>perl -wMstrict -le "my %Hidlabels = ('3333' => '1', '4444' => '2', '2222' => '3'); my $t = 'f3333_4444_2222 g4444_2222_3333 f4444_2222_3333 f3333 _3333'; ;; my $s = $t; $s =~ s{ (\d+) }{$Hidlabels{$1}}xmsg; print qq{'$s'}; ;; $s = $t; $s =~ s{ (?: \G (?