Split bedfile by chromosome and chunk size #bed

split_bed.sh

function split_bed() {
# This function will split a bed file by chromosome and chunk_size=1000
# In other words, split files will only possess one chromosome max.
# File sizes may be variable.
awk -v chunk_size=1000 'NR == 1 { chrom=$1; iter=0; fname_iter=0; print chrom } 
    {
            if(chrom == $1 && iter <= chunk_size) {
                print > sprintf("x%04d_%s.segment.txt", fname_iter, $1);
                iter++; 
            } else {
                chrom=$1;
                iter=0;
                fname_iter++;
            }
    }' $1
}
split_bed SureSelectV5_TRACERx_Edition.bed