # Bar plot for a subset of genes showing variance fractions plotPercentBars(varPart[1:5, ]) # Move the legend to the top plotPercentBars(varPart[1:5, ]) + theme(legend.position = "top")# library(variancePartition) library(BiocParallel) # load simulated data: # geneExpr: matrix of gene expression values # info: information/metadata about each sample data(varPartData) # Specify variables to consider form <- ~ Age + (1 | Individual) + (1 | Tissue) # Fit model varPart <- fitExtractVarPartModel(geneExpr, form, info) # Bar plot for a subset of genes showing variance fractions plotPercentBars(varPart[1:5, ]) # Move the legend to the top plotPercentBars(varPart[1:5, ]) + theme(legend.position = "top")
Plot gene expression stratified by another variable
plotStratify( formula, data, xlab, ylab, main, sortBy, colorBy, sort = TRUE, text = NULL, text.y = 1, text.size = 5, pts.cex = 1, ylim = NULL, legend = TRUE, x.labels = FALSE )plotStratify( formula, data, xlab, ylab, main, sortBy, colorBy, sort = TRUE, text = NULL, text.y = 1, text.size = 5, pts.cex = 1, ylim = NULL, legend = TRUE, x.labels = FALSE )
formula |
specify variables shown in the x- and y-axes. Y-axis should be continuous variable, x-axis should be discrete. |
data |
data.frame storing continuous and discrete variables specified in formula |
xlab |
label x-asis. Defaults to value of xval |
ylab |
label y-asis. Defaults to value of yval |
main |
main label |
sortBy |
name of column in geneExpr to sort samples by. Defaults to xval |
colorBy |
name of column in geneExpr to color box plots. Defaults to xval |
sort |
if TRUE, sort boxplots by median value, else use default ordering |
text |
plot text on the top left of the plot |
text.y |
indicate position of the text on the y-axis as a fraction of the y-axis range |
text.size |
size of text |
pts.cex |
size of points |
ylim |
specify range of y-axis |
legend |
show legend |
x.labels |
show x axis labels |
ggplot2 object
# Note: This is a newer, more convient interface to plotStratifyBy() # load library # library(variancePartition) # load simulated data: data(varPartData) # Create data.frame with expression and Tissue information for each sample GE <- data.frame(Expression = geneExpr[1, ], Tissue = info$Tissue) # Plot expression stratified by Tissue plotStratify(Expression ~ Tissue, GE) # Omit legend and color boxes grey plotStratify(Expression ~ Tissue, GE, colorBy = NULL) # Specify colors col <- c(B = "green", A = "red", C = "yellow") plotStratify(Expression ~ Tissue, GE, colorBy = col, sort = FALSE)# Note: This is a newer, more convient interface to plotStratifyBy() # load library # library(variancePartition) # load simulated data: data(varPartData) # Create data.frame with expression and Tissue information for each sample GE <- data.frame(Expression = geneExpr[1, ], Tissue = info$Tissue) # Plot expression stratified by Tissue plotStratify(Expression ~ Tissue, GE) # Omit legend and color boxes grey plotStratify(Expression ~ Tissue, GE, colorBy = NULL) # Specify colors col <- c(B = "green", A = "red", C = "yellow") plotStratify(Expression ~ Tissue, GE, colorBy = col, sort = FALSE)
Plot gene expression stratified by another variable
plotStratifyBy( geneExpr, xval, yval, xlab = xval, ylab = yval, main = NULL, sortBy = xval, colorBy = xval, sort = TRUE, text = NULL, text.y = 1, text.size = 5, pts.cex = 1, ylim = NULL, legend = TRUE, x.labels = FALSE )plotStratifyBy( geneExpr, xval, yval, xlab = xval, ylab = yval, main = NULL, sortBy = xval, colorBy = xval, sort = TRUE, text = NULL, text.y = 1, text.size = 5, pts.cex = 1, ylim = NULL, legend = TRUE, x.labels = FALSE )
geneExpr |
data.frame of gene expression values and another variable for each sample. If there are multiple columns, the user can specify which one to use |
xval |
name of column in geneExpr to be used along x-axis to stratify gene expression |
yval |
name of column in geneExpr indicating gene expression |
xlab |
label x-asis. Defaults to value of xval |
ylab |
label y-asis. Defaults to value of yval |
main |
main label |
sortBy |
name of column in geneExpr to sort samples by. Defaults to xval |
colorBy |
name of column in geneExpr to color box plots. Defaults to xval |
sort |
if TRUE, sort boxplots by median value, else use default ordering |
text |
plot text on the top left of the plot |
text.y |
indicate position of the text on the y-axis as a fraction of the y-axis range |
text.size |
size of text |
pts.cex |
size of points |
ylim |
specify range of y-axis |
legend |
show legend |
x.labels |
show x axis labels |
ggplot2 object
# load library # library(variancePartition) # load simulated data: data(varPartData) # Create data.frame with expression and Tissue information for each sample GE <- data.frame(Expression = geneExpr[1, ], Tissue = info$Tissue) # Plot expression stratified by Tissue plotStratifyBy(GE, "Tissue", "Expression") # Omit legend and color boxes grey plotStratifyBy(GE, "Tissue", "Expression", colorBy = NULL) # Specify colors col <- c(B = "green", A = "red", C = "yellow") plotStratifyBy(GE, "Tissue", "Expression", colorBy = col, sort = FALSE)# load library # library(variancePartition) # load simulated data: data(varPartData) # Create data.frame with expression and Tissue information for each sample GE <- data.frame(Expression = geneExpr[1, ], Tissue = info$Tissue) # Plot expression stratified by Tissue plotStratifyBy(GE, "Tissue", "Expression") # Omit legend and color boxes grey plotStratifyBy(GE, "Tissue", "Expression", colorBy = NULL) # Specify colors col <- c(B = "green", A = "red", C = "yellow") plotStratifyBy(GE, "Tissue", "Expression", colorBy = col, sort = FALSE)
Plot Variance Estimates
plotVarianceEstimates( fit, fitEB, var_true = NULL, xmax = quantile(fit$sigma^2, 0.999) )plotVarianceEstimates( fit, fitEB, var_true = NULL, xmax = quantile(fit$sigma^2, 0.999) )
fit |
model fit from |
fitEB |
model fit from |
var_true |
array of true variance values from simulation (optional) |
xmax |
maximum value on the x-axis |
Violin plot of variance fraction for each gene and each variable
plotVarPart( obj, col = c(ggColorHue(ncol(obj) - 1), "grey85"), label.angle = 20, main = "", ylab = "", convertToPercent = TRUE, ... ) ## S4 method for signature 'matrix' plotVarPart( obj, col = c(ggColorHue(ncol(obj) - 1), "grey85"), label.angle = 20, main = "", ylab = "", convertToPercent = TRUE, ... ) ## S4 method for signature 'data.frame' plotVarPart( obj, col = c(ggColorHue(ncol(obj) - 1), "grey85"), label.angle = 20, main = "", ylab = "", convertToPercent = TRUE, ... ) ## S4 method for signature 'varPartResults' plotVarPart( obj, col = c(ggColorHue(ncol(obj) - 1), "grey85"), label.angle = 20, main = "", ylab = "", convertToPercent = TRUE, ... )plotVarPart( obj, col = c(ggColorHue(ncol(obj) - 1), "grey85"), label.angle = 20, main = "", ylab = "", convertToPercent = TRUE, ... ) ## S4 method for signature 'matrix' plotVarPart( obj, col = c(ggColorHue(ncol(obj) - 1), "grey85"), label.angle = 20, main = "", ylab = "", convertToPercent = TRUE, ... ) ## S4 method for signature 'data.frame' plotVarPart( obj, col = c(ggColorHue(ncol(obj) - 1), "grey85"), label.angle = 20, main = "", ylab = "", convertToPercent = TRUE, ... ) ## S4 method for signature 'varPartResults' plotVarPart( obj, col = c(ggColorHue(ncol(obj) - 1), "grey85"), label.angle = 20, main = "", ylab = "", convertToPercent = TRUE, ... )
obj |
|
col |
vector of colors |
label.angle |
angle of labels on x-axis |
main |
title of plot |
ylab |
text on y-axis |
convertToPercent |
multiply fractions by 100 to convert to percent values |
... |
additional arguments |
Makes violin plots of variance components model. This function uses the graphics interface from ggplot2. Warnings produced by this function usually ggplot2 warning that the window is too small.
# load library # library(variancePartition) library(BiocParallel) # load simulated data: # geneExpr: matrix of gene expression values # info: information/metadata about each sample data(varPartData) # Specify variables to consider # Age is continuous so we model it as a fixed effect # Individual and Tissue are both categorical, so we model them as random effects form <- ~ Age + (1 | Individual) + (1 | Tissue) varPart <- fitExtractVarPartModel(geneExpr, form, info) # violin plot of contribution of each variable to total variance plotVarPart(sortCols(varPart))# load library # library(variancePartition) library(BiocParallel) # load simulated data: # geneExpr: matrix of gene expression values # info: information/metadata about each sample data(varPartData) # Specify variables to consider # Age is continuous so we model it as a fixed effect # Individual and Tissue are both categorical, so we model them as random effects form <- ~ Age + (1 | Individual) + (1 | Tissue) varPart <- fitExtractVarPartModel(geneExpr, form, info) # violin plot of contribution of each variable to total variance plotVarPart(sortCols(varPart))
Residual degrees of freedom
rdf(fit)rdf(fit)
fit |
model fit from |
rdf.merMod
library(lme4) fit <- lm(Reaction ~ Days, sleepstudy) rdf(fit)library(lme4) fit <- lm(Reaction ~ Days, sleepstudy) rdf(fit)
Defining where and are low rank, compute
in instead of .
rdf_from_matrices(A, B)rdf_from_matrices(A, B)
A |
a |
B |
a |
rdf.merMod
For a linear model with samples and covariates, where is the residual degrees of freedom. In the case of a linear mixed model, the distribution is no longer exactly a chi-square distribution, but can be approximated with a chi-square distribution.
Given the hat matrix, , that maps between observed and fitted responses, the approximate residual degrees of freedom is . For a linear model, this simplifies to the well known form . In the more general case, such as a linear mixed model, the original form simplifies only to and is an approximation rather than being exact. The third term here is quadratic time in the number of samples, , and can be computationally expensive to evaluate for larger datasets. Here we develop a linear time algorithm that takes advantage of the fact that is low rank.
is computed as for A=CL and B=CR defined in the code. Since and are low rank, there is no need to compute directly. Instead, the terms and can be computed using the eigen decompositions of and which is linear time in the number of samples.
rdf.merMod(model, method = c("linear", "quadratic"))rdf.merMod(model, method = c("linear", "quadratic"))
model |
An object of class |
method |
Use algorithm that is "linear" (default) or quadratic time in the number of samples |
Compute the approximate residual degrees of freedom from a linear mixed model.
residual degrees of freedom
rdf_from_matrices
library(lme4) # Fit linear mixed model fit <- lmer(Reaction ~ Days + (Days | Subject), sleepstudy) # Evaluate the approximate residual degrees of freedom rdf.merMod(fit)library(lme4) # Fit linear mixed model fit <- lmer(Reaction ~ Days + (Days | Subject), sleepstudy) # Evaluate the approximate residual degrees of freedom rdf.merMod(fit)
Adapted from lme4:::reOnly
reOnly(f, response = FALSE)reOnly(f, response = FALSE)
f |
formula |
response |
(FALSE) is there a response in the formula |
residuals for MArrayLM
## S4 method for signature 'MArrayLM' residuals(object, y, ..., type = c("response", "pearson"))## S4 method for signature 'MArrayLM' residuals(object, y, ..., type = c("response", "pearson"))
object |
MArrayLM object from dream |
y |
|
... |
other arguments, currently ignored |
type |
compute either response or pearson residuals |
results of residuals
residuals for MArrayLM2
## S4 method for signature 'MArrayLM2' residuals(object, y, type = c("response", "pearson"), ...)## S4 method for signature 'MArrayLM2' residuals(object, y, type = c("response", "pearson"), ...)
object |
MArrayLM2 object from dream |
y |
|
type |
compute either response or pearson residuals |
... |
other arguments, currently ignored |
results of residuals
Extract residuals for each gene from model fit with fitVarPartModel()
## S4 method for signature 'VarParFitList' residuals(object, ...)## S4 method for signature 'VarParFitList' residuals(object, ...)
object |
object produced by fitVarPartModel() |
... |
other arguments. |
If model is fit with missing data, residuals returns NA for entries that were missing in the original data
Residuals extracted from model fits stored in object
# load library # library(variancePartition) library(BiocParallel) # load simulated data: # geneExpr: matrix of gene expression values # info: information/metadata about each sample data(varPartData) # Specify variables to consider # Age is continuous so we model it as a fixed effect # Individual and Tissue are both categorical, so we model them as random effects form <- ~ Age + (1 | Individual) + (1 | Tissue) # Fit model modelFit <- fitVarPartModel(geneExpr, form, info) # Extract residuals of model fit res <- residuals(modelFit)# load library # library(variancePartition) library(BiocParallel) # load simulated data: # geneExpr: matrix of gene expression values # info: information/metadata about each sample data(varPartData) # Specify variables to consider # Age is continuous so we model it as a fixed effect # Individual and Tissue are both categorical, so we model them as random effects form <- ~ Age + (1 | Individual) + (1 | Tissue) # Fit model modelFit <- fitVarPartModel(geneExpr, form, info) # Extract residuals of model fit res <- residuals(modelFit)
Residuals for result of dream
residuals.MArrayLM2(object, y, ..., type = c("response", "pearson"))residuals.MArrayLM2(object, y, ..., type = c("response", "pearson"))
object |
See |
y |
|
... |
See |
type |
compute either response or pearson residuals |
Evaluates the coefficient from the linear regression of s2.post ~ sigmaSq. When there is no shrinkage, this value is 1. Values less than 1 indicate the amount of shrinkage.
shrinkageMetric(sigmaSq, s2.post)shrinkageMetric(sigmaSq, s2.post)
sigmaSq |
maximum likelihood residual variance for every gene |
s2.post |
empirical Bayes posterior estimate of residual variance for every gene |
Shrinkage metric for eBayes quantifying the amount of shrinkage that is applied to shrink the maximum likelihood residual variance to the empirical Bayes posterior estimate
Sort columns returned by extractVarPart() or fitExtractVarPartModel()
sortCols( x, FUN = median, decreasing = TRUE, last = c("Residuals", "Measurement.error"), ... ) ## S4 method for signature 'matrix' sortCols( x, FUN = median, decreasing = TRUE, last = c("Residuals", "Measurement.error"), ... ) ## S4 method for signature 'data.frame' sortCols( x, FUN = median, decreasing = TRUE, last = c("Residuals", "Measurement.error"), ... ) ## S4 method for signature 'varPartResults' sortCols( x, FUN = median, decreasing = TRUE, last = c("Residuals", "Measurement.error"), ... )sortCols( x, FUN = median, decreasing = TRUE, last = c("Residuals", "Measurement.error"), ... ) ## S4 method for signature 'matrix' sortCols( x, FUN = median, decreasing = TRUE, last = c("Residuals", "Measurement.error"), ... ) ## S4 method for signature 'data.frame' sortCols( x, FUN = median, decreasing = TRUE, last = c("Residuals", "Measurement.error"), ... ) ## S4 method for signature 'varPartResults' sortCols( x, FUN = median, decreasing = TRUE, last = c("Residuals", "Measurement.error"), ... )
x |
object returned by |
FUN |
function giving summary statistic to sort by. Defaults to median |
decreasing |
logical. Should the sorting be increasing or decreasing? |
last |
columns to be placed on the right, regardless of values in these columns |
... |
other arguments to sort |
data.frame with columns sorted by mean value, with Residuals in last column
# library(variancePartition) library(BiocParallel) # load simulated data: # geneExpr: matrix of gene expression values # info: information/metadata about each sample data(varPartData) # Specify variables to consider # Age is continuous so we model it as a fixed effect # Individual and Tissue are both categorical, so we model them as random effects form <- ~ Age + (1 | Individual) + (1 | Tissue) # Step 1: fit linear mixed model on gene expression # If categorical variables are specified, a linear mixed model is used # If all variables are modeled as continuous, a linear model is used # each entry in results is a regression model fit on a single gene # Step 2: extract variance fractions from each model fit # for each gene, returns fraction of variation attributable to each variable # Interpretation: the variance explained by each variable # after correction for all other variables varPart <- fitExtractVarPartModel(geneExpr, form, info) # violin plot of contribution of each variable to total variance # sort columns by median value plotVarPart(sortCols(varPart))# library(variancePartition) library(BiocParallel) # load simulated data: # geneExpr: matrix of gene expression values # info: information/metadata about each sample data(varPartData) # Specify variables to consider # Age is continuous so we model it as a fixed effect # Individual and Tissue are both categorical, so we model them as random effects form <- ~ Age + (1 | Individual) + (1 | Tissue) # Step 1: fit linear mixed model on gene expression # If categorical variables are specified, a linear mixed model is used # If all variables are modeled as continuous, a linear model is used # each entry in results is a regression model fit on a single gene # Step 2: extract variance fractions from each model fit # for each gene, returns fraction of variation attributable to each variable # Interpretation: the variance explained by each variable # after correction for all other variables varPart <- fitExtractVarPartModel(geneExpr, form, info) # violin plot of contribution of each variable to total variance # sort columns by median value plotVarPart(sortCols(varPart))
topTable generic
topTable generic MArrayLM
topTable generic MArrayLM2
topTable( fit, coef = NULL, number = 10, genelist = fit$genes, adjust.method = "BH", sort.by = "B", resort.by = NULL, p.value = 1, lfc = 0, confint = FALSE ) ## S4 method for signature 'MArrayLM' topTable( fit, coef = NULL, number = 10, genelist = fit$genes, adjust.method = "BH", sort.by = "p", resort.by = NULL, p.value = 1, lfc = 0, confint = FALSE ) ## S4 method for signature 'MArrayLM2' topTable( fit, coef = NULL, number = 10, genelist = fit$genes, adjust.method = "BH", sort.by = "p", resort.by = NULL, p.value = 1, lfc = 0, confint = FALSE )topTable( fit, coef = NULL, number = 10, genelist = fit$genes, adjust.method = "BH", sort.by = "B", resort.by = NULL, p.value = 1, lfc = 0, confint = FALSE ) ## S4 method for signature 'MArrayLM' topTable( fit, coef = NULL, number = 10, genelist = fit$genes, adjust.method = "BH", sort.by = "p", resort.by = NULL, p.value = 1, lfc = 0, confint = FALSE ) ## S4 method for signature 'MArrayLM2' topTable( fit, coef = NULL, number = 10, genelist = fit$genes, adjust.method = "BH", sort.by = "p", resort.by = NULL, p.value = 1, lfc = 0, confint = FALSE )
fit |
fit |
coef |
coef |
number |
number |
genelist |
genelist |
adjust.method |
adjust.method |
sort.by |
sort.by |
resort.by |
resort.by |
p.value |
p.value |
lfc |
lfc |
confint |
confint |
results of toptable
results of toptable
results of toptable
Fit linear mixed model to estimate contribution of multiple sources of variation while simultaneously correcting for all other variables. Then perform parametric bootstrap sampling to get a 95% confidence intervals for each variable for each gene.
varPartConfInf( exprObj, formula, data, REML = FALSE, useWeights = TRUE, control = vpcontrol, nsim = 1000, ... )varPartConfInf( exprObj, formula, data, REML = FALSE, useWeights = TRUE, control = vpcontrol, nsim = 1000, ... )
exprObj |
matrix of expression data (g genes x n samples), or |
formula |
specifies variables for the linear (mixed) model. Must only specify covariates, since the rows of exprObj are automatically used as a response. e.g.: |
data |
|
REML |
use restricted maximum likelihood to fit linear mixed model. default is FALSE. Strongly discourage against changing this option, but here for compatibility. |
useWeights |
if TRUE, analysis uses heteroskedastic error estimates from |
control |
control settings for |
nsim |
number of bootstrap datasets |
... |
Additional arguments for |
A linear mixed model is fit for each gene, and bootMer() is used to generate parametric bootstrap confidence intervals. use.u=TRUE is used so that the values from the random effects are used as estimated and are not re-sampled. This gives confidence intervals as if additional data were generated from these same current samples. Conversely, use.u=FALSE assumes that this dataset is a sample from a larger population. Thus it simulates based on the estimated variance parameter. This approach gives confidence intervals as if additional data were collected from the larger population from which this dataset is sampled. Overall, use.u=TRUE gives smaller confidence intervals that are appropriate in this case.
list() of where each entry is the result for a gene. Each entry is a matrix of the 95% confidence interval of the variance fraction for each variable
# load library # library(variancePartition) library(BiocParallel) # load simulated data: # geneExpr: matrix of gene expression values # info: information/metadata about each sample data(varPartData) # Specify variables to consider # Age is continuous so we model it as a fixed effect # Individual and Tissue are both categorical, so we model them as random effects form <- ~ Age + (1 | Individual) + (1 | Tissue) # Compute bootstrap confidence intervals for each variable for each gene resCI <- varPartConfInf(geneExpr[1:5, ], form, info, nsim = 100)# load library # library(variancePartition) library(BiocParallel) # load simulated data: # geneExpr: matrix of gene expression values # info: information/metadata about each sample data(varPartData) # Specify variables to consider # Age is continuous so we model it as a fixed effect # Individual and Tissue are both categorical, so we model them as random effects form <- ~ Age + (1 | Individual) + (1 | Tissue) # Compute bootstrap confidence intervals for each variable for each gene resCI <- varPartConfInf(geneExpr[1:5, ], form, info, nsim = 100)
A simulated dataset of gene expression and metadata
A simulated dataset of gene counts
A simulated dataset of gene counts
A simulated dataset of gene counts
data(varPartData) data(varPartData) data(varPartData) data(varPartData)data(varPartData) data(varPartData) data(varPartData) data(varPartData)
A dataset of 100 samples and 200 genes
A dataset of 100 samples and 200 genes
A dataset of 100 samples and 200 genes
A dataset of 100 samples and 200 genes
geneCounts gene expression in the form of RNA-seq counts
geneExpr gene expression on a continuous scale
info metadata about the study design
geneCounts gene expression in the form of RNA-seq counts
geneExpr gene expression on a continuous scale
info metadata about the study design
geneCounts gene expression in the form of RNA-seq counts
geneExpr gene expression on a continuous scale
info metadata about the study design
geneCounts gene expression in the form of RNA-seq counts
geneExpr gene expression on a continuous scale
info metadata about the study design
geneCounts gene expression in the form of RNA-seq counts
geneExpr gene expression on a continuous scale
info metadata about the study design
geneCounts gene expression in the form of RNA-seq counts
geneExpr gene expression on a continuous scale
info metadata about the study design
data(varPartData) data(varPartData)data(varPartData) data(varPartData)
A dataset of 24 samples and 19,364 genes
A dataset of 24 samples and 19,364 genes
dream() fitDefine generic vcov() for result of lmFit() and dream()
## S4 method for signature 'MArrayLM' vcov(object, vobj, coef)## S4 method for signature 'MArrayLM' vcov(object, vobj, coef)
object |
|
vobj |
|
coef |
name of coefficient to be extracted |
variance-covariance matrix
dream() fitDefine generic vcov() for result of lmFit() and dream()
## S4 method for signature 'MArrayLM2' vcov(object, vobj, coef)## S4 method for signature 'MArrayLM2' vcov(object, vobj, coef)
object |
|
vobj |
|
coef |
name of coefficient to be extracted |
variance-covariance matrix
dream() fitDefine generic vcovSqrt() for result of lmFit() and dream()
vcovSqrt(object, vobj, coef, approx = TRUE) ## S4 method for signature 'MArrayLM' vcovSqrt(object, vobj, coef, approx = TRUE) ## S4 method for signature 'MArrayLM2' vcovSqrt(object, vobj, coef, approx = TRUE)vcovSqrt(object, vobj, coef, approx = TRUE) ## S4 method for signature 'MArrayLM' vcovSqrt(object, vobj, coef, approx = TRUE) ## S4 method for signature 'MArrayLM2' vcovSqrt(object, vobj, coef, approx = TRUE)
object |
|
vobj |
|
coef |
name of coefficient to be extracted |
approx |
use fast approximation |
Computes factor of covariance matrix so that vcov(object) is the same as crossprod(vcovSqrt(object))
# load simulated data: # geneExpr: matrix of *normalized* gene expression values # info: information/metadata about each sample data(varPartData) form <- ~Batch fit <- dream(geneExpr[1:2, ], form, info) fit <- eBayes(fit) # Compute covariance directly Sigma <- vcov(fit, geneExpr[1:2, ]) # Compute factor of covariance S <- crossprod(vcovSqrt(fit, geneExpr[1:2, ]))# load simulated data: # geneExpr: matrix of *normalized* gene expression values # info: information/metadata about each sample data(varPartData) form <- ~Batch fit <- dream(geneExpr[1:2, ], form, info) fit <- eBayes(fit) # Compute covariance directly Sigma <- vcov(fit, geneExpr[1:2, ]) # Compute factor of covariance S <- crossprod(vcovSqrt(fit, geneExpr[1:2, ]))
dream()
Transform count data to log2-counts per million (logCPM), estimate the mean-variance relationship and use this to compute appropriate observation-level weights. The data are then ready for linear mixed modelling with dream(). This method is the same as limma::voom(), except that it allows random effects in the formula
voomWithDreamWeights( counts, formula, data, lib.size = NULL, normalize.method = "none", span = 0.5, weights = NULL, prior.count = 0.5, prior.count.for.weights = prior.count, plot = FALSE, save.plot = TRUE, rescaleWeightsAfter = FALSE, scaledByLib = FALSE, priorWeightsAsCounts = FALSE, BPPARAM = SerialParam(), ... )voomWithDreamWeights( counts, formula, data, lib.size = NULL, normalize.method = "none", span = 0.5, weights = NULL, prior.count = 0.5, prior.count.for.weights = prior.count, plot = FALSE, save.plot = TRUE, rescaleWeightsAfter = FALSE, scaledByLib = FALSE, priorWeightsAsCounts = FALSE, BPPARAM = SerialParam(), ... )
counts |
a numeric |
formula |
specifies variables for the linear (mixed) model. Must only specify covariates, since the rows of exprObj are automatically used as a response. e.g.: |
data |
|
lib.size |
numeric vector containing total library sizes for each sample. Defaults to the normalized (effective) library sizes in |
normalize.method |
the microarray-style normalization method to be applied to the logCPM values (if any). Choices are as for the |
span |
width of the lowess smoothing window as a proportion. Setting |
weights |
Can be a numeric matrix of individual weights of same dimensions as the |
prior.count |
average count to be added to each observation to avoid taking log of zero. The count applied to each sample is normalized by library size so given equal log CPM for a gene with zero counts across multiple samples |
prior.count.for.weights |
count added to regularize weights |
plot |
logical, should a plot of the mean-variance trend be displayed? |
save.plot |
logical, should the coordinates and line of the plot be saved in the output? |
rescaleWeightsAfter |
default = FALSE, should the output weights be scaled by the input weights |
scaledByLib |
if |
priorWeightsAsCounts |
if |
BPPARAM |
parameters for parallel evaluation |
... |
other arguments are passed to |
Adapted from voom() in limma v3.40.2
An EList object just like the result of limma::voom()
limma::voom()
# library(variancePartition) library(edgeR) library(BiocParallel) data(varPartDEdata) # normalize RNA-seq counts dge <- DGEList(counts = countMatrix) dge <- calcNormFactors(dge) # specify formula with random effect for Individual form <- ~ Disease + (1 | Individual) # compute observation weights vobj <- voomWithDreamWeights(dge[1:20, ], form, metadata) # fit dream model res <- dream(vobj, form, metadata) res <- eBayes(res) # extract results topTable(res, coef = "Disease1", number = 3)# library(variancePartition) library(edgeR) library(BiocParallel) data(varPartDEdata) # normalize RNA-seq counts dge <- DGEList(counts = countMatrix) dge <- calcNormFactors(dge) # specify formula with random effect for Individual form <- ~ Disease + (1 | Individual) # compute observation weights vobj <- voomWithDreamWeights(dge[1:20, ], form, metadata) # fit dream model res <- dream(vobj, form, metadata) res <- eBayes(res) # extract results topTable(res, coef = "Disease1", number = 3)