segChrom {tilingArray}R Documentation

Fit a piecewise constant curve to along chromosome data

Description

This function calls the segment function for each strand of one or more chromosomes specified by the user.

Usage

segChrom(y, probeAnno, chr=1, nsegs, nrBasesPerSegment = 1500, 
             step=7, confint=FALSE, confintLevel=0.95, save=FALSE, savedir=NULL)

Arguments

y ExpressionSet or matrix containing the data to be segmented.
probeAnno environment with probe annotations. See package davidTiling for an example (?probeAnno).
chr integer scalar or vector specifying which chromosome(s) to segment.
nsegs integer vector specifying the maximum number of segments (= 1 + maximum number of change points) for each chromosome and strand. If missing, this value is calculated by dividing the number of bases on a chromosome by nrBasesPerSegment.
nrBasesPerSegment integer (length 1): maximum length of a segment.
step integer, indicating the minimum distance between the consecutive probes. In cases when probes are offset by less than step bases, the probes are sampled to achieve the desired spacing.
confint logical scalar. If TRUE, confidence intervals for each change-point are calculated. Otherwise (FALSE), no confidence intervals are returned.
confintLevel numeric scalar between 0 and 1 indicating the probability level for the confidence intervals calculated for each change-point.
save logical scalar. If TRUE the results of each segmentation are saved to file in the savedir directory. If FALSE (default), the results are not saved to file.
savedir optional character string specifying the filepath where the segmentation results will be saved. Only used when save=TRUE. Defaults to current working directory.

Details

This function is a wrapper for the segment function which fits piecewise constant curves to along chromosome data. It calls segment for each strand of the chromosomes specified by the chr argument. Refer to the segment help page for further details.

Value

An environment with containing S4 objects of class "segmentation" called "1.+", "1.-", etc (depending on chr), where "+" and "-" indicates the strand and the preceding number refers to the chromosome number. If save=TRUE, a series of files, "1.+.rda", "1.-.rda", etc (depending on chr) are saved in the directory specified.

Author(s)

Matt Ritchie <ritchie@ebi.ac.uk> and Wolfgang Huber <huber@ebi.ac.uk>

Examples

## library("davidTiling")
## data("davidTiling")
## data("probeAnno")
## isDNA = seq(1:3)
## yn = normalizeByReference(davidTiling[,-isDNA],davidTiling[,isDNA], probeAnno=probeAnno)
## seg1 = segChrom(yn, probeAnno, chr=1) # this will take a while to run!

[Package tilingArray version 1.12.0 Index]