BEDMatrix is an R package that provides a matrix-like wrapper around .bed, one of the genotype/phenotype file formats of PLINK, the whole genome association analysis toolset. BEDMatrix objects are created in R by simply providing the path to a .bed file and once created, they behave similarly to regular matrices with the advantage that genotypes are retrieved on demand without loading the entire file into memory. This allows handling of very large files with limited use of memory.
This package is deliberately kept simple. For computational methods that use BEDMatrix check out the BGData package.
This example uses a dummy .bed file that is bundled with this R
package. It was generated using
plink --dummy 500 1000 0.02 acgt --seed 4711 --out example
with PLINK 1.90 beta 3.452.
To get the path to the example .bed file (system.file
finds the full file names of files in packages and is only used to find
the example data):
path <- system.file("extdata", "example.bed", package = "BEDMatrix")To wrap the example .bed file in a BEDMatrix object:
m <- BEDMatrix(path)
#> Extracting number of samples and rownames from example.fam...
#> Extracting number of variants and colnames from example.bim...To get the dimensions of the BEDMatrix object:
dim(m)
#> [1] 50 1000To extract a subset of the BEDMatrix object:
m[1:3, 1:5]
#> snp0_A snp1_C snp2_G snp3_G snp4_G
#> per0_per0 0 1 1 1 0
#> per1_per1 1 1 1 1 NA
#> per2_per2 1 0 0 2 0Install the stable version from CRAN:
install.packages("BEDMatrix")Alternatively, install the development version from GitHub:
# install.packages("remotes")
remotes::install_github("QuantGen/BEDMatrix")Further documentation can be found on RDocumentation.