Package 'glmGamPoi' reference manual

Title:	Fit a Gamma-Poisson Generalized Linear Model
Description:	Fit linear models to overdispersed count data. The package can estimate the overdispersion and fit repeated models for matrix input. It is designed to handle large input datasets as they typically occur in single cell RNA-seq experiments.
Authors:	Constantin Ahlmann-Eltze [aut, cre] , Nathan Lubock [ctb] , Michael Love [ctb]
Maintainer:	Constantin Ahlmann-Eltze <[email protected]>
License:	GPL-3
Version:	1.17.3
Built:	2024-07-13 03:06:10 UTC
Source:	https://github.com/bioc/glmGamPoi

Convert glmGamPoi object to a list

Description

Convert glmGamPoi object to a list

Usage

## S3 method for class 'glmGamPoi'
as.list(x, ...)
## S3 method for class 'glmGamPoi'
as.list(x, ...)

Arguments

`x`	an object with class glmGamPoi
`...`	not used

Value

The method returns a list with the following elements:

Beta: a matrix with dimensions ⁠nrow(data) x n_coefficients⁠ where n_coefficients is based on the design argument. It contains the estimated coefficients for each gene.
overdispersions: a vector with length nrow(data). The overdispersion parameter for each gene. It describes how much more the counts vary than one would expect according to the Poisson model.
Mu: a matrix with the same dimensions as dim(data). If the calculation happened on disk, than Mu is a HDF5Matrix. It contains the estimated mean value for each gene and sample.
size_factors: a vector with length ncol(data). The size factors are the inferred correction factors for different sizes of each sample. They are also sometimes called the exposure factor.
model_matrix: a matrix with dimensions ⁠ncol(data) x n_coefficients⁠. It is build based on the design argument.

Fit a Gamma-Poisson Generalized Linear Model

Description

This function provides a simple to use interface to fit Gamma-Poisson generalized linear models. It works equally well for small scale (a single model) and large scale data (e.g. thousands of rows and columns, potentially stored on disk). The function automatically determines the appropriate size factors for each sample and efficiently finds the best overdispersion parameter for each gene.

Usage

glm_gp(
  data,
  design = ~1,
  col_data = NULL,
  reference_level = NULL,
  offset = 0,
  size_factors = c("normed_sum", "deconvolution", "poscounts", "ratio"),
  overdispersion = TRUE,
  overdispersion_shrinkage = TRUE,
  ridge_penalty = 0,
  do_cox_reid_adjustment = TRUE,
  subsample = FALSE,
  on_disk = NULL,
  use_assay = NULL,
  verbose = FALSE
)
glm_gp(
  data,
  design = ~1,
  col_data = NULL,
  reference_level = NULL,
  offset = 0,
  size_factors = c("normed_sum", "deconvolution", "poscounts", "ratio"),
  overdispersion = TRUE,
  overdispersion_shrinkage = TRUE,
  ridge_penalty = 0,
  do_cox_reid_adjustment = TRUE,
  subsample = FALSE,
  on_disk = NULL,
  use_assay = NULL,
  verbose = FALSE
)

Arguments

`data`	any matrix-like object (e.g. matrix, DelayedArray, HDF5Matrix) or anything that can be cast to a SummarizedExperiment (e.g. `MSnSet`, `eSet` etc.) with one column per sample and row per gene.
`design`	a specification of the experimental design used to fit the Gamma-Poisson GLM. It can be a `model.matrix()` with one row for each sample and one column for each coefficient. Alternatively, `design` can be a `formula`. The entries in the formula can refer to global objects, columns in the `col_data` parameter, or the `colData(data)` of `data` if it is a `SummarizedExperiment`. The third option is that `design` is a vector where each element specifies to which condition a sample belongs. Default: `design = ~ 1`, which means that all samples are treated as if they belong to the same condition. Note that this is the fasted option.
`col_data`	a dataframe with one row for each sample in `data`. Default: `NULL`.
`reference_level`	a single string that specifies which level is used as reference when the model matrix is created. The reference level becomes the intercept and all other coefficients are calculated with respect to the `reference_level`. Default: `NULL`.
`offset`	Constant offset in the model in addition to `log(size_factors)`. It can either be a single number, a vector of length `ncol(data)` or a matrix with the same dimensions as `dim(data)`. Note that if data is a DelayedArray or HDF5Matrix, `offset` must be as well. Default: `0`.
`size_factors`	in large scale experiments, each sample is typically of different size (for example different sequencing depths). A size factor is an internal mechanism of GLMs to correct for this effect. `size_factors` is either a numeric vector with positive entries that has the same lengths as columns in the data that specifies the size factors that are used. Or it can be a string that species the method that is used to estimate the size factors (one of `c("normed_sum", "deconvolution", "poscounts", "ratio")`). Note that `"normed_sum"` and `"poscounts"` are fairly simple methods and can lead to suboptimal results. For the best performance on data with many zeros, I recommend to use `size_factors = "deconvolution"` which calls `scran::calculateSumFactors()`. However, you need to separately install the `scran` package from Bioconductor for this method to work. For small datasets common for bulk RNA-seq experiments, I recommend to use `size_factors = "ratio"`, which uses the same procedure as DESeq2 and edgeR. Also note that `size_factors = 1` and `size_factors = FALSE` are equivalent. If only a single gene is given, no size factor is estimated (ie. `size_factors = 1`). Default: `"normed_sum"`.
`overdispersion`	the simplest count model is the Poisson model. However, the Poisson model assumes that $variance = mean$ . For many applications this is too rigid and the Gamma-Poisson allows a more flexible mean-variance relation ( $variance = mean + mean^2 * overdispersion$ ). `overdispersion` can either be a single boolean that indicates if an overdispersion is estimated for each gene. a numeric vector of length `nrow(data)` fixing the overdispersion to those values. the string `"global"` to indicate that one dispersion is fit across all genes. Note that `overdispersion = 0` and `overdispersion = FALSE` are equivalent and both reduce the Gamma-Poisson to the classical Poisson model. Default: `TRUE`.
`overdispersion_shrinkage`	the overdispersion can be difficult to estimate with few replicates. To improve the overdispersion estimates, we can share information across genes and shrink each individual overdispersion estimate towards a global overdispersion estimate. Empirical studies show however that the overdispersion varies based on the mean expression level (lower expression level => higher dispersion). If `overdispersion_shrinkage = TRUE`, a median trend of dispersion and expression level is fit and used to estimate the variances of a quasi Gamma Poisson model (Lund et al. 2012). Default: `TRUE`.
`ridge_penalty`	to avoid overfitting, we can penalize fits with large coefficient estimates. Instead of directly minimizing the deviance per gene ( $\sum dev(y_i, X_i b)$ ), we will minimize $\sum dev(y_i, X_i b) + N * \sum (penalty_p * b_p)^2$ . `ridge_penalty` can be a scalar in which case all parameters except the intercept are penalized. a vector which has to have the same length as columns in the model matrix a matrix with the same number of columns as columns in the model matrix. This gives maximum flexibility for expert users and allows for full Tikhonov regularization. Default: `ridge_penalty = 0`, which is internally replaced with a small positive number for numerical stability.
`do_cox_reid_adjustment`	the classical maximum likelihood estimator of the `overdisperion` is biased towards small values. McCarthy et al. (2012) showed that it is preferable to optimize the Cox-Reid adjusted profile likelihood. `do_cox_reid_adjustment` can be either be `TRUE` or `FALSE` to indicate if the adjustment is added during the optimization of the `overdispersion` parameter. Default: `TRUE`.
`subsample`	the estimation of the overdispersion is the slowest step when fitting a Gamma-Poisson GLM. For datasets with many samples, the estimation can be considerably sped up without loosing much precision by fitting the overdispersion only on a random subset of the samples. Default: `FALSE` which means that the data is not subsampled. If set to `TRUE`, at most 1,000 samples are considered. Otherwise the parameter just specifies the number of samples that are considered for each gene to estimate the overdispersion.
`on_disk`	a boolean that indicates if the dataset is loaded into memory or if it is kept on disk to reduce the memory usage. Processing in memory can be significantly faster than on disk. Default: `NULL` which means that the data is only processed in memory if `data` is an in-memory data structure.
`use_assay`	Specify which assay to use. Default: `NULL`, which means that if available 'counts' are used. Otherwise an error is thrown except if there is only a single assay.
`verbose`	a boolean that indicates if information about the individual steps are printed while fitting the GLM. Default: `FALSE`.

Details

The method follows the following steps:

The size factors are estimated.
If size_factors = "normed_sum", the column-sum for each cell is calculated and the resulting size factors are normalized so that their geometric mean is 1. If size_factors = "poscounts", a slightly adapted version of the procedure proposed by Anders and Huber (2010) in equation (5) is used. To handle the large number of zeros the geometric means are calculated for $Y + 0.5$ and ignored during the calculation of the median. Columns with all zeros get a default size factor of $0.001$ . If size_factors = "deconvolution", the method scran::calculateSumFactors() is called. If size_factors = "ratio", the unmodified procedure from Anders and Huber (2010) in equation (5) is used.
The dispersion estimates are initialized based on the moments of each row of $Y$ .
The coefficients of the model are estimated.
If all samples belong to the same condition (i.e. design = ~ 1), the betas are estimated using a quick Newton-Raphson algorithm. This is similar to the behavior of edgeR. For more complex designs, the general Fisher-scoring algorithm is used. Here, the code is based on a fork of the internal function fitBeta() from DESeq2. It does however contain some modification to make the fit more robust and faster.
The mean for each gene and sample is calculate.
Note that this step can be very IO intensive if data is or contains a DelayedArray.
The overdispersion is estimated.
The classical method for estimating the overdispersion for each gene is to maximize the Gamma-Poisson log-likelihood by iterating over each count and summing the the corresponding log-likelihood. It is however, much more efficient for genes with many small counts to work on the contingency table of the counts. Originally, this approach had already been used by Anscombe (1950). In this package, I have implemented an extension of their method that can handle general offsets.
See also overdispersion_mle().
The beta coefficients are estimated once more with the updated overdispersion estimates
The mean for each gene and sample is calculated again.

This method can handle not just in memory data, but also data stored on disk. This is essential for large scale datasets with thousands of samples, as they sometimes encountered in modern single-cell RNA-seq analysis. glmGamPoi relies on the DelayedArray and beachmat package to efficiently implement the access to the on-disk data.

Value

The method returns a list with the following elements:

Beta: a matrix with dimensions ⁠nrow(data) x n_coefficients⁠ where n_coefficients is based on the design argument. It contains the estimated coefficients for each gene.
overdispersions: a vector with length nrow(data). The overdispersion parameter for each gene. It describes how much more the counts vary than one would expect according to the Poisson model.
overdispersion_shrinkage_list: a list with additional information from the quasi-likelihood shrinkage. For details see overdispersion_shrinkage().
deviances: a vector with the deviance of the fit for each row. The deviance is a measure how well the data is fit by the model. A smaller deviance means a better fit.
Mu: a matrix with the same dimensions as dim(data). If the calculation happened on disk, than Mu is a HDF5Matrix. It contains the estimated mean value for each gene and sample.
size_factors: a vector with length ncol(data). The size factors are the inferred correction factors for different sizes of each sample. They are also sometimes called the exposure factor.
Offset: a matrix with the same dimensions as dim(data). If the calculation happened on disk, than Offset is a HDF5Matrix. It contains the log(size_factors) + offset from the function call.
data: a SummarizedExperiment that contains the input counts and the col_data
model_matrix: a matrix with dimensions ⁠ncol(data) x n_coefficients⁠. It is build based on the design argument.
design_formula: the formula that used to fit the model, or NULL otherwise
ridge_penalty: a vector with the specification of the ridge penalty.

References

McCarthy, D. J., Chen, Y., & Smyth, G. K. (2012). Differential expression analysis of multifactor RNA-Seq experiments with respect to biological variation. Nucleic Acids Research, 40(10), 4288–4297. https://doi.org/10.1093/nar/gks042.
Anders Simon, & Huber Wolfgang. (2010). Differential expression analysis for sequence count data. Genome Biology. https://doi.org/10.1016/j.jcf.2018.05.006.
Love, M. I., Huber, W., & Anders, S. (2014). Moderated estimation of fold change and dispersion for RNA-seq data with DESeq2. Genome Biology, 15(12), 550. https://doi.org/10.1186/s13059-014-0550-8.
Robinson, M. D., McCarthy, D. J., & Smyth, G. K. (2009). edgeR: A Bioconductor package for differential expression analysis of digital gene expression data. Bioinformatics, 26(1), 139–140. https://doi.org/10.1093/bioinformatics/btp616.
Lun ATL, Pagès H, Smith ML (2018). “beachmat: A Bioconductor C++ API for accessing high-throughput biological data from a variety of R matrix types.” PLoS Comput. Biol., 14(5), e1006135. doi: 10.1371/journal.pcbi.1006135..
Lund, S. P., Nettleton, D., McCarthy, D. J., & Smyth, G. K. (2012). Detecting differential expression in RNA-sequence data using quasi-likelihood with shrunken dispersion estimates. Statistical Applications in Genetics and Molecular Biology, 11(5). https://doi.org/10.1515/1544-6115.1826.
Lun ATL, Bach K and Marioni JC (2016). Pooling across cells to normalize single-cell RNA sequencing data with many zero counts. Genome Biol. 17:75 https://doi.org/10.1186/s13059-016-0947-7

Examples

 set.seed(1)
 # The simplest example
 y <- rnbinom(n = 10, mu = 3, size = 1/2.4)
 c(glm_gp(y, size_factors = FALSE))

 # Fitting a whole matrix
 model_matrix <- cbind(1, rnorm(5))
 true_Beta <- cbind(rnorm(n = 30), rnorm(n = 30, mean = 3))
 sf <- exp(rnorm(n = 5, mean = 0.7))
 model_matrix
 Y <- matrix(rnbinom(n = 30 * 5, mu = sf * exp(true_Beta %*% t(model_matrix)), size = 1/2.4),
             nrow = 30, ncol = 5)

 fit <- glm_gp(Y, design = model_matrix, size_factors = sf, verbose = TRUE)
 summary(fit)

 # Fitting a model with covariates
 data <- data.frame(fav_food = sample(c("apple", "banana", "cherry"), size = 50, replace = TRUE),
 city = sample(c("heidelberg", "paris", "new york"), size = 50, replace = TRUE),
 age = rnorm(n = 50, mean = 40, sd = 15))
 Y <- matrix(rnbinom(n = 100 * 50, mu = 3, size = 1/3.1), nrow = 100, ncol = 50)
 fit <- glm_gp(Y, design = ~ fav_food + city + age, col_data = data)
 summary(fit)

 # Specify 'ridge_penalty' to penalize extreme Beta coefficients
 fit_reg <- glm_gp(Y, design = ~ fav_food + city + age, col_data = data, ridge_penalty = 1.5)
 summary(fit_reg)


set.seed(1)
 # The simplest example
 y <- rnbinom(n = 10, mu = 3, size = 1/2.4)
 c(glm_gp(y, size_factors = FALSE))

 # Fitting a whole matrix
 model_matrix <- cbind(1, rnorm(5))
 true_Beta <- cbind(rnorm(n = 30), rnorm(n = 30, mean = 3))
 sf <- exp(rnorm(n = 5, mean = 0.7))
 model_matrix
 Y <- matrix(rnbinom(n = 30 * 5, mu = sf * exp(true_Beta %*% t(model_matrix)), size = 1/2.4),
             nrow = 30, ncol = 5)

 fit <- glm_gp(Y, design = model_matrix, size_factors = sf, verbose = TRUE)
 summary(fit)

 # Fitting a model with covariates
 data <- data.frame(fav_food = sample(c("apple", "banana", "cherry"), size = 50, replace = TRUE),
 city = sample(c("heidelberg", "paris", "new york"), size = 50, replace = TRUE),
 age = rnorm(n = 50, mean = 40, sd = 15))
 Y <- matrix(rnbinom(n = 100 * 50, mu = 3, size = 1/3.1), nrow = 100, ncol = 50)
 fit <- glm_gp(Y, design = ~ fav_food + city + age, col_data = data)
 summary(fit)

 # Specify 'ridge_penalty' to penalize extreme Beta coefficients
 fit_reg <- glm_gp(Y, design = ~ fav_food + city + age, col_data = data, ridge_penalty = 1.5)
 summary(fit_reg)

Estimate local median fit

Description

This function fits y based on x through a (weighted) median using the npoints/2 neighborhood.

Usage

loc_median_fit(
  x,
  y,
  fraction = 0.1,
  npoints = max(1, round(length(x) * fraction)),
  weighted = TRUE,
  ignore_zeros = FALSE,
  sample_fraction = 1
)
loc_median_fit(
  x,
  y,
  fraction = 0.1,
  npoints = max(1, round(length(x) * fraction)),
  weighted = TRUE,
  ignore_zeros = FALSE,
  sample_fraction = 1
)

Arguments

`x`, `y`	the x and y coordinates of the points.
`fraction`, `npoints`	the fraction / number of the points that are considered for each fit. `npoints` is the argument that is used in the end it is at least one. Default: `fraction = 0.1` and `npoints = length(x) * fraction`.
`weighted`	a boolean that indicates if a weighted median is calculated.
`ignore_zeros`	should the zeros be excluded from the fit
`sample_fraction`	use a fraction of the data to estimate the local median. Useful for extremely large datasets where the trend is well-sampled

Details

This function is low-level implementation detail and should usually not be called by the user.

Examples

  x <- runif(n = 1000, max = 4)
  y <- rpois(n = 1000, lambda = x * 10)

  plot(x, y)
  fit <- loc_median_fit(x, y, fraction = 0.1)
  fit2 <- loc_median_fit(x, y, fraction = 0.1, sample_fraction = 0.75)
  points(x, fit, col = "red")
  points(x, fit2, col = "blue")


x <- runif(n = 1000, max = 4)
  y <- rpois(n = 1000, lambda = x * 10)

  plot(x, y)
  fit <- loc_median_fit(x, y, fraction = 0.1)
  fit2 <- loc_median_fit(x, y, fraction = 0.1, sample_fraction = 0.75)
  points(x, fit, col = "red")
  points(x, fit2, col = "blue")

Estimate the Overdispersion for a Vector of Counts

Description

Estimate the Overdispersion for a Vector of Counts

Usage

overdispersion_mle(
  y,
  mean,
  model_matrix = NULL,
  do_cox_reid_adjustment = !is.null(model_matrix),
  global_estimate = FALSE,
  subsample = FALSE,
  max_iter = 200,
  verbose = FALSE
)
overdispersion_mle(
  y,
  mean,
  model_matrix = NULL,
  do_cox_reid_adjustment = !is.null(model_matrix),
  global_estimate = FALSE,
  subsample = FALSE,
  max_iter = 200,
  verbose = FALSE
)

Arguments

`y`	a numeric or integer vector or matrix with the counts for which the overdispersion is estimated
`mean`	a numeric vector of either length 1 or `length(y)` or if `y` is a matrix, a matrix with the same dimensions. Contains the predicted value for that sample. If missing: `mean(y)` / `rowMeans(y)`
`model_matrix`	a numeric matrix that specifies the experimental design. It can be produced using `stats::model.matrix()`. Default: `NULL`
`do_cox_reid_adjustment`	the classical maximum likelihood estimator of the `overdisperion` is biased towards small values. McCarthy et al. (2012) showed that it is preferable to optimize the Cox-Reid adjusted profile likelihood. `do_cox_reid_adjustment` can be either be `TRUE` or `FALSE` to indicate if the adjustment is added during the optimization of the `overdispersion` parameter. Default: `TRUE` if a model matrix is provided, otherwise `FALSE`
`global_estimate`	flag to decide if a single overdispersion for a whole matrix is calculated instead of one estimate per row. This parameter has no affect if `y` is a vector. Default: `FALSE`
`subsample`	the estimation of the overdispersion is the slowest step when fitting a Gamma-Poisson GLM. For datasets with many samples, the estimation can be considerably sped up without loosing much precision by fitting the overdispersion only on a random subset of the samples. Default: `FALSE` which means that the data is not subsampled. If set to `TRUE`, at most 1,000 samples are considered. Otherwise the parameter just specifies the number of samples that are considered for each gene to estimate the overdispersion.
`max_iter`	the maximum number of iterations for each gene
`verbose`	a boolean that indicates if information about the individual steps are printed while fitting the GLM. Default: `FALSE`.

Details

The function is optimized to be fast on many small counts. To achieve this, the frequency table of the counts is calculated and used to avoid repetitive calculations. If there are probably many unique counts the optimization is skipped. Currently the heuristic is to skip if more than half of the counts are expected to be unique. The estimation is based on the largest observed count in y.

An earlier version of this package (< 1.1.1) used a separate set of functions for the case of many small counts based on a paper by Bandara et al. (2019). However, this didn't bring a sufficient performance increase and meant an additional maintenance burden.

Value

The function returns a list with the following elements:

estimate: the numerical estimate of the overdispersion.
iterations: the number of iterations it took to calculate the result.
message: additional information about the fitting process.

Examples

 set.seed(1)
 # true overdispersion = 2.4
 y <- rnbinom(n = 10, mu = 3, size = 1/2.4)
 # estimate = 1.7
 overdispersion_mle(y)


 # true overdispersion = 0
 y <- rpois(n = 10, lambda = 3)
 # estimate = 0
 overdispersion_mle(y)
 # with different mu, overdispersion estimate changes
 overdispersion_mle(y, mean = 15)
 # Cox-Reid adjustment changes the result
 overdispersion_mle(y, mean = 15, do_cox_reid_adjustment = FALSE)


 # Many very small counts, true overdispersion = 50
 y <- rnbinom(n = 1000, mu = 0.01, size = 1/50)
 summary(y)
 # estimate = 31
 overdispersion_mle(y, do_cox_reid_adjustment = TRUE)

 # Function can also handle matrix input
 Y <- matrix(rnbinom(n = 10 * 3, mu = 4, size = 1/2.2), nrow = 10, ncol = 3)
 Y
 as.data.frame(overdispersion_mle(Y))

set.seed(1)
 # true overdispersion = 2.4
 y <- rnbinom(n = 10, mu = 3, size = 1/2.4)
 # estimate = 1.7
 overdispersion_mle(y)


 # true overdispersion = 0
 y <- rpois(n = 10, lambda = 3)
 # estimate = 0
 overdispersion_mle(y)
 # with different mu, overdispersion estimate changes
 overdispersion_mle(y, mean = 15)
 # Cox-Reid adjustment changes the result
 overdispersion_mle(y, mean = 15, do_cox_reid_adjustment = FALSE)


 # Many very small counts, true overdispersion = 50
 y <- rnbinom(n = 1000, mu = 0.01, size = 1/50)
 summary(y)
 # estimate = 31
 overdispersion_mle(y, do_cox_reid_adjustment = TRUE)

 # Function can also handle matrix input
 Y <- matrix(rnbinom(n = 10 * 3, mu = 4, size = 1/2.2), nrow = 10, ncol = 3)
 Y
 as.data.frame(overdispersion_mle(Y))

Shrink the overdispersion estimates

Description

Low-level function to shrink a set of overdispersion estimates following the quasi-likelihood and Empirical Bayesian framework.

Usage

overdispersion_shrinkage(
  disp_est,
  gene_means,
  df,
  disp_trend = TRUE,
  ql_disp_trend = NULL,
  ...,
  verbose = FALSE
)
overdispersion_shrinkage(
  disp_est,
  gene_means,
  df,
  disp_trend = TRUE,
  ql_disp_trend = NULL,
  ...,
  verbose = FALSE
)

Arguments

`disp_est`	vector of overdispersion estimates
`gene_means`	vector of average gene expression values. Used to fit `disp_trend` if that is `NULL`.
`df`	degrees of freedom for estimating the Empirical Bayesian variance prior. Can be length 1 or same length as `disp_est` and `gene_means`.
`disp_trend`	vector with the dispersion trend. If `NULL` or `TRUE` the dispersion trend is fitted using a (weighted) local median fit. Default: `TRUE`.
`ql_disp_trend`	a logical to indicate if a second abundance trend using splines is fitted for the quasi-likelihood dispersions. Default: `NULL` which means that the extra fit is only done if enough observations are present.
`...`	additional parameters for the `loc_median_fit()` function
`verbose`	a boolean that indicates if information about the individual steps are printed while fitting the GLM. Default: `FALSE`.

Details

The function goes through the following steps

Fit trend between overdispersion MLE's and the average gene expression. Per default it uses the loc_median_fit() function.
Convert the overdispersion MLE's to quasi-likelihood dispersion estimates by fixing the trended dispersion as the "true" dispersion value: $disp_{ql} = (1 + mu * disp_{mle}) / (1 + mu * disp_{trend})$
Shrink the quasi-likelihood dispersion estimates using Empirical Bayesian variance shrinkage (see Smyth 2004).

Value

the function returns a list with the following elements

dispersion_trend: the dispersion trend provided by disp_trend or the local median fit.
ql_disp_estimate: the quasi-likelihood dispersion estimates based on the dispersion trend, disp_est, and gene_means
ql_disp_trend: the ql_disp_estimate still might show a trend with respect to gene_means. If ql_disp_trend = TRUE a spline is used to remove this secondary trend. If ql_disp_trend = FALSE it corresponds directly to the dispersion prior
ql_disp_shrunken: the shrunken quasi-likelihood dispersion estimates. They are shrunken towards ql_disp_trend.
ql_df0: the degrees of freedom of the empirical Bayesian shrinkage. They correspond to spread of the ql_disp_estimate's

References

Lund, S. P., Nettleton, D., McCarthy, D. J., & Smyth, G. K. (2012). Detecting differential expression in RNA-sequence data using quasi-likelihood with shrunken dispersion estimates. Statistical Applications in Genetics and Molecular Biology, 11(5). https://doi.org/10.1515/1544-6115.1826.
Smyth, G. K. (2004). Linear models and empirical bayes methods for assessing differential expression in microarray experiments. Statistical Applications in Genetics and Molecular Biology, 3(1). https://doi.org/10.2202/1544-6115.1027

Examples

 Y <- matrix(rnbinom(n = 300 * 4, mu = 6, size = 1/4.2), nrow = 300, ncol = 4)
 disps <- sapply(seq_len(nrow(Y)), function(idx){
   overdispersion_mle(Y[idx, ])$estimate
 })
 shrink_list <- overdispersion_shrinkage(disps, rowMeans(Y), df = ncol(Y) - 1,
                                         disp_trend = FALSE, ql_disp_trend = FALSE)

 plot(rowMeans(Y), shrink_list$ql_disp_estimate)
 lines(sort(rowMeans(Y)), shrink_list$ql_disp_trend[order(rowMeans(Y))], col = "red")
 points(rowMeans(Y), shrink_list$ql_disp_shrunken, col = "blue", pch = 16, cex = 0.5)


Y <- matrix(rnbinom(n = 300 * 4, mu = 6, size = 1/4.2), nrow = 300, ncol = 4)
 disps <- sapply(seq_len(nrow(Y)), function(idx){
   overdispersion_mle(Y[idx, ])$estimate
 })
 shrink_list <- overdispersion_shrinkage(disps, rowMeans(Y), df = ncol(Y) - 1,
                                         disp_trend = FALSE, ql_disp_trend = FALSE)

 plot(rowMeans(Y), shrink_list$ql_disp_estimate)
 lines(sort(rowMeans(Y)), shrink_list$ql_disp_trend[order(rowMeans(Y))], col = "red")
 points(rowMeans(Y), shrink_list$ql_disp_shrunken, col = "blue", pch = 16, cex = 0.5)

Predict 'link' or 'response' values for Gamma-Poisson GLMs

Description

Predict mu (i.e., type = "response") or log(mu) (i.e., type = "link") from a 'glmGamPoi' fit (created by glm_gp(...)) with the corresponding estimate of the standard error. If newdata is NULL, mu is returned for the original input data.

Usage

## S3 method for class 'glmGamPoi'
predict(
  object,
  newdata = NULL,
  type = c("link", "response"),
  se.fit = FALSE,
  offset = mean(object$Offset),
  on_disk = NULL,
  verbose = FALSE,
  ...
)
## S3 method for class 'glmGamPoi'
predict(
  object,
  newdata = NULL,
  type = c("link", "response"),
  se.fit = FALSE,
  offset = mean(object$Offset),
  on_disk = NULL,
  verbose = FALSE,
  ...
)

Arguments

`object`	a `glmGamPoi` fit object (produced by `glm_gp()`).
`newdata`	a specification of the new data for which the expression for each gene is predicted. `newdata` should be a data.frame if the original fit was specified with a `formula`, provide a `data.frame` with one column for each variable in the formula. For example, if `glm_gp(se, design = ~ age + batch + treatment)`, then the data.frame needs a `age`, `batch`, and `treatment` column that contain the same data types as the original fit. vector if the original fit was specified using a vector, you need to again provide a vector with the same format. matrix if `newdata` is a matrix, it is applied directly as `Mu <- exp(object$Beta %*% t(newdata) + object$offset_matrix)`. So make sure, that it is constructed correctly. NULL if `newdata` is `NULL`, the predicted values for the original input data are returned.
`type`	either 'link' or 'response'. The default is 'link', which returns the predicted values before the link function (`exp()`) is applied. Thus, the values can be positive and negative numbers. However, often the predicted values are easier to interpret after the link function is applied (i.e., type = "response"), because then the values are on the same scale as the original counts.
`se.fit`	boolean that indicates if in addition to the mean the standard error of the mean is returned.
`offset`	count models (in particular for sequencing experiments) usually have a sample specific size factor (`⁠offset = log(size factor)⁠`). It defines how big we expect the predicted results are. If `newdata` is `NULL`, the `offset` is ignored, because the `predict()` returns a result based on the pre-calculated `object$Mu`. If `newdata` is not `NULL`, by default the `offset` is `mean(object$Offset)`, which puts the in the same size as the average sample.
`on_disk`	a boolean that indicates if the results are `HDF5Matrix`'s from the `HDF5Array` package. If `newdata` is `NULL`, `on_disk` is ignored. Otherwise, if `on_disk = NULL`, the result is calculated on disk depending if `offset` is stored on disk.
`verbose`	a boolean that indicates if information about the individual steps are printed while predicting. Default: `FALSE`.
`...`	currently ignored.

Details

For se.fit = TRUE, the function sticks very close to the behavior of stats::predict.glm() for fits from MASS::glm.nb().

Note: If type = "link", the results are computed using the natural logarithm as the link function. This differs from the lfc estimate provided by test_de, which are on the log2 scale.

Value

If se.fit == FALSE, a matrix with dimensions ⁠nrow(object$data) x nrow(newdata)⁠.
If se.fit == TRUE, a list with three entries

fit: the predicted values as a matrix with dimensions ⁠nrow(object$data) x nrow(newdata)⁠. This is what would be returned if se.fit == FALSE.
se.fit: the associated standard errors for each fit. Also a matrix with dimensions ⁠nrow(object$data) x nrow(newdata)⁠.
residual.scale: Currently fixed to 1. In the future, this might become the values from object$overdispersion_shrinkage_list$ql_disp_shrunken.

Examples


 set.seed(1)
 # The simplest example
 y <- rnbinom(n = 10, mu = 3, size = 1/2.4)
 fit <- glm_gp(y, size_factors = FALSE)
 predict(fit, type = "response")
 predict(fit, type = "link", se.fit = TRUE)


 # Fitting a whole matrix
 model_matrix <- cbind(1, rnorm(5))
 true_Beta <- cbind(rnorm(n = 30), rnorm(n = 30, mean = 3))
 sf <- exp(rnorm(n = 5, mean = 0.7))
 model_matrix
 Y <- matrix(rnbinom(n = 30 * 5, mu = sf * exp(true_Beta %*% t(model_matrix)), size = 1/2.4),
             nrow = 30, ncol = 5)
 fit <- glm_gp(Y, design = model_matrix, size_factors = sf, verbose = TRUE)

 head(predict(fit, type = "response"))
 pred <- predict(fit, type = "link", se.fit = TRUE, verbose = TRUE)
 head(pred$fit)
 head(pred$se.fit)


 # Fitting a model with covariates
 data <- data.frame(fav_food = sample(c("apple", "banana", "cherry"), size = 50, replace = TRUE),
                    city = sample(c("heidelberg", "paris", "new york"), size = 50, replace = TRUE),
                    age = rnorm(n = 50, mean = 40, sd = 15))
 Y <- matrix(rnbinom(n = 4 * 50, mu = 3, size = 1/3.1), nrow = 4, ncol = 50)
 fit <- glm_gp(Y, design = ~ fav_food + city + age, col_data = data)
 predict(fit)[, 1:3]

 nd <- data.frame(fav_food = "banana", city = "paris", age = 29)
 predict(fit, newdata = nd)

 nd <- data.frame(fav_food = "banana", city = "paris", age = 29:40)
 predict(fit, newdata = nd, se.fit = TRUE, type = "response")


set.seed(1)
 # The simplest example
 y <- rnbinom(n = 10, mu = 3, size = 1/2.4)
 fit <- glm_gp(y, size_factors = FALSE)
 predict(fit, type = "response")
 predict(fit, type = "link", se.fit = TRUE)


 # Fitting a whole matrix
 model_matrix <- cbind(1, rnorm(5))
 true_Beta <- cbind(rnorm(n = 30), rnorm(n = 30, mean = 3))
 sf <- exp(rnorm(n = 5, mean = 0.7))
 model_matrix
 Y <- matrix(rnbinom(n = 30 * 5, mu = sf * exp(true_Beta %*% t(model_matrix)), size = 1/2.4),
             nrow = 30, ncol = 5)
 fit <- glm_gp(Y, design = model_matrix, size_factors = sf, verbose = TRUE)

 head(predict(fit, type = "response"))
 pred <- predict(fit, type = "link", se.fit = TRUE, verbose = TRUE)
 head(pred$fit)
 head(pred$se.fit)


 # Fitting a model with covariates
 data <- data.frame(fav_food = sample(c("apple", "banana", "cherry"), size = 50, replace = TRUE),
                    city = sample(c("heidelberg", "paris", "new york"), size = 50, replace = TRUE),
                    age = rnorm(n = 50, mean = 40, sd = 15))
 Y <- matrix(rnbinom(n = 4 * 50, mu = 3, size = 1/3.1), nrow = 4, ncol = 50)
 fit <- glm_gp(Y, design = ~ fav_food + city + age, col_data = data)
 predict(fit)[, 1:3]

 nd <- data.frame(fav_food = "banana", city = "paris", age = 29)
 predict(fit, newdata = nd)

 nd <- data.frame(fav_food = "banana", city = "paris", age = 29:40)
 predict(fit, newdata = nd, se.fit = TRUE, type = "response")

Pretty print the result from glm_gp()

Description

Pretty print the result from glm_gp()

Usage

## S3 method for class 'glmGamPoi'
print(x, ...)

## S3 method for class 'glmGamPoi'
format(x, ...)

## S3 method for class 'glmGamPoi'
summary(object, ...)

## S3 method for class 'summary.glmGamPoi'
print(x, ...)

## S3 method for class 'summary.glmGamPoi'
format(x, ...)
## S3 method for class 'glmGamPoi'
print(x, ...)

## S3 method for class 'glmGamPoi'
format(x, ...)

## S3 method for class 'glmGamPoi'
summary(object, ...)

## S3 method for class 'summary.glmGamPoi'
print(x, ...)

## S3 method for class 'summary.glmGamPoi'
format(x, ...)

Arguments

`x`	the glmGamPoi object
`...`	additional parameters, currently ignored
`object`	the glmGamPoi object that is summarized

Value

The print() methods return the object x. The format() method returns a string. The summary() method returns an object of class summary.glmGamPoi.

Create a 'SingleCellExperiment' containing pseudo-bulk samples

Description

Create a 'SingleCellExperiment' containing pseudo-bulk samples

Usage

pseudobulk(
  data,
  group_by,
  ...,
  aggregation_functions = list(counts = "rowSums2", .default = "rowMeans2"),
  col_data = NULL,
  make_colnames = TRUE,
  verbose = TRUE
)
pseudobulk(
  data,
  group_by,
  ...,
  aggregation_functions = list(counts = "rowSums2", .default = "rowMeans2"),
  col_data = NULL,
  make_colnames = TRUE,
  verbose = TRUE
)

Arguments

`data`	a 'SingleCellExperiment' or an object of a related class
`group_by`	an unquoted expression that can refer to columns in the 'colData()'. All observations with the same factor level are aggregated. The argument follows the same logic as `dplyr::group_by()`. The argument must wrapped using `vars()`.
`...`	named expressions that summarize columns in 'colData()'. Each expression must produce a value of length 1. The arguments follow the same logic as `dplyr::summarize()`.
`aggregation_functions`	a named list with functions that are used to aggregate the assays in the `data`.
`col_data`	additional data with `ncol(data)` rows. The `group_by` and named arguments can refer to the columns of the `col_data` in addition to the columns in `colData(data)` (assuming `data` is a `SummarizedExperiment`).
`make_colnames`	a boolean that decides if the column names are the concatenated values of `group_by`. Default: `TRUE`
`verbose`	a boolean that indicates if information about the process are printed Default: `TRUE`.

Value

a SingleCellExperiment object

Examples

 library(SingleCellExperiment)
 data <- data.frame(sample = sample(c("samp1", "samp2", "samp3"), size = 50, replace = TRUE),
       celltype = sample(c("T cells", "B cells", "Macrophages"), size = 50, replace = TRUE),
       size = rnorm(n = 50, mean = 40, sd = 15))
 Y <- matrix(rnbinom(n = 100 * 50, mu = 3, size = 1/3.1), nrow = 100, ncol = 50)
 sce <- SingleCellExperiment(Y, colData = data)
 aggr_sce <- pseudobulk(sce, group_by = vars(sample, celltype), size = mean(size))
 aggr_sce
 colData(aggr_sce)

library(SingleCellExperiment)
 data <- data.frame(sample = sample(c("samp1", "samp2", "samp3"), size = 50, replace = TRUE),
       celltype = sample(c("T cells", "B cells", "Macrophages"), size = 50, replace = TRUE),
       size = rnorm(n = 50, mean = 40, sd = 15))
 Y <- matrix(rnbinom(n = 100 * 50, mu = 3, size = 1/3.1), nrow = 100, ncol = 50)
 sce <- SingleCellExperiment(Y, colData = data)
 aggr_sce <- pseudobulk(sce, group_by = vars(sample, celltype), size = mean(size))
 aggr_sce
 colData(aggr_sce)

Extract Residuals of Gamma Poisson Model

Description

Extract Residuals of Gamma Poisson Model

Usage

## S3 method for class 'glmGamPoi'
residuals(
  object,
  type = c("deviance", "pearson", "randomized_quantile", "working", "response"),
  ...
)
## S3 method for class 'glmGamPoi'
residuals(
  object,
  type = c("deviance", "pearson", "randomized_quantile", "working", "response"),
  ...
)

Arguments

`object`	a fit of type `glmGamPoi`. It is usually produced with a call to `glm_gp()`.
`type`	the type of residual that is calculated. See details for more information. Default: `"deviance"`.
`...`	currently ignored.

Details

This method can calculate a range of different residuals:

deviance

The deviance for the Gamma-Poisson model is

$dev = 2 * (1/theta * \log((1 + m * theta) / (1 + y * theta)) - y \log((m + y * theta) / (y + y * m * theta)))$

and the residual accordingly is

$res = sign(y - m) \sqrt{dev}.$

pearson

The Pearson residual is $res = (y - m) / \sqrt{m + m^2 * theta}.$

randomized_quantile

The randomized quantile residual was originally developed by Dunn & Smyth, 1995. Please see that publication or statmod::qresiduals() for more information.

working

The working residuals are $res = (y - m) / m$ .

response

The response residuals are $res = y - m$

Value

a matrix with the same size as fit$data. If fit$data contains a DelayedArray than the result will be a DelayedArray as well.

Solve the equation Y = A B for A or B

Description

Solve the equation Y = A B for A or B

Usage

solve_lm_for_A(Y, B, w = NULL)

solve_lm_for_B(Y, A, w = NULL)
solve_lm_for_A(Y, B, w = NULL)

solve_lm_for_B(Y, A, w = NULL)

Arguments

`Y`	the left side of the equation
`w`	a vector with weights. If `NULL` it is ignored, otherwise it must be of length 1 or have the same length as columns in `Y`. Default: `NULL`
`A`, `B`	the known matrix on the right side of the equation

Test for Differential Expression

Description

Conduct a quasi-likelihood ratio test for a Gamma-Poisson fit.

Usage

test_de(
  fit,
  contrast,
  reduced_design = NULL,
  full_design = fit$model_matrix,
  subset_to = NULL,
  pseudobulk_by = NULL,
  pval_adjust_method = "BH",
  sort_by = NULL,
  decreasing = FALSE,
  n_max = Inf,
  max_lfc = 10,
  compute_lfc_se = FALSE,
  verbose = FALSE
)
test_de(
  fit,
  contrast,
  reduced_design = NULL,
  full_design = fit$model_matrix,
  subset_to = NULL,
  pseudobulk_by = NULL,
  pval_adjust_method = "BH",
  sort_by = NULL,
  decreasing = FALSE,
  n_max = Inf,
  max_lfc = 10,
  compute_lfc_se = FALSE,
  verbose = FALSE
)

Arguments

`fit`	object of class `glmGamPoi`. Usually the result of calling `glm_gp(data, ...)`
`contrast`	The contrast to test. Can be a single column name (quoted or as a string) that is removed from the full model matrix of `fit`. Or a complex contrast comparing two or more columns: e.g. `A - B`, `"A - 3 * B"`, `(A + B) / 2 - C` etc. For complicated experimental design that involved nested conditions, you specify the condition level to compare using the `cond()` helper function. Only one of `contrast` or `reduced_design` must be specified.
`reduced_design`	a specification of the reduced design used as a comparison to see what how much better `fit` describes the data. Analogous to the `design` parameter in `glm_gp()`, it can be either a `formula`, a `model.matrix()`, or a `vector`. Only one of `contrast` or `reduced_design` must be specified.
`full_design`	option to specify an alternative `full_design` that can differ from `fit$model_matrix`. Can be a `formula` or a `matrix`. Default: `fit$model_matrix`
`subset_to`	a vector with the same length as `ncol(fit$data)` or an expression that evaluates to such a vector. The expression can reference columns from `colData(fit$data)`. A typical use case in single cell analysis would be to subset to a specific cell type (e.g. `subset_to = cell_type == "T-cells"`). Note that if this argument is set a new the model for the `full_design` is re-fit. Default: `NULL` which means that the data is not subset.
`pseudobulk_by`	DEPRECTATED, please use the pseudobulk function instead. A vector with the same length as `ncol(fit$data)` that is used to split the columns into different groups (calls `split()`). `pseudobulk_by` can also be an expression that evaluates to a vector. The expression can reference columns from `colData(fit$data)`. The counts are summed across the groups to create "pseudobulk" samples. This is typically used in single cell analysis if the cells come from different samples to get a proper estimate of the differences. This is particularly powerful in combination with the `subset_to` parameter to analyze differences between samples for subgroups of cells. Note that this does a fresh fit for both the full and the reduced design. Default: `NULL` which means that the data is not aggregated.
`pval_adjust_method`	one of the p-value adjustment method from p.adjust.methods. Default: `"BH"`.
`sort_by`	the name of the column or an expression used to sort the result. If `sort_by` is `NULL` the table is not sorted. Default: `NULL`
`decreasing`	boolean to decide if the result is sorted increasing or decreasing order. Default: `FALSE`.
`n_max`	the maximum number of rows to return. Default: `Inf` which means that all rows are returned
`max_lfc`	set the maximum absolute log fold change that is returned. Large log fold changes occur for lowly expressed genes because the ratio of two small numbers can be impractically large. For example, limiting the range of log fold changes can clarify the patterns in a volcano plot. Default: `10` which corresponds to a thousand-fold (2^10) increase in expression.
`compute_lfc_se`	Compute standard errors for the log fold changes, and add a column `lfc_se` to the returned dataframe. Only has an effect when using `contrast` instead of `reduced_design`. Default: `FALSE`
`verbose`	a boolean that indicates if information about the individual steps are printed while fitting the GLM. Default: `FALSE`.

Details

The cond() helper function simplifies the specification of a contrast for complex experimental designs. Instead of working out which combination of coefficients corresponds to a research question, you can simply specify the two conditions that you want to compare.

You can only call the cond function inside the contrast argument. The arguments are the selected factor levels for each covariate. To compare two conditions, simply subtract the two cond calls. Internally, the package calls model.matrix using the provided values and the original formula from the fit to produce a vector. Subtracting two of these vectors produces a contrast vector. Missing covariates are filled with the first factor level or zero for numerical covariates.

Value

a data.frame with the following columns

name: the rownames of the input data
pval: the p-values of the quasi-likelihood ratio test
adj_pval: the adjusted p-values returned from p.adjust()
f_statistic: the F-statistic: $F = (Dev_{full} - Dev_{red}) / (df_1 * disp_{ql-shrunken})$
df1: the degrees of freedom of the test: ncol(design) - ncol(reduced_design)
df2: the degrees of freedom of the fit: ncol(data) - ncol(design) + df_0
lfc: the log2-fold change. If the alternative model is specified by reduced_design will be NA.
lfc_se: the standard error of the log2-fold change. Only calculated if compute_lfc_se == TRUE.

References

Lund, S. P., Nettleton, D., McCarthy, D. J., & Smyth, G. K. (2012). Detecting differential expression in RNA-sequence data using quasi-likelihood with shrunken dispersion estimates. Statistical Applications in Genetics and Molecular Biology, 11(5). https://doi.org/10.1515/1544-6115.1826.

Examples

 # Make Data
 Y <- matrix(rnbinom(n = 30 * 100, mu = 4, size = 0.3), nrow = 30, ncol = 100)
 annot <- data.frame(mouse = sample(LETTERS[1:6], size = 100, replace = TRUE),
        celltype = sample(c("Tcell", "Bcell", "Macrophages"), size = 100, replace = TRUE),
        cont1 = rnorm(100), cont2 = rnorm(100, mean = 30))
 annot$condition <- ifelse(annot$mouse %in% c("A", "B", "C"), "ctrl", "treated")
 head(annot)
 se <- SummarizedExperiment::SummarizedExperiment(Y, colData = annot)

 # Fit model
 fit <- glm_gp(se, design = ~ condition + celltype + cont1 + cont2)
 # Test with reduced design
 res <- test_de(fit, reduced_design = ~ celltype + cont1 + cont2)
 head(res)
 # Test with contrast argument, the results are identical
 res2 <- test_de(fit, contrast = conditiontreated)
 head(res2)
 # Test with explicit specification of the conditions
 # The results are still identical
 res3 <- test_de(fit, contrast = cond(condition = "treated", celltype = "Bcell") -
                                    cond(condition = "ctrl", celltype = "Bcell"))
 head(res3)


 # The column names of fit$Beta are valid variables in the contrast argument
 colnames(fit$Beta)
 # You can also have more complex contrasts:
 # the following compares cont1 vs cont2:
 test_de(fit, cont1 - cont2, n_max = 4)
 # You can also sort the output
 test_de(fit, cont1 - cont2, n_max = 4,
         sort_by = "pval")
 test_de(fit, cont1 - cont2, n_max = 4,
         sort_by = - abs(f_statistic))

 # If the data has multiple samples, it is a good
 # idea to aggregate the cell counts by samples.
 # This is called forming a "pseudobulk".
 se_reduced <- pseudobulk(se, group_by = vars(mouse, condition, celltype),
                          cont1 = mean(cont1), cont2 = min(cont2))
 fit_reduced <- glm_gp(se_reduced, design = ~ condition + celltype)
 test_de(fit_reduced, contrast = "conditiontreated", n_max = 4)
 test_de(fit_reduced, contrast = cond(condition = "treated", celltype = "Macrophages") -
                                      cond(condition = "ctrl", celltype = "Macrophages"),
         n_max = 4)


# Make Data
 Y <- matrix(rnbinom(n = 30 * 100, mu = 4, size = 0.3), nrow = 30, ncol = 100)
 annot <- data.frame(mouse = sample(LETTERS[1:6], size = 100, replace = TRUE),
        celltype = sample(c("Tcell", "Bcell", "Macrophages"), size = 100, replace = TRUE),
        cont1 = rnorm(100), cont2 = rnorm(100, mean = 30))
 annot$condition <- ifelse(annot$mouse %in% c("A", "B", "C"), "ctrl", "treated")
 head(annot)
 se <- SummarizedExperiment::SummarizedExperiment(Y, colData = annot)

 # Fit model
 fit <- glm_gp(se, design = ~ condition + celltype + cont1 + cont2)
 # Test with reduced design
 res <- test_de(fit, reduced_design = ~ celltype + cont1 + cont2)
 head(res)
 # Test with contrast argument, the results are identical
 res2 <- test_de(fit, contrast = conditiontreated)
 head(res2)
 # Test with explicit specification of the conditions
 # The results are still identical
 res3 <- test_de(fit, contrast = cond(condition = "treated", celltype = "Bcell") -
                                    cond(condition = "ctrl", celltype = "Bcell"))
 head(res3)


 # The column names of fit$Beta are valid variables in the contrast argument
 colnames(fit$Beta)
 # You can also have more complex contrasts:
 # the following compares cont1 vs cont2:
 test_de(fit, cont1 - cont2, n_max = 4)
 # You can also sort the output
 test_de(fit, cont1 - cont2, n_max = 4,
         sort_by = "pval")
 test_de(fit, cont1 - cont2, n_max = 4,
         sort_by = - abs(f_statistic))

 # If the data has multiple samples, it is a good
 # idea to aggregate the cell counts by samples.
 # This is called forming a "pseudobulk".
 se_reduced <- pseudobulk(se, group_by = vars(mouse, condition, celltype),
                          cont1 = mean(cont1), cont2 = min(cont2))
 fit_reduced <- glm_gp(se_reduced, design = ~ condition + celltype)
 test_de(fit_reduced, contrast = "conditiontreated", n_max = 4)
 test_de(fit_reduced, contrast = cond(condition = "treated", celltype = "Macrophages") -
                                      cond(condition = "ctrl", celltype = "Macrophages"),
         n_max = 4)

Quote grouping variables

Description

Quote grouping variables

Usage

vars(...)
vars(...)

Arguments

...

the quoted expression

Package 'glmGamPoi'

Help Index

Convert glmGamPoi object to a list

Description

Usage

Arguments

Value

Fit a Gamma-Poisson Generalized Linear Model

Description

Usage

Arguments

Details

Value

References

See Also

Examples

Estimate local median fit

Description

Usage

Arguments

Details

See Also

Examples

Estimate the Overdispersion for a Vector of Counts

Description

Usage

Arguments

Details

Value

See Also

Examples

Shrink the overdispersion estimates

Description

Usage

Arguments

Details

Value

References

See Also

Examples

Predict 'link' or 'response' values for Gamma-Poisson GLMs

Description

Usage

Arguments

Details

Value

See Also

Examples

Pretty print the result from glm_gp()

Description

Usage

Arguments

Value

Create a 'SingleCellExperiment' containing pseudo-bulk samples

Description

Usage

Arguments

Value

Examples

Extract Residuals of Gamma Poisson Model

Description

Usage

Arguments

Details

Value

See Also

Solve the equation Y = A B for A or B

Description

Usage

Arguments

Test for Differential Expression

Description

Usage

Arguments

Details

Value

References

See Also

Examples

Quote grouping variables