blockwiseConsensusModules: Find consensus modules across several datasets.

Description

Perform network construction and consensus module detection across several datasets.

Usage

blockwiseConsensusModules(
  multiExpr, blocks = NULL,
  maxBlockSize = 5000,
  randomSeed = 12345,
  corType = "pearson",
  power = 6,
  consensusQuantile = 0,
  networkType = "unsigned",
  TOMType = "unsigned",
  TOMDenom = "min",
  scaleTOMs = TRUE, scaleQuantile = 0.95,
  sampleForScaling = TRUE, sampleForScalingFactor = 1000,
  useDiskCache = TRUE, chunkSize = NULL,
  cacheBase = ".blockConsModsCache",
  deepSplit = 2,
  detectCutHeight = 0.995, minModuleSize = 20,
  checkMinModuleSize = TRUE,
  maxCoreScatter = NULL, minGap = NULL,
  maxAbsCoreScatter = NULL, minAbsGap = NULL,
  pamStage = TRUE, pamRespectsDendro = TRUE,
  minKMEtoJoin =0.7,
  minCoreKME = 0.5, minCoreKMESize = minModuleSize/3,
  minKMEtoStay = 0.2,
  reassignThresholdPS = 1e-4,
  mergeCutHeight = 0.15,
  impute = TRUE,
  getTOMs = NULL,
  saveTOMs = FALSE, 
  saveTOMFileBase = "consensusTOM",
  getTOMScalingSamples = FALSE,
  trapErrors = FALSE,
  checkPower = TRUE,
  numericLabels = FALSE,
  checkMissingData = TRUE,
  maxPOutliers = 1,
  quickCor = 0,
  pearsonFallback = "individual",
  cosineCorrelation = FALSE,
  nThreads = 0,
  verbose = 2, indent = 0)

Arguments

multiExpr

expression data in the multi-set format (see checkSets). A vector of lists, one per set. Each set must contain a component data that contains the expression data, with rows corresponding to

blocks

optional specification of blocks in which hierarchical clustering and module detection should be performed. If given, must be a numeric vector with one entry per gene of multiExpr giving the number of the block to which the corresponding ge

maxBlockSize

integer giving maximum block size for module detection. Ignored if blocks above is non-NULL. Otherwise, if the number of genes in datExpr exceeds maxBlockSize, genes will be pre-clustered into blocks whose size sho

randomSeed

integer to be used as seed for the random number generator before the function starts. If a current seed exists, it is saved and restored upon exit. If NULL is given, the function will not save and restore the seed.

corType

character string specifying the correlation to be used. Allowed values are (unique abbreviations of) "pearson" and "bicor", corresponding to Pearson and bidweight midcorrelation, respectively. Missing values are handled using t

power

soft-thresholding power for netwoek construction.

consensusQuantile

qunatile at which consensus is to be defined. See details.

networkType

network type. Allowed values are (unique abbreviations of) "unsigned", "signed", "signed hybrid". See adjacency.

TOMType

one of "none", "unsigned", "signed". If "none", adjacency will be used for clustering. If "unsigned", the standard TOM will be used (more generally, TOM function will receive the adjacency

TOMDenom

a character string specifying the TOM variant to be used. Recognized values are "min" giving the standard TOM described in Zhang and Horvath (2005), and "mean" in which the min function in the denominator is repl

scaleTOMs

should set-specific TOM matrices be scaled to the same scale?

scaleQuantile

if scaleTOMs is TRUE, topological overlaps (or adjacencies if TOMs are not computed) will be scaled such that their scaleQuantile quantiles will agree.

sampleForScaling

if TRUE, scale quantiles will be determined from a sample of network similarities. Note that using all data can double the memory footprint of the function and the function may fail.

sampleForScalingFactor

determines the number of samples for scaling: the number is 1/scaleQuantile * sampleForScalingFactor. Should be set well above 1 to ensure accuracy of the sampled quantile.

useDiskCache

should calculated network similarities in individual sets be temporarilly saved to disk? Saving to disk is somewhat slower than keeping all data in memory, but for large blocks and/or many sets the memory footprint may be too big.

chunkSize

network similarities are saved in smaller chunks of size chunkSize.

cacheBase

character string containing the desired name for the cache files. The actual file names will consists of cacheBase and a suffix to make the file names unique.

deepSplit

integer value between 0 and 4. Provides a simplified control over how sensitive module detection should be to module splitting, with 0 least and 4 most sensitive. See cutreeDynamic for

detectCutHeight

dendrogram cut height for module detection. See cutreeDynamic for more details.

minModuleSize

minimum module size for module detection. See cutreeDynamic for more details.

checkMinModuleSize

logical: should sanity checks be performed on minModuleSize?

maxCoreScatter

maximum scatter of the core for a branch to be a cluster, given as the fraction of cutHeight relative to the 5th percentile of joining heights. See cutreeDynamic for more

minGap

minimum cluster gap given as the fraction of the difference between cutHeight and the 5th percentile of joining heights. See cutreeDynamic for more details.

maxAbsCoreScatter

maximum scatter of the core for a branch to be a cluster given as absolute heights. If given, overrides maxCoreScatter. See cutreeDynamic for more details.

minAbsGap

minimum cluster gap given as absolute height difference. If given, overrides minGap. See cutreeDynamic for more details.

pamStage

logical. If TRUE, the second (PAM-like) stage of module detection will be performed. See cutreeDynamic for more details.

pamRespectsDendro

Logical, only used when pamStage is TRUE. If TRUE, the PAM stage will respect the dendrogram in the sense an object can be PAM-assigned only to clusters that lie below it on the branch that the object is merged in

minKMEtoJoin

a number between 0 and 1. Genes with eigengene connectivity higher than minKMEtoJoin are automatically assigned to their closest module.

minCoreKME

a number between 0 and 1. If a detected module does not have at least minModuleKMESize genes with eigengene connectivity at least minCoreKME, the module is disbanded (its genes are unlabeled and returned to the pool of genes wa

minCoreKMESize

see minCoreKME above.

minKMEtoStay

genes whose eigengene connectivity to their module eigengene is lower than minKMEtoStay are removed from the module.

reassignThresholdPS

per-set p-value ratio threshold for reassigning genes between modules. See Details.

mergeCutHeight

dendrogram cut height for module merging.

impute

logical: should imputation be used for module eigengene calculation? See moduleEigengenes for more details.

getTOMs

deprecated, please use saveTOMs below.

saveTOMs

logical: should the consensus topological overlap matrices for each block be saved and returned?

saveTOMFileBase

character string containing the file name base for files containing the consensus topological overlaps. The full file names have "block.1.RData", "block.2.RData" etc. appended. These files are standard R data files and can be l

getTOMScalingSamples

logical: should samples used for TOM scaling be saved for future analysis? This option is only available when sampleForScaling is TRUE.

trapErrors

logical: should errors in calculations be trapped?

checkPower

logical: should basic sanity check be performed on the supplied power? If you would like to experiment with unusual powers, set the argument to FALSE and proceed with caution.

numericLabels

logical: should the returned modules be labeled by colors (FALSE), or by numbers (TRUE)?

checkMissingData

logical: should data be checked for excessive numbers of missing entries in genes and samples, and for genes with zero variance? See details.

maxPOutliers

only used for corType=="bicor". Specifies the maximum percentile of data that can be considered outliers on either side of the median separately. For each side of the median, if higher percentile than maxPOutliers is conside

quickCor

real number between 0 and 1 that controls the handling of missing data in the calculation of correlations. See details.

pearsonFallback

Specifies whether the bicor calculation, if used, should revert to Pearson when median absolute deviation (mad) is zero. Recongnized values are (abbreviations of) "none", "individual", "all". If set to "none", zero mad will re

cosineCorrelation

logical: should the cosine version of the correlation calculation be used? The cosine calculation differs from the standard one in that it does not subtract the mean.

nThreads

non-negative integer specifying the number of parallel threads to be used by certain parts of correlation calculations. This option only has an effect on systems on which a POSIX thread library is available (which currently includes Linux and Mac OSX, b

verbose

integer level of verbosity. Zero means silent, higher values make the output progressively more and more verbose.

indent

indentation for diagnostic messages. Zero means no indentation, each unit adds two spaces.

Value

A list with the following components:
colorsmodule assignment of all input genes. A vector containing either character strings with module colors (if input numericLabels was unset) or numeric module labels (if numericLabels was set to TRUE). The color "grey" and the numeric label 0 are reserved for unassigned genes.
unmergedColorsmodule colors or numeric labels before the module merging step.
multiMEsmodule eigengenes corresponding to the modules returned in colors, in multi-set format. A vector of lists, one per set, containing eigengenes, proportion of variance explained and other information. See multiSetMEs for a detailed description.
goodSamplesa list, with one component per input set. Each component is a logical vector with one entry per sample from the corresponding set. The entry indicates whether the sample in the set passed basic quality control criteria.
goodGenesa logical vector with one entry per input gene indicating whether the gene passed basic quality control criteria in all sets.
dendrogramsa list with one component for each block of genes. Each component is the hierarchical clustering dendrogram obtained by clustering the consensus gene dissimilarity in the corresponding block.
TOMFilesif saveTOMs==TRUE, a vector of character strings, one string per block, giving the file names of files (relative to current directory) in which blockwise topological overlaps were saved.
blockGenesa list with one component for each block of genes. Each component is a vector giving the indices (relative to the input multiExpr) of genes in the corresponding block.
blocksif input blocks was given, its copy; otherwise a vector of length equal number of genes giving the block label for each gene. Note that block labels are not necessarilly sorted in the order in which the blocks were processed (since we do not require this for the input blocks). See blockOrder below.
blockOrdera vector giving the order in which blocks were processed and in which blockGenes above is returned. For example, blockOrder[1] contains the label of the first-processed block.
originCountif the input consensusQuantile==0, this vector will contain counts of how many times each set contributed the consensus gene similarity value. If the counts are highly unbalanced, the consensus may be biased.
TOMScalingSamplesif the input getTOMScalingSamples is TRUE, this component is a list with one component per block. Each component is again a list with two components: sampleIndex contains indices of the distance structure in which TOM is stored that were sampled, and TOMSamples is a matrix whose rows correspond to TOM samples and columns to individual set. Hence, TOMScalingSamples[[blockNo]]$TOMSamples[index, setNo] contains the TOM entry that corresponds to element TOMScalingSamples[[blockNo]]$sampleIndex[index] of the TOM distance structure in block blockNo and set setNo. (For details on the distance structure, see dist.)

Details

The function starts by optionally filtering out samples that have too many missing entries and genes that have either too many missing entries or zero variance in at least one set. Genes that are filtered out are left unassigned by the module detection. Returned eigengenes will contain NA in entries corresponding to filtered-out samples. If blocks is not given and the number of genes exceeds maxBlockSize, genes are pre-clustered into blocks using the function consensusProjectiveKMeans; otherwise all genes are treated in a single block. For each block of genes, the network is constructed and (if requested) topological overlap is calculated in each set. To minimize memory usage, calculated topological overlaps are optionally saved to disk in chunks until they are needed again for the calculation of the consensus network topological overlap. If requested, the consensus topological overlaps are saved to disk for later use. Genes are then clustered using average linkage hierarchical clustering and modules are identified in the resulting dendrogram by the Dynamic Hybrid tree cut. Found modules are trimmed of genes whose correlation with module eigengene (KME) is less than minKMEtoStay in any of the sets. Modules in which fewer than minCoreKMESize genes have KME higher than minCoreKME (in all sets) are disbanded, i.e., their constituent genes are pronounced unassigned. Conversely, any unassigned genes with KME higher than minKMEtoJoin in all sets are automatically assigned to their nearest module. After all blocks have been processed, the function checks whether there are genes whose KME in the module they assigned is lower than KME to another module. If p-values of the higher correlations are smaller than those of the native module by the factor reassignThresholdPS (in every set), the gene is re-assigned to the closer module. In the last step, modules whose eigengenes are highly correlated are merged. This is achieved by clustering module eigengenes using the dissimilarity given by one minus their correlation, cutting the dendrogram at the height mergeCutHeight and merging all modules on each branch. The process is iterated until no modules are merged. See mergeCloseModules for more details on module merging. The argument quick specifies the precision of handling of missing data in the correlation calculations. Zero will cause all calculations to be executed precisely, which may be significantly slower than calculations without missing data. Progressively higher values will speed up the calculations but introduce progressively larger errors. Without missing data, all column means and variances can be pre-calculated before the covariances are calculated. When missing data are present, exact calculations require the column means and variances to be calculated for each covariance. The approximate calculation uses the pre-calculated mean and variance and simply ignores missing data in the covariance calculation. If the number of missing data is high, the pre-calculated means and variances may be very different from the actual ones, thus potentially introducing large errors. The quick value times the number of rows specifies the maximum difference in the number of missing entries for mean and variance calculations on the one hand and covariance on the other hand that will be tolerated before a recalculation is triggered. The hope is that if only a few missing data are treated approximately, the error introduced will be small but the potential speedup can be significant.

References

Langfelder P, Horvath S (2007) Eigengene networks for studying the relationships between co-expression modules. BMC Systems Biology 2007, 1:54