Simply test the keys against your pattern: 

foreach my $key ( keys %hash )
{
    if( $key =~ m/\d+_\d+/ )
    {
         print "key = $key, value = $hash{$key}\n";
    }
}

[download]

Or am I missing something?

HTH

Update: I forgot about the "modify hash" requirement - sorry. merlyn came up with a great one-liner, of course!

In reply to Re: Selecting particular key-value pairs in hashes by bobf
in thread Selecting particular key-value pairs in hashes by kiat

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