readMTX2IntSet {diffHic} | R Documentation

## Create an InteractionSet from a BED file and Matrix Market files

### Description

Read a set of Matrix Market Exchange Format files from disk and create an InteractionSet object.

### Usage

    readMTX2IntSet(mtx, bed, as.integer=TRUE)

### Arguments

`mtx` | A character vector containg paths to Matrix Market Exchange Format (MTX) files. Each file contains interaction read counts for one sample.
`bed` | String containing the path to the BED file specifying the genomic regions.
`as.integer` | Logical indicating whether the data should be read as integers. Otherwise values are stored in double-precision numbers.

### Details

Each MTX file is assumed to contain read counts for symmetric matrix representing the two-dimensional interaction space. Each row and column is assumed to correspond to contiguous bins of the genome, with coordinates specified by `bed` in standard BED format. This function will aggregate counts from all files to create an InteractionSet object that mimics the output of `squareCounts`.

The `width` value in the `metadata` of the output InteractionSet is set to the median width of the regions. The `totals` field in the output `colData` is also set to be equal to the sum of the counts in each MTX file. Note that these settings only make sense if the ContactMatrix objects cover binned regions.

This function can, in principle, read and merge any number of MTX files. However, for large data sets, consider reading each MTX file separately, subsetting it to interactions of interest and then creating the InteractionSet object. For example, subsetted contact matrices can be used to create an InteractionSet via `mergeCMs`.

### Value

An InteractionSet object containing interactions between regions from the BED file (in reverse-strict mode, see `GInteractions`). Each row corresponds to a unique interaction found in any of the MTX files, and contains the read counts across all files.

### Author(s)

Gordon Smyth, with modifications by Aaron Lun

### See Also

`mergeCMs`

### Examples

    library(Matrix)
    tmp.loc <- tempfile()
    dir.create(tmp.loc)

    # Mocking up some MTX and BED files.
    set.seed(110000)
    A <- rsparsematrix(1000, 1000, density=0.1, symmetric=TRUE,
        rand.x=function(n) round(runif(n, 1, 100)))
    A.name <- file.path(tmp.loc, "A.mtx")
    writeMM(file=A.name, A)

    B <- rsparsematrix(1000, 1000, density=0.1, symmetric=TRUE,
        rand.x=function(n) round(runif(n, 1, 100)))
    B.name <- file.path(tmp.loc, "B.mtx")
    writeMM(file=B.name, B)

    GR <- GRanges(sample(c("chrA", "chrB", "chrC"), 1000, replace=TRUE),
        IRanges(start=round(runif(1000, 1, 10000)),
            width=round(runif(1000, 50, 500))))
    GR <- sort(GR)
    bed.name <- file.path(tmp.loc, "regions.bed")
    rtracklayer::export.bed(GR, con=bed.name)

    # Reading everything in.
    iset <- readMTX2IntSet(c(A.name, B.name), bed.name)
    iset

[Package diffHic version 1.22.0 Index]