callVariantsFisher {h5vc} | R Documentation

## Paired variant calling using fisher tests

### Description

This function implements a simple paired variant calling strategy based on the fisher test

### Usage

    callVariantsPairedFisher(data, sampledata, pValCutOff = 0.05, minCoverage = 5, mergeDels = TRUE, mergeAggregator = mean)

### Arguments

`data` | A `list` with elements `Counts` (a 4d `integer` array of size [1:12, 1:2, 1:k, 1:n]), `Coverage` (a 3d `integer` array of size [1:2, 1:k, 1:n]), `Reference` (a 1d `integer` vector of size [1:n]) – see Details.
`sampledata` | A `data.frame` with `k` rows (one for each sample) and columns `Type`, `Column` and (`Group` or `Patient`). The tally file should contain this information as a group attribute, see `getSampleData` for an example.
`pValCutOff` | Maximum allowed p-Value for the fisher test on contingency matrix `matrix(c(caseCounts, caseCoverage, controlCounts, controlCoverage), nrow=2)`.
`minCoverage` | Required coverage in both sample for a call to be made
`mergeDels` | Boolean flag specifying whether adjacent deletions should be merged
`mergeAggregator` | Which function to use for aggregating the values associated with adjacent deletions that are being merged

### Details

`data` is a list which has to at least contain the `Counts`, `Coverages` and `Reference` datasets. This list will usually be generated by a call to the `h5dapply` function in which the tally file, chromosome, datasets and regions within the datasets would be specified. See `h5dapply` for specifics.

`callVariantsPairedFisher` implements a simple pairwise variant callign approach based on using the `fisher.test` on the following contingency matrix:

caseSupport | caseCoverage - caseSupport
conttrolSupport | controlCoverage - controlSupport

The results are filtered by `pValCutOff` and `minCoverage`.

### Value

The return value is a `data.frame` with the following slots:

`Chrom` | The chromosome the potential variant is on
`Start` | The starting position of the variant
`End` | The end position of the variant
`Sample` | The `Case` sample in which the variant was observed
`refAllele` | The reference allele
`altAllele` | The alternate allele
`caseCount` | Support for the variant in the `Case` sample
`caseCoverage` | Coverage of the variant position in the `Case` sample
`controlCount` | Support for the variant in the `Control` sample
`controlCoverage` | Coverage of the variant position in the `Control` sample
`pValue` | The `p.value` of the `fisher.test`

### Author(s)

Paul Pyl

### Examples

    library(h5vc) # loading library
    tallyFile <- system.file( "extdata", "example.tally.hfs5", package = "h5vcData" )
    sampleData <- getSampleData( tallyFile, "/ExampleStudy/16" )
    position <- 29979629
    windowsize <- 2000
    vars <- h5dapply( # Calling Variants
      filename = tallyFile,
      group = "/ExampleStudy/16",
      blocksize = 1000,
      FUN = callVariantsPairedFisher,
      sampledata = sampleData,
      pValCutOff = 0.1,
      names = c("Coverages", "Counts", "Reference"),
      range = c(position - windowsize, position + windowsize),
      verbose = TRUE
    )
    vars <- do.call(rbind, vars)
    vars

[Package h5vc version 2.18.0 Index]