http://www.perlmonks.org?node_id=1057115


in reply to hash of hashes

This is probably what you are looking for:
use strict; my %byColor; while (<DATA>){ my ($fruit, @colors) = split; for my $c(@colors){ push @{ $byColor{$c} }, $fruit; } } for my $c(sort keys %byColor){ print "$c\t @{$byColor{$c}}\n"; } __DATA__ strawberry red green rose apple red rose mango green
Output:
green strawberry mango red strawberry apple rose strawberry apple

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