#!/usr/bin/perl -w
use strict;

my %HoA = (
   key1 => [ "50001", "01" ],
   key2 => [ "50011", "02" ],
   key3 => [ "50010", "01" ],
   key4 => [ "50041", "02" ],
   key5 => [ "50301", "02" ],
   key6 => [ "50701", "09" ],
   key7 => [ "50801", "09" ]
);

my %containers;
while (my ($k, $v) = each (%HoA)) {
    push @{$containers{$v->[0]}}, $k;
}

foreach (sort keys %containers) {
    print "Container $_ has ".@{$containers{$_}}." keys.\n"
}

[download]
This retains the keys in the `%containers` hash, if you don't need to do that you could replace the loops with: 
my %containers;
while (my ($k, $v) = each (%HoA)) {
    $containers{$v->[1]}++;
}

foreach (sort keys %containers) {
    print "Container $_ has $containers{$_} keys.\n"
}

[download]

In reply to Re: Count array element in HASH of ARRAYS by halfcountplus
in thread Count array element in HASH of ARRAYS by stm

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