subset a bigWig file

bwview.sh

#!/usr/bin/env bash

#Script to subset a bigWig file for user specific loci
#MIT License (Anand Mayakonda; anandmt3@gmail.com)

function usage (){
   echo "Subset a bigWig file for genomic loci. 

Requires UCSC kentutils bigWigToBedGraph and bedGraphToBigWig to be installed
Binaries available from: https://hgdownload.soe.ucsc.edu/admin/exe/

positional arguments:
  <bigWig>   Input bigWig file
  <REGION>   Genomic region to subset. e.g: chr6:31125776-31144789

optional arguments  :
  -o        Output basename. Default <REGION>
  -r        UCSC ref genome build. Default hg19

Usage:   bwview [options] <bigWig> <REGION>
Example: bwview -r hg38 foo.bw chr6:31125776-31144789
" 1>&2
}

DB="hg19"
out=""
bigWig=""
REGION=""

while getopts "h?r:o:" OPTION
    do
        case "${OPTION}" in
        h)
            usage
            exit 1
            ;;
        r)
            DB="$OPTARG"
            ;;
        o)
            out="$OPTARG"
            ;;
        ?)
            unkOpt="$OPTARG"
            echo -e "Unknown option: ${unkOpt}"
            usage
            exit
            ;;
        esac
done

bigWig="${@:$((${OPTIND})):1}"
REGION="${@:$((${OPTIND}+1)):1}"

if [[ -z "${bigWig}" ]]
    then
    usage
    echo "Missing <bigWig>" 1>&2
    exit 1
fi

if [[ -z "${REGION}" ]]
    then
    usage
    echo "Missing <REGION>" 1>&2
    exit 1
fi

#Check if required kent utils exist
if [[ -z `which bigWigToBedGraph` ]]; then
    echo -e "bigWigToBedGraph not found! Get it from here: https://hgdownload.soe.ucsc.edu/admin/exe/"
    exit
fi

if [[ -z `which bedGraphToBigWig` ]]; then
    echo -e "bedGraphToBigWig not found! Get it from here: https://hgdownload.soe.ucsc.edu/admin/exe/"
    exit
fi

chr=$(echo ${REGION} | cut -f 1 -d ':')
loc=$(echo ${REGION} | cut -f 2 -d ':')
start=$(echo ${loc} | cut -f 1 -d '-' | sed 's/,//g')
end=$(echo ${loc} | cut -f 2 -d '-' | sed 's/,//g')


#Below chunk from ucsc fetchChroSizes
echo "Fetching chrom sizes.." 1>&2

if [[ -z "${out}" ]]; then
    out="${chr}_${start}_${end}"
fi

export DB
if [ -z "${DB}" ]; then
    usage
fi

DONE=0
export DONE

url="http://hgdownload.soe.ucsc.edu/goldenPath/${DB}/bigZips/${DB}.chrom.sizes"
if [ "$DB" == "hg19" -o "$DB" == "hg38" ] ; then
    #printf "INFO: Using latest patch release of genome for hg19/hg38\n" 1>&2
    url="http://hgdownload.soe.ucsc.edu/goldenPath/${DB}/bigZips/latest/${DB}.chrom.sizes"
fi

tmpResult=${DB}.tmp.sizes$$
curl ${url} \
-s > ${tmpResult} 2> /dev/null
if [ $? -ne 0 -o ! -s "${tmpResult}" ]; then
    printf "WARNING: curl command failed\n" 1>&2
    rm -f "${tmpResult}"
else
    #
    if [[ ${chr} != chr* ]]; then
      echo "Removing chr prefix from chrom.sizes file.." 1>&2
      cat ${tmpResult} | sed 's/^chr//' > ${DB}.chrom.sizes 
    else
      cat ${tmpResult} > ${DB}.chrom.sizes 
    fi
    rm -f "${tmpResult}"
    DONE=1
fi

#Convert bigWig to bedGraph to bigWIg
bigWigToBedGraph -chrom=${chr} -start=${start} -end=${end} ${bigWig} ${out}.bedgraph
bedGraphToBigWig ${out}.bedgraph ${DB}.chrom.sizes ${out}.bw

if [[ -f ${out}.bw ]];then
  echo "Done!" 1>&2
fi

rm -f ${out}.bedgraph
rm -f ${DB}.chrom.sizes