This function writes genotype information into a binary PED (BED) filed used in plink.
For more details about this format see http://pngu.mgh.harvard.edu/~purcell/plink/binary.shtml.
Usage
write_bed(x,n,p,bed_file)
Arguments
n
integer, number of individuals.
p
integer, number of SNPs.
x
integer vector that contains the genotypic information coded as 0,1,2 and 3 (see details below).
The information must be in snp major order. The vector should be of dimension n*p with the snps stacked.