segmentationCBS {PureCN} | R Documentation

## CBS segmentation

### Description

The default segmentation function. This function is called via the `fun.segmentation` argument of `runAbsoluteCN`. The arguments are passed via `args.segmentation`.

### Usage

    segmentationCBS(normal, tumor, log.ratio, seg, plot.cnv, sampleid,
      target.weight.file = NULL, alpha = 0.005, undo.SD = NULL, vcf = NULL,
      tumor.id.in.vcf = 1, normal.id.in.vcf = NULL, max.segments = NULL,
      prune.hclust.h = NULL, prune.hclust.method = "ward.D", chr.hash = NULL,
      centromeres = NULL)

### Arguments

`normal` | Coverage data for normal sample.
`tumor` | Coverage data for tumor sample.
`log.ratio` | Copy number log-ratios, one for each target in the coverage files.
`seg` | If segmentation was provided by the user, this data structure will contain this segmentation. Useful for minimal segmentation functions. Otherwise PureCN will re-segment the data. This segmentation function ignores this user provided segmentation.
`plot.cnv` | Segmentation plots.
`sampleid` | Sample id, used in output files.
`target.weight.file` | Can be used to assign weights to targets.
`alpha` | Alpha value for CBS, see documentation for the `segment` function.
`undo.SD` | `undo.SD` for CBS, see documentation of the `segment` function. If NULL, try to find a sensible default.
`vcf` | Optional `CollapsedVCF` object with germline allelic ratios.
`tumor.id.in.vcf` | Id of tumor in case multiple samples are stored in VCF.
`normal.id.in.vcf` | Id of normal in in VCF. Currently not used.
`max.segments` | If not `NULL`, try a higher `undo.SD` parameter if number of segments exceeds the threshold.
`prune.hclust.h` | Height in the `hclust` pruning step. Increasing this value will merge segments more aggressively. If NULL, try to find a sensible default.
`prune.hclust.method` | Cluster method used in the `hclust` pruning step. See documentation for the `hclust` function.
`chr.hash` | Mapping of non-numerical chromsome names to numerical names (e.g. chr1 to 1, chr2 to 2, etc.). If `NULL`, assume chromsomes are properly ordered.
`centromeres` | A `GRanges` object with centromere positions. Currently not supported in this function.

### Value

`data.frame` containing the segmentation.

### Author(s)

Markus Riester

### References

Olshen, A. B., Venkatraman, E. S., Lucito, R., Wigler, M. (2004). Circular binary segmentation for the analysis of array-based DNA copy number data. Biostatistics 5: 557-572.

Venkatraman, E. S., Olshen, A. B. (2007). A faster circular binary segmentation algorithm for the analysis of array CGH data. Bioinformatics 23: 657-63.

### See Also

`runAbsoluteCN`

### Examples

    normal.coverage.file <- system.file("extdata", "example_normal.txt",
        package="PureCN")
    tumor.coverage.file <- system.file("extdata", "example_tumor.txt",
        package="PureCN")
    vcf.file <- system.file("extdata", "example_vcf.vcf.gz",
        package="PureCN")
    interval.file <- system.file("extdata", "example_intervals.txt",
        package="PureCN")

    # The max.candidate.solutions, max.ploidy and test.purity parameters are set to
    # non-default values to speed-up this example.  This is not a good idea for real
    # samples.
    ret <-runAbsoluteCN(normal.coverage.file=normal.coverage.file,
        tumor.coverage.file=tumor.coverage.file, vcf.file=vcf.file, genome="hg19",
        sampleid="Sample1", interval.file=interval.file,
        max.candidate.solutions=1, max.ploidy=4, test.purity=seq(0.3,0.7,by=0.05),
        fun.segmentation=segmentationCBS, args.segmentation=list(alpha=0.001))

[Package PureCN version 1.10.0 Index]