Calculate mean heterozygous allele balance from VCF4 files

mean_allele_balance.sh

#Automatically calculates mean heterozygous allele balance for heterozygous alleles in VCF4 files
#Allele balance must be pre-caluclated and defined for each variant in advance and given the INFO ID flag "AB" (default for GATK, etc.)

usage="usage: sh mean_allele_balance.sh <input.vcf>";
if (( $# != 1 )); then echo $usage; exit; fi

#input
VCF=$1;

#calculations
noLowQual=`grep -v ^# $VCF | grep -v "LowQual" | grep "AB=" | awk '{print $8}' | awk -F ';' '{print $1}' | awk -F '=' '{print $2}' | awk '{SUM+=$1; TOT++} END {print SUM/TOT}'`;

PassOnly=`grep -v ^# $VCF | grep "PASS" | grep "AB=" | awk '{print $8}' | awk -F ';' '{print $1}' | awk -F '=' '{print $2}' | awk '{SUM+=$1; TOT++} END {print SUM/TOT}'`;

#output
echo "Mean allele balance for all non-\"LowQual\" variants:";
echo "$noLowQual";
echo "Mean allele balance for all \"PASS\" variants:";
echo "$PassOnly";