Package 'BioNet'

Title: Routines for the functional analysis of biological networks
Description: This package provides functions for the integrated analysis of protein-protein interaction networks and the detection of functional modules. Different datasets can be integrated into the network by assigning p-values of statistical tests to the nodes of the network. E.g. p-values obtained from the differential expression of the genes from an Affymetrix array are assigned to the nodes of the network. By fitting a beta-uniform mixture model and calculating scores from the p-values, overall scores of network regions can be calculated and an integer linear programming algorithm identifies the maximum scoring subnetwork.
Authors: Marcus Dittrich and Daniela Beisser
Maintainer: Marcus Dittrich <[email protected]>
License: GPL (>= 2)
Version: 1.67.0
Built: 2024-11-19 03:26:53 UTC
Source: https://github.com/bioc/BioNet

Help Index


Routines for the functional analysis of biological networks

Description

This package provides functions for the integrated analysis of biological networks and the detection of functional modules. Different datasets can be integrated into the network by assigning p-values derived from statistical tests to the nodes of the network. E.g. p-values obtained from the differential expression of genes from an Affymetrix array are assigned to the nodes of an protein-protein interaction network. By fitting a beta-uniform mixture model and calculating scores from the p-values, overall scores of network regions can be calculated and an integer linear programming algorithm identifies the maximum scoring subnetwork.

Details

Package: BioNet
Type: Package
Version: 1.29.1
Date: 2015-09-11
License: GPL (>=2)
LazyLoad: yes

Author(s)

Marcus Dittrich, Daniela Beisser

Maintainer: Marcus Dittrich <[email protected]>

References

M. T. Dittrich, G. W. Klau, A. Rosenwald, T. Dandekar and T. Mueller (2008) Identifying functional modules in protein-protein interaction networks: an integrated exact approach. (ISMB2008) Bioinformatics 24: 13. i223-i231 Jul.

D. Beisser, G. W. Klau, T. Dandekar, T. Mueller and M. Dittrich (2010) BioNet: an R-package for the Functional Analysis of Biological Networks. Bioinformatics 26:08. 1129-1130 Apr.


Aggregate several p-values into one p-value

Description

The function aggregates several p-values into one p-value of p-values based on the order statistics of p-values. An overall p-value is given by the ith order statistic.

Usage

aggrPvals(pval.matrix, order, plot=TRUE)

Arguments

pval.matrix

Numeric matrix of p-values, columns represent different sets of p-values

order

Numeric constant, the order statistic that is used for the aggregation.

plot

Boolean value whether to plot p-value distributions.

Value

Aggregated p-value of the given order.

Author(s)

Daniela Beisser

Examples

data(pvaluesExample)
aggrPvals(pval.matrix=pvaluesExample, order=2)

Fitting a beta-uniform mixture model to p-value distribution

Description

The function fits a beta-uniform mixture model to a given p-value distribution.

Usage

bumOptim(x, starts=1, labels=NULL)

Arguments

x

Numerical vector of p-values, has to be named with the gene names or the gene names can be given in the labels paramater.

starts

Number of start points for the optimization.

labels

Gene names for the p-values.

Value

List of class fb with the following elements:

lambda

Fitted parameter lambda for the beta-uniform mixture model.

a

Fitted parameter a for the beta-uniform mixture model.

negLL

Negative log-likelihood.

pvalues

P-value vector.

Author(s)

Marcus Dittrich and Daniela Beisser

References

M. T. Dittrich, G. W. Klau, A. Rosenwald, T. Dandekar, T. Mueller (2008) Identifying functional modules in protein-protein interaction networks: an integrated exact approach. (ISMB2008) Bioinformatics, 24: 13. i223-i231 Jul.

S. Pounds, S.W. Morris (2003) Estimating the occurrence of false positives and false negatives in microarray studies by approximating and partitioning the empirical distribution of p-values. Bioinformatics, 19(10): 1236-1242.

See Also

fitBumModel, plot.bum, hist.bum

Examples

data(pvaluesExample)
pvals <- pvaluesExample[,1]
bum <- bumOptim(x=pvals, starts=10)
bum

Compare parameters of two networks

Description

The function compares the following parameters of two networks: diameter, average degree, degree exponent, average path length and plots the cumulative degree distributions. The networks have to be connected components.

Usage

compareNetworks(network1, network2, plot=TRUE)

Arguments

network1

Network graphNEL or igraph format.

network2

Second network in graphNEL or igraph format, or subnetwork drawn from first network.

plot

Boolean value, whether to plot the cumulative degree distributions.

Value

A vector of network parameters is returned:

diam.network1

Network diameter

diam.network2

Diameter of the subnetwork

av.degree.network1

Average degree of the network

av.degree.network2

Average degree of the subnetwork

degree.exponent.network1

Degree exponent of the network

degree.exponent.network2

Degree exponent of the subnetwork

av.path.length.network1

Average path lenght of the network

av.path.length.network2

Average path length of the subnetwork

Author(s)

Daniela Beisser

Examples

library(DLBCL)
data(interactome)
subnet1 <- largestComp(subNetwork(nodes(interactome)[1:100], interactome))
subnet2 <- largestComp(subNetwork(nodes(interactome)[101:200], interactome))
compareNetworks(network1=subnet1, network2=subnet2)

Calculation of a consensus score for a network

Description

The function calculates consensus scores for a network, given a list of replicate modules.

Usage

consensusScores(modules, network, ro=length(modules)/2)

Arguments

modules

Calculated modules from pseudo-replicates of expression values in igraph or graphNEL format.

network

Interaction network, which shoupld be scores. In igraph or graphNEL format

ro

Threshold which is subtracted from the scores to obtain positive and negative value. The default value is half of the number of replicates.

Value

A result list is returned, consisting of:

N.scores

Numerical vector node scores.

E.scores

Numerical vector edge scores.

N.frequencies

Numerical vector node frequencies from the replicate modules.

E.frequencies

Numerical vector edge frequencies from the replicate modules.

Author(s)

Daniela Beisser

Examples

library(DLBCL)
data(interactome)
network <- interactome
# precomputed Heinz modules from pseudo-replicates
## Not run: lib <- file.path(.path.package("BioNet"), "extdata") 
modules <- readHeinzGraph(node.file=file.path(datadir, "ALL_n_resample.txt.0.hnz"), network=network)
cons.scores <- consensusScores(modules, network)

## End(Not run)

Compute the density of the bum distribution

Description

Function to compute the density of the beta-uniform mixture model.

Usage

fbum(x, lambda, a)

Arguments

x

A numeric value.

lambda

Parameter lambda, mixture parameter, proportion of uniform component

a

Parameter a, shape parameter of beta component

Value

Value of the density of the bum distribution for x.

Author(s)

Marcus Dittrich

References

S. Pounds, S.W. Morris (2003) Estimating the occurrence of false positives and false negatives in microarray studies by approximating and partitioning the empirical distribution of p-values. Bioinformatics, 19(10): 1236-1242.

See Also

bumOptim, fitBumModel

Examples

y <- fbum(x=0.5, lambda=0.1, a=0.1)
y

Calculate log likelihood of BUM model

Description

The function calculates the log likelihood of the BUM model.

Usage

fbumLL(parms, x)

Arguments

parms

Vector of parameters; lambda and a.

x

Numerical vector of p-values.

Value

Log likelihood.

Author(s)

Marcus Dittrich

Examples

data(pvaluesExample)
pvals <- pvaluesExample[,1]
bum.mle <- fitBumModel(pvals, plot=FALSE)
fbumLL(parms=c(bum.mle$lambda, bum.mle$a), x=pvals)

Calculate p-value threshold for given FDR

Description

The function calculates the p-value threshold tau for a given false discovery rate. Tau is used for the scoring function.

Usage

fdrThreshold(fdr, fb)

Arguments

fdr

False discovery rate.

fb

Model from the beta-uniform mixture fitting.

Value

P-value threshold tau.

Author(s)

Marcus Dittrich

References

S. Pounds, S.W. Morris (2003) Estimating the occurrence of false positives and false negatives in microarray studies by approximating and partitioning the empirical distribution of p-values. Bioinformatics, 19(10): 1236-1242.

See Also

fbum, fitBumModel

Examples

data(pvaluesExample)
pvals <- pvaluesExample[,1]
bum.mle <- fitBumModel(pvals, plot=FALSE)
tau <- fdrThreshold(fdr=0.001, fb=bum.mle)
tau

Fit beta-uniform mixture model to a p-value distribution

Description

The function fits a beta-uniform mixture model to a given p-value distribution. The BUM method was introduced by Stan Pounds and Steve Morris to model the p-value distribution as a signal-noise decompostion. The signal component is assumed to be B(a,1)-distributed, whereas the noise component is uniform-distributed under the null hypothesis.

Usage

fitBumModel(x, plot = TRUE, starts=10)

Arguments

x

Numeric vector of p-values.

plot

Boolean value, whether to plot a histogram and qqplot of the p-values with the fitted model.

starts

Numeric value giving the number of starts for the optimization.

Value

Maximum likelihood estimator object for the fitted bum model. List of class fb with the following elements:

lambda

Fitted parameter lambda for the beta-uniform mixture model.

a

Fitted parameter a for the beta-uniform mixture model.

negLL

Negative log-likelihood.

pvalues

P-value vector.

Author(s)

Daniela Beisser

References

S. Pounds, S.W. Morris (2003) Estimating the occurrence of false positives and false negatives in microarray studies by approximating and partitioning the empirical distribution of p-values. Bioinformatics, 19(10): 1236-1242.

Examples

data(pvaluesExample)
pvals <- pvaluesExample[,1]
bum.mle <- fitBumModel(pvals, plot=TRUE)
bum.mle

Partition scores for subgraphs of the network

Description

The function partitions the scores into scores for each subgraph of the network.

Usage

getCompScores(network, score)

Arguments

network

A network in graphNEL or igraph format.

score

Vector of scores.

Value

A data frame with the components of the network and the score for each PPI identifier.

Author(s)

Marcus Dittrich

Examples

library(DLBCL)
data(interactome)
data(dataLym)
# create random subgraph with 100 nodes and their direct neighbors
nodes <- nodes(interactome)[sample(length(nodes(interactome)), 100)]
subnet <- subNetwork(nodeList=nodes, network=interactome, neighbors="first")
score <- dataLym$score001
names(score) <- dataLym$label
getCompScores(score=score, network=subnet)

Get representation of graph as edgelist

Description

A network in graphNEL or igraph format is converted to an edgelist.

Usage

getEdgeList(network)

Arguments

network

Network in graphNEL or igraph format.

Value

A matrix whose columns represent the connected edges.

Author(s)

Marcus Dittrich

Examples

library(DLBCL)
data(interactome)
getEdgeList(interactome)[1:10,]

Histogram of the p-value distribution with the fitted bum model

Description

The function plots a histogram of the p-values together with the fitted bum-model.

Usage

## S3 method for class 'bum'
hist(x, breaks=50, main="Histogram of p-values", xlab="P-values", ylab="Density", ...)

Arguments

x

Maximum likelihood estimator object of the beta-uniform mixture fit.

breaks

Breaks for the histogram.

main

An overall title for the plot.

xlab

A title for the x axis.

ylab

A title for the y axis.

...

Other graphic parameters for the plot.

Author(s)

Daniela Beisser

See Also

fitBumModel, hist.bum, bumOptim

Examples

data(pvaluesExample)
pvals <- pvaluesExample[,1]
mle <- fitBumModel(pvals, plot=FALSE)
hist(mle)

Extract largest component of network

Description

The function extracts the largest component of a network.

Usage

largestComp(network)

Arguments

network

A graph in graphNEL or igraph format.

Value

A new graph object that represents the largest component of the given network.

Author(s)

Marcus Dittrich

Examples

library(DLBCL)
data(interactome)
interactome
largestComp(interactome)

Component with largest score

Description

The function extracts the component of the network with the largest score. All nodes have to exceed the given level for the score.

Usage

largestScoreComp(network, score, level=0)

Arguments

network

Network in graphNEL or igraph format.

score

Vector of scores for the network.

level

Cut-off level for the score for the component.

Value

Subgraph of the network with a score larger than the given level.

Author(s)

Marcus Dittrich

Examples

library(DLBCL)
data(interactome)
data(dataLym)
network <- rmSelfLoops(interactome)
score <- dataLym$score001
names(score) <- dataLym$label
lComp <- largestScoreComp(network=network, score=score, level=1)
## Not run: plotModule(lComp)

Load network from Cytoscape sif file

Description

The function loads a network from a Cytoscape sif file. Edge attributes are provided in the ea.file or vector of ea.files. The node attributes are provided the same way. For other formats see read.graph in the igraph package.

Usage

loadNetwork.sif(sif.file, na.file, ea.file, format=c("graphNEL", "igraph"), directed=FALSE)

Arguments

sif.file

Cytoscape sif file, containing the network.

na.file

File or vector of file with Cytoscape node attibutes.

ea.file

File or vector of file with Cytoscape edge attibutes.

format

Format of output graph, either graphNEL or igraph.

directed

Boolean value for directed or undirected graph.

Value

Graph with loaded attributes.

Author(s)

Daniela Beisser

Examples

## Not run: lib <- file.path(.path.package("BioNet"), "extdata") 
# load interaction file, node attribute file with a node weight of 2 for each node and the edge attribute file with a edge weight of 1 for each edge
network <- loadNetwork.sif(sif.file=file.path(lib,"cytoscape.sif"), na.file=file.path(lib,"n.weight.NA"), ea.file=file.path(lib,"weight.EA"), format="graphNEL", directed=FALSE);
network;
nodeData(network);
edgeData(network);

## End(Not run)

Load network from tabular format

Description

The function loads a network from a tabular format.

Usage

loadNetwork.tab(file, header=TRUE, directed=FALSE, format=c("graphNEL", "igraph"))

Arguments

file

File with network to load.

header

Booelan value whether to include header or not.

directed

Booelan value whether the network is to be directed or not.

format

Output format of the network, either graphNEL or igraph

Author(s)

Marcus Dittrich

See Also

loadNetwork.sif


Create graph from source and target vectors

Description

Function to create a graph in graphNEL or igraph format from a source and a target vector.

Usage

makeNetwork(source, target, edgemode="undirected", format=c("graphNEL", "igraph"))

Arguments

source

Vector of source nodes.

target

Vector of corresponding target nodes.

edgemode

For an "undirected" or "directed" network.

format

Graph format, eiter graphNEL or igraph.

Value

A graph object.

Author(s)

Marcus Dittrich

See Also

loadNetwork.sif, saveNetwork

Examples

source <- c("a", "b", "c", "d")
target <- c("b", "c", "a", "a")
graph <- makeNetwork(source, target, edgemode="undirected")

Select probeset by variance and get PPI ID

Description

The function selects for each gene the probeset with the highest variance and gets the PPI ID for each gene. The PPI identifier is: gene symbol(Entrez ID). Affymetrix identifiers are mapped to the ENTREZ ID.

Usage

mapByVar(exprSet, network=NULL, attr="geneID", ignoreAFFX=TRUE)

Arguments

exprSet

Affymetrix ExpressionSet.

network

Network that is used to map the Affymetrix identifiers.

attr

The attribute of the network that is used to map the Affymetrix IDs. The IDs are mapped to the unique Entrez gene IDs, which are by default stored in the "geneID" attribute of the network.

ignoreAFFX

Boolean value, whether to ignore or leave AFFX control genes.

Value

Expression matrix with one gene (PPI ID) per probeset.

Author(s)

Daniela Beisser

Examples

## Not run: library(ALL);
data(ALL);
mapped.e.set <- mapByVar(ALL);
mapped.e.set[1:10,];
## End(Not run)

Permute node labels

Description

Function to permutate node labels of a given network.

Usage

permutateNodes(network)

Arguments

network

Network in graphNEL or igraph format.

Value

Network with permutated labels.

Author(s)

Marcus Dittrich

Examples

library(DLBCL)
data(interactome)
# remove self-loops before permutating the labels
interactome <- rmSelfLoops(interactome)
perm.net <- permutateNodes(interactome)
perm.net

Upper bound pi for the fraction of noise

Description

The function calculates the upper bound pi for the fraction of noise.

Usage

piUpper(fb)

Arguments

fb

Fitted bum model, list with parameters a and lambda.

Value

Numerical value for the upper bound pi.

Author(s)

Marcus Dittrich

See Also

bumOptim, fitBumModel

Examples

data(pvaluesExample)
pvals <- pvaluesExample[,1]
bum <- bumOptim(pvals, starts=10)
piUpper(fb=bum)

Quantile-quantile plot for the beta-uniform mixture model

Description

The function plot the theoretical quantiles of the fitted bum model against the quantiles of the observed p-value distribution.

Usage

## S3 method for class 'bum'
plot(x, main="QQ-Plot", xlab="Estimated p-value", ylab="Observed p-value", ...)

Arguments

x

Maximum likelihood estimation object of the fitted bum model.

main

An overall title for the plot.

xlab

A title for the x axis.

ylab

A title for the y axis.

...

Other graphic parameters for the plot.

Author(s)

Daniela Beisser

See Also

fitBumModel, plot.bum, bumOptim

Examples

data(pvaluesExample)
pvals <- pvaluesExample[,1]
mle <- fitBumModel(pvals, plot=FALSE)
plot(mle)

3D plot of the network

Description

The function plots a network from graphNEL or igraph format in 3D using a modified function from the package igraph and requires the package rgl which uses openGL. The 3D plot can be zoomed, rotated, shifted on the canvas. This function is just used to visualize the modules. For further plotting options use the rglplot function of the igraph package. If a score attribute is provided in the graph this will be used for the coloring of the nodes. Otherwise a vector of values can be given by the diff.or.score argument. The vector has to contain positive and negative values, either scores or values for differential expression (fold changes). Labels for the nodes can be provided by the labels argument, otherwise it will be automatically looked for a geneSymbol attribute of the nodes.

Usage

plot3dModule(network, labels=NULL, windowSize = c(100,100,1500,1000), diff.or.scores=NULL, red=c("negative", "positive"), ...)

Arguments

network

Network in graphNEL or igraph format.

labels

Labels for the nodes of the network. Otherwise it will be automatically looked for a geneSymbol attribute of the nodes.

windowSize

Numerical vector of size four to set the size of the rgl device.

diff.or.scores

Named numerical vector of differential expression (fold changes) or scores of the nodes in the network. These will be used for node coloring. Otherwise a score attribute of the nodes will be automatically used.

red

Either "negative" or "positive", to specify which values are to be colored red in the plot.

...

Other graphic parameters for the plot.

Author(s)

Daniela Beisser

See Also

save3dModule, plotModule

Examples

library(DLBCL)
data(interactome)
data(dataLym)
interactome <- subNetwork(dataLym$label, interactome)
interactome <- rmSelfLoops(interactome)
fchange <- dataLym$diff
names(fchange) <- dataLym$label
subnet <- largestComp(subNetwork(nodes(interactome)[1:100], interactome))
diff <- fchange[nodes(subnet)]

## Not run: library(rgl);
plot3dModule(network=subnet, diff.or.score=diff)
## End(Not run)

Log likelihood surface plot

Description

The function plots the log likelihood surface for all a and lambda parameter of the beta-uniform mixture model.

Usage

plotLLSurface(x, opt=NULL, main="Log-Likelihood Surface", color.palette = heat.colors, nlevels = 32)

Arguments

x

Numeric vector of p-values.

opt

List of optimal parameters for a and lambda from the beta-uniform mixture model.

main

The overall title of the plot.

color.palette

Color scheme of the image plot.

nlevels

Number of color levels.

Author(s)

Marcus Dittrich

Examples

library(DLBCL)
data(dataLym)
pvals <- dataLym$t.pval
names(pvals) <- dataLym$label
mle <- fitBumModel(pvals, plot=FALSE)
plotLLSurface(x=pvals, opt=mle)

Plot of the network

Description

The function plots a network from graphNEL or igraph format, adapted from an igraph plotting function. It is just used to visualize the modules. For further plotting options use the plot.igraph function of the igraph package. The shapes of the nodes can be changed according to the scores argument, then negative scores appear squared. The color of the nodes can be changed according to the diff.expr argument. Negative values lead to green nodes, positive values are colored in red. If the vectors are not provided, it will be automatically looked for nodes attributes with the name score and diff.expr.

Usage

plotModule(network, layout=layout.fruchterman.reingold, labels=NULL, diff.expr=NULL, scores=NULL, main=NULL, vertex.size=NULL, ...)

Arguments

network

Network in graphNEL or igraph format.

layout

Layout algorithm, e.g. layout.fruchterman.reingold or layout.kamada.kawai.

labels

Labels for the nodes of the network.

diff.expr

Named numerical vector of differential expression (fold changes) of the nodes in the network. These will be used for coloring of the nodes. It will be automatically looked for nodes attribute with the name diff.expr, if the argument is null.

scores

Named numerical vector of scores of the nodes in the network. These will be used for the shape of the nodes. It will be automatically looked for nodes attribute with the name score, if the argument is null.

main

Main title of the plot.

vertex.size

Numerical value or verctor for the size of the vertices.

...

Other graphic parameters for the plot.

Author(s)

Marcus Dittrich and Daniela Beisser

See Also

plot3dModule

Examples

library(DLBCL)
data(dataLym)
data(interactome)
interactome <- subNetwork(dataLym$label, interactome)
interactome <- rmSelfLoops(interactome)
fchange <- dataLym$diff
names(fchange) <- dataLym$label
# create random subnetwork
subnet <- largestComp(subNetwork(nodes(interactome)[1:100], interactome))
fchange <- fchange[nodes(subnet)]

# color random subnetwork by the fold change
## Not run: plotModule(network=subnet, diff.expr=fchange)

Print information about bum model

Description

The function prints information about the bum model.

Usage

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

Arguments

x

Maximum likelihood estimator object of the beta-uniform mixture fit.

...

Other graphic parameters for print.

Author(s)

Marcus Dittrich

See Also

fitBumModel, summary.bum

Examples

data(pvaluesExample)
pvals <- pvaluesExample[,1]
mle <- fitBumModel(pvals, plot=FALSE)
print(mle)

Example p-values for aggregation statistics

Description

Data example consisting of a matrix of p-values. Each gene has two corresponding p-values. These p-values can be aggregated into a p-value of p-values by the method aggrPvals.

Usage

data(pvaluesExample)

Examples

data(pvaluesExample)
pvaluesExample[1:10,]

Convert HEINZ output to graph

Description

Function to convert the HEINZ output to a graph object, or if the output is in matrix form, it will create a list of graphs. The function needs the node and the original network, from which the module is calculated.

Usage

readHeinzGraph(node.file, network, format=c("graphNEL", "igraph"))

Arguments

node.file

Heinz node output file.

network

Original network from which Heinz input was created.

format

Graph format of output, either igraph or graphNEL.

Value

Graph object.

Author(s)

Daniela Beisser

Examples

library(DLBCL)
data(interactome)
# precomputed Heinz output files
## Not run: lib <- file.path(path.package("BioNet"), "extdata") 
module <- readHeinzGraph(node.file=file.path(lib, "lymphoma_nodes_001.txt.0.hnz"), network=interactome, format="graphNEL");
plotModule(module);

## End(Not run)

Convert HEINZ output to tree

Description

Converts the HEINZ output to a tree in graph format. If the output is in matrix form, it will create a list of graphs. The function needs the node and edge file and the original network from which the module is calculated.

Usage

readHeinzTree(node.file, edge.file, network, format=c("graphNEL", "igraph"))

Arguments

node.file

Heinz node output file.

edge.file

Heinz edge output file.

network

Original network from which Heinz input was created.

format

Output format of the graph, either igraph or graphNEL.

Value

A graph object.

Author(s)

Daniela Beisser

Examples

library(DLBCL)
data(interactome)
# precomputed Heinz output files
## Not run: lib <- file.path(.path.package("BioNet"), "extdata") 
module <- readHeinzTree(node.file=file.path(lib, "lymphoma_nodes_001.txt.0.hnz"), edge.file=file.path(lib, "lymphoma_edges_001.txt.0.hnz"), network=interactome, format="graphNEL");
plotModule(module);

## End(Not run)

Resampling of microarray expression values and test for differential expression.

Description

The function uses a 50% jackknife resampling to calculate a pseudo-replicate of the expression matrix. The resampled expression values are used thereupon to calculate p-values for the differential expression between the given groups. Only two-group comparisons are allowed for the perfomed t-test.

Usage

resamplingPvalues(exprMat, groups, alternative = c("two.sided", "less", "greater"), resampleMat=FALSE)

Arguments

exprMat

Matrix with microarray expression values.

groups

Factors for two groups that are tested for differential expression.

alternative

Testing alternatives for the t-test: "two.sided", "less" or "greater".

resampleMat

Boolean value, whether to retrieve the matrix of jacknife resamples or not.

Value

A result list is returned, consisting of:

p.values

VNumerical vector of p-values.

resampleMat

Matrix of resampled expression values.

Author(s)

Daniela Beisser

Examples

library(ALL)
data(ALL)
mat <- exprs(ALL)
groups <- factor(c(rep("A", 64), rep("B", 64)))
results <- resamplingPvalues(mat, groups, alternative="greater")

Remove self-loops in a graph

Description

The function removes self-loops, edges that start and end in the same node, from the network.

Usage

rmSelfLoops(network)

Arguments

network

A graph object, either in graphNEL or igraph format.

Value

The graph with the removed edges.

Author(s)

Marcus Dittrich

Examples

graph <- makeNetwork(c("a","b","c","d","e","a"), c("b","c","d","e","e","e"))
graph2 <- rmSelfLoops(graph)
edges(graph)
edges(graph2)

Calculate heuristically maximum scoring subnetwork

Description

The function uses an heuristic approach to calculate the maximum scoring subnetwork. Based on the given network and scores the positive nodes are in the first step aggregated to meta-nodes between which minimum spanning trees are calculated. In regard to this, shortest paths yield the approximated maximum scoring subnetwork. This function can be used if a CPLEX license is not available to calculate the optimal solution.

Usage

runFastHeinz(network, scores)

Arguments

network

A graph in igraph or graphNEL format.

scores

A named vector, containing the scores for the nodes of the network. All nodes need to be scored in order to run the algorithm.

Value

A subnetwork in the input network format.

Author(s)

Daniela Beisser

See Also

writeHeinzEdges, writeHeinzNodes, readHeinzTree, readHeinzGraph, runHeinz

Examples

library(DLBCL)
# load p-values
data(dataLym)
# load graph
data(interactome)
# get induced subnetwork for all genes contained on the chip
interactome <- subNetwork(dataLym$label, interactome)
p.values <- dataLym$t.pval
names(p.values) <- dataLym$label
bum <- fitBumModel(p.values, plot=TRUE)
scores <- scoreNodes(network=interactome, fb=bum, fdr=0.0001)
module <- runFastHeinz(network=interactome, scores=scores)
## Not run: plotModule(module)

Start HEINZ

Description

The function starts HEINZ from command line. The HEINZ folder has to include the heinz.py python script and the dhea file. CPLEX has to be installed and accessible from the computer R runs on.

Usage

runHeinz(heinz.folder="", heinz.e.file, heinz.n.file, N=TRUE, E=FALSE, diff=-1, n=1)

Arguments

heinz.folder

The folder which contains the heinz.py python script and the dhea file.

heinz.e.file

The HEINZ edge input file. See writeHeinzEdges

heinz.n.file

The HEINZ node input file. See writeHeinzNodes

N

Boolean value, whether to run HEINZ on nodes.

E

Boolean value, whether to run HEINZ on edges. HEINZ can run on both with N and E set to TRUE.

diff

Difference of suboptimal solutions to optimal solution in haming distance in percent. Parameter is set to -1 for optimal solution.

n

Number of optimal and suboptimal solutions, the standard n=1 delivers only the optimal solution.

Details

This function starts the integer linear programming algorithm to calculate the optimal scoring subnetwork. The algorithm might be started in the command line when the CPLEX is installed on another machine. To start it from command line use: heinz.py -e edge.file.txt -n node.file.txt -E False/True -N False/True. The results can be loaded with readHeinzTree, readHeinzGraph as a graph object.

Author(s)

Daniela Beisser

References

M. T. Dittrich, G. W. Klau, A. Rosenwald, T. Dandekar, T. Mueller (2008) Identifying functional modules in protein-protein interaction networks: an integrated exact approach. (ISMB2008) Bioinformatics, 24: 13. i223-i231 Jul.

See Also

writeHeinzEdges, writeHeinzNodes, readHeinzTree, readHeinzGraph


Save a 3D plot of the network

Description

The function saves a 3D plot of a network to file, therefore it requires the plot to be open. A screenshot of the 3D plot can be saved in "pdf" format. Background of the device is changed to white for plotting. The screenshot can take several seconds for large plots.

Usage

save3dModule(file)

Arguments

file

File to save to.

Author(s)

Daniela Beisser

See Also

plot3dModule, plotModule

Examples

library(DLBCL)
data(dataLym)
data(interactome)
interactome <- subNetwork(dataLym$label, interactome)
fchange <- dataLym$diff
names(fchange) <- dataLym$label
subnet <- largestComp(subNetwork(nodes(interactome)[1:100], interactome))
diff <- fchange[nodes(subnet)]

## Not run: library(rgl);
plot3dModule(network=subnet, diff.or.score=diff);
save3dModule(file="test")
## End(Not run)

Save undirected network in various formats

Description

The function saves a graph in a Cytoscape readable format: either in XGMML format, or as two tables, one for the nodes with attributes and one for the edges with attributes, or as .sif file. Or other standard formats like tab separated, .tgf, .net

Usage

saveNetwork(network, name="network", file, type=c("table", "XGMML", "sif", "tab", "tgf", "net"))

Arguments

network

Network to save.

name

Name of the network, only needed for the XGMML format.

file

File to save to.

type

Type in which graph shall be saved.

Details

The format types are "XGMML", "table", "sif", "tab", "tgf" and "net". XGMML (eXtensible Graph Markup and Modeling Language) is an XML format based on GML which is used for graph description. Edges, nodes and their affiliated attributes are all saved in one file. In the table format two tables are created, one for the nodes with attributes and one for the edges with attributes. The sif format creates a .sif file for the network and an node attribute (.NA) or edge attribute (.EA) for each attribute. The name of the attribute is the filename. Tab writes only the edges of the network in a tabular format. Tgf save the network to simple .tgf format. The net format writes a Pajek readable file of the network and the ET type saves the edge tags to file.

Author(s)

Daniela Beisser and Marcus Dittrich

Examples

library(DLBCL)
#create small network
library(igraph)
data(interactome) 
interactome <- igraph.from.graphNEL(interactome)
small.net <- subNetwork(V(interactome)[1:16]$name, interactome)
E(small.net)$e.weight <- rep(1,length(E(small.net)))
V(small.net)$n.weight <- rep(2,length(V(small.net)))
summary(small.net)
## Not run: saveNetwork(small.net, file="example_network", name="small.net", type="XGMML")

Dataframe of scores over a given range of FDRs

Description

The function generates a dataframe for a given range of FDRs.

Usage

scanFDR(fb, fdr, labels=names(fb$pvalues))

Arguments

fb

Fitted bum model.

fdr

Vector of FDRs.

labels

Data frame labels.

Value

Dataframe of scores for given p-values and a range of FDRs.

Author(s)

Marcus Dittrich

See Also

bumOptim, fitBumModel

Examples

data(pvaluesExample)
pvals <- pvaluesExample[,1]
bum <- bumOptim(pvals, starts=10)
scores <- scanFDR(fb=bum, fdr=c(0.1, 0.001, 0.0001))
scores[1:10,]

Scoring function for p-values

Description

The function calculates a score for each gene with a given FDR from the fitted beta-uniform mixture model.

Usage

scoreFunction(fb, fdr=0.01)

Arguments

fb

Model from the beta-uniform mixture fitting.

fdr

Numeric constant, from the false discovery rate a p-value threshold is calculated. P-values below this threshold are considered to be significant and will score positively, p-values a bove the threshold are supposed to arise from the null model. The FDR can be used to control the size of the maximum scoring subnetwork, by zooming in and out in the same region.

Value

Score vector for the given p-values.

Author(s)

Marcus Dittrich and Daniela Beisser

References

For details on the score calculation see: M. T. Dittrich, G. W. Klau, A. Rosenwald, T. Dandekar, T. Mueller (2008) Identifying functional modules in protein-protein interaction networks: an integrated exact approach. (ISMB2008) Bioinformatics, 24: 13. i223-i231 Jul.

Examples

data(pvaluesExample)
pvals <- pvaluesExample[,1]
bum.mle <- fitBumModel(pvals, plot=FALSE)
scores <- scoreFunction(fdr=0.1, fb=bum.mle)
scores

Score the nodes of a network

Description

The function derives scores from the p-values of the nodes of a network.

Usage

scoreNodes(network, fb, fdr=0.05)

Arguments

network

A network in graphNEL or igraph format.

fb

Fitted bum model.

fdr

False discovery rate.

Value

Ordered score vector for the nodes of the network.

Author(s)

Marcus Dittrich

See Also

bumOptim, fitBumModel

Examples

library(DLBCL)
# load p-values
data(dataLym)
# load graph
data(interactome)
# get induced subnetwork for all genes contained on the chip
chipGraph <- subNetwork(dataLym$label, interactome)
p.values <- dataLym$t.pval
names(p.values) <- dataLym$label
bum <- fitBumModel(p.values, plot=TRUE)
scoreNodes(network=chipGraph, fb=bum, fdr=0.001)

Change score offset for 2 FDRs

Description

Function to change score offset from FDR1 to FDR2.

Usage

scoreOffset(fb, fdr1, fdr2)

Arguments

fb

Model from the beta-uniform mixture fitting.

fdr1

First false discovery rate.

fdr2

Second false discovery rate.

Value

Offset for the score of the second FDR.

Author(s)

Marcus Dittrich

See Also

bumOptim, fitBumModel

Examples

data(pvaluesExample)
pvals <- pvaluesExample[,1]
bum <- bumOptim(pvals, starts=10)
scoreOffset(bum, fdr1=0.001, fdr2=0.000001)

Get a sorted edgelist

Description

Function to get a sorted edgelist where the source protein is alphabetically smaller than the target protein from an undirected network.

Usage

sortedEdgeList(network)

Arguments

network

Undirected network in igraph or graphNEL format.

Value

Vector of sorted edges, where the source protein is alphabetically smaller than the target protein.

Author(s)

Daniela Beisser

Examples

library(DLBCL)
data(interactome)
E.list <- sortedEdgeList(interactome)

Create a subGraph

Description

The function creates a subgraph with the nodes given in the nodeList or for these nodes including their direct neighbors.

Usage

subNetwork(nodeList, network, neighbors=c("none", "first"))

Arguments

nodeList

Character vector of nodes, contained in the subgraph.

network

Graph that is used for subgraph extraction.

neighbors

Neighborhood, that is chosen for the subgraph extraction. "none" are only the selected nodes, "first" includes the direct neighbors of the selected nodes.

Value

A graph object.

Author(s)

Marcus Dittrich

Examples

library(igraph)
el <- cbind(c("a", "b", "c", "d", "e", "f", "d"), c("b", "c", "d", "e", "f", "a", "b"))
graph <- graph.edgelist(el, directed=TRUE)

node.list <- c("a", "b", "c")
graph2 <- subNetwork(nodeList=node.list, network=graph)
## Not run: par(mfrow=c(1,2));
plotModule(graph);
plotModule(graph2)
## End(Not run)

# or in graphNEL format: 
graph3 <- igraph.to.graphNEL(graph)
graph4 <- subNetwork(nodeList=node.list, network=graph3)
graph3
graph4

Print summary of informations about bum model

Description

The function summarizes information about the bum model.

Usage

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

Arguments

object

Maximum likelihood estimator object of the beta-uniform mixture fit.

...

Other graphic parameters for summary.

Author(s)

Daniela Beisser

See Also

fitBumModel, print.bum

Examples

data(pvaluesExample)
pvals <- pvaluesExample[,1]
mle <- fitBumModel(pvals, plot=FALSE)
summary(mle)

Write input files for HEINZ

Description

Function to write the input files with the node and edge scores for HEINZ. These files are used to calculate the maximum scoring subnetwork of the graph. The node scores are matched by their names to the nodes of the network, therefore if nodes.scores are provided as a vector or matrix, the vector has to be named, respectively the matrix has to be provided with rownames. If the network contains more nodes than the score vector, the nodes without a score are scored with the average over all nodes. If the nodes should not be scored and used for the calculation of the maximum scoring subnetwork, draw a subnetwork (subNetwork) first and use this for the argument network. The edge scores can be provided as a vector or matrix as the edge.scores argument. If no scores are provided in the arguments, but the use.node.scores or use.edge.scores argument is set to TRUE, it will be automatically looked for the "score" attribute of the nodes and edges of the network.

Usage

writeHeinz(network, file, node.scores=0, edge.scores=0, use.node.score=FALSE, use.edge.score=FALSE)

Arguments

network

Network from which to calculate the maximum scoring subnetwork.

file

File to write to.

node.scores

Numeric vector or matrix of scores for the nodes of the network. Names of the vector or rownames of the matrix have to correspond to the PPI identifiers of the network. The scores can also be used from the node attribute "score", given one score for each node.

edge.scores

Numeric vector of scores for the edges of the network. Edge scores have to be given in the order of the edges in the network. It is better to append the edge scores as the edge attribute "score" to the network: V(network)\$score and set use.scores to TRUE.

use.node.score

Boolean value, whether to use the node attribute "score" in the network as node scores.

use.edge.score

Boolean value, whether to use the edge attribute "score" in the network as edge scores.

Author(s)

Daniela Beisser

See Also

writeHeinzNodes and writeHeinzEdges

Examples

library(DLBCL)
# use Lymphoma data and graph to find module
data(interactome)
data(dataLym)
# get induced subnetwork for all genes contained on the chip
chipGraph <- subNetwork(dataLym$label, interactome)
score <- dataLym$score001
names(score) <- dataLym$label
## Not run: writeHeinz(network=chipGraph, file="lymphoma_001", node.scores=score, edge.scores=0)

Write edge input file for HEINZ

Description

Function to write an input file for HEINZ with edge scores. If no edge scores are used, they are set to 0. In order to run HEINZ, a node input and edge input file are needed.

Usage

writeHeinzEdges(network, file, edge.scores=0, use.score=FALSE)

Arguments

network

Network from which to calculate the maximum scoring subnetwork.

file

File to write to.

edge.scores

Numeric vector of scores for the edges of the network. Edge scores have to be given in the order of the edges in the network. It is better to append the edge scores as the edge attribute "score" to the network: V(network)\$score and set use.score to TRUE.

use.score

Boolean value, whether to use the edge attribute "score" in the network as edge scores.

Author(s)

Daniela Beisser

See Also

writeHeinzNodes and writeHeinz

Examples

library(DLBCL)
# use Lymphoma data and graph to find module
data(interactome)
data(dataLym)
# get induced subnetwork for all genes contained on the chip
chipGraph <- subNetwork(dataLym$label, interactome)
# remove self loops
graph <- rmSelfLoops(chipGraph)
## Not run: writeHeinzEdges(network=graph, file="lymphoma_edges_001", use.score=FALSE)
score <- dataLym$score001
names(score) <- dataLym$label
## Not run: writeHeinzNodes(network=graph, file="lymphoma_nodes_001", node.scores=score)


# write another edge file with edge scores 
library(igraph)
data(interactome)
interactome <- igraph.from.graphNEL(interactome)
small.net <- subNetwork(V(interactome)[1:16]$name, interactome)
scores <- c(1:length(E(small.net)))
E(small.net)$score <- scores
## Not run: writeHeinzEdges(network=small.net, file="test_edges", use.score=TRUE)

Write node input file for HEINZ

Description

Function to write an input file with the node scores for HEINZ. This file is used together with the edge input file to calculate the maximum scoring subnetwork of the graph. The scores are matched by their names to the nodes of the network, therefore if nodes.scores are provided as a vector or matrix, the vector has to be named, respectively the matrix has to be provided with rownames. If the network contains more nodes than the score vector, the nodes without a score are scored with the average over all nodes. If the nodes should not be scored and used for the calculation of the maximum scoring subnetwork, draw a subnetwork subNetwork first and use this for the argument network.

Usage

writeHeinzNodes(network, file, node.scores=0, use.score=FALSE)

Arguments

network

Network from which to calculate the maximum scoring subnetwork.

file

File to write to.

node.scores

Numeric vector or matrix of scores for the nodes of the network. Names of the vector or rownames of the matrix have to correspond to the PPI identifiers of the network. The scores can also be used from the node attribute "score", given one score for each node.

use.score

Boolean value, whether to use the node attribute "score" in the network as node scores.

Details

Use scoreNodes or scoreFunctionto derive scores from a vector of p-values.

Author(s)

Daniela Beisser

See Also

writeHeinzEdges and writeHeinz

Examples

#create small network
library(DLBCL)
data(interactome)
small.net <- subNetwork(nodes(interactome)[0:15], interactome)
scores <- c(1:length(nodes(small.net)))
names(scores) <- nodes(small.net)
## Not run: writeHeinzNodes(network=small.net, file="test_nodes", node.scores=scores)

# use Lymphoma data and graph to find module
library(DLBCL)
data(interactome)
data(dataLym)
# get induced subnetwork for all genes contained on the chip
chipGraph <- subNetwork(dataLym$label, interactome)
## Not run: writeHeinzEdges(network=chipGraph, file="lymphoma_edges_001", use.score=FALSE)
score <- dataLym$score001
names(score) <- dataLym$label
## Not run: writeHeinzNodes(network=chipGraph, file="lymphoma_nodes_001", node.scores=score)