http://www.perlmonks.org?node_id=918549


in reply to Getting indices of the same value that occurs multiple times in an array...

>perl -wMstrict -le "my @COUNT = ( 'Family lacM taba mori glyB gly4', 'OG_1 1 0 1 0 0', 'OG_2 0 1 0 1 0', ); ;; my @families = split /\s+/, shift @COUNT; ;; my %participants; for my $record (@COUNT) { my @fields = split /\s+/, $record; $participants{$fields[0]} = [ map { $families[$_] } grep { $fields[$_] } 1 .. $#fields ]; } ;; use Data::Dumper; print Dumper \%participants; " $VAR1 = { 'OG_2' => [ 'taba', 'glyB' ], 'OG_1' => [ 'lacM', 'mori' ] };

Update: The expression
    [ map { $families[$_] } grep { $fields[$_] } 1 .. $#fields ]
is more concise and perhaps a bit faster as
    [ map $families[$_], grep $fields[$_], 1 .. $#fields ]