Shell Programming and Scripting

ABC  6
ABC 22
ABC 44
ABC 56
XYZ 12
XYZ 23
XYZ 42
DEF  2
DEF  14
DEF  24

nawk '{c[$1]++;s[$1]+=$2}END{ for(i in c) printf("%s %.2f\n", i, s[i]/c[i])}' myFile

awk '{ T[$1]+=$2; C[$1]++} END { for(K in C) print K, T[K]/C[K] }' < file

$
$
$ cat f21
ABC  6
ABC 22
ABC 44
ABC 56
XYZ 12
XYZ 23
XYZ 42
DEF  2
DEF  14
DEF  24
$
$
$ perl -lane 'if ($F[0] ne $i and $.>1){print $i,"\t",($j/$n); $j=$F[1]; $n=1} else{$n++; $j+=$F[1]} $i=$F[0]; END{print $i,"\t",($j/$n)}' f21
ABC     32
XYZ     25.6666666666667
DEF     13.3333333333333
$
$
$