How about a map?

my @id_array = map { $_->{'ID'} } @array;
[download]

If you need to do a selective comparison, a grep after this operation works well:

my @sel_id_array = grep { $_ < 30 } map { $_->{'ID'} } @array;
[download]

(Also, a PM hint: use <CODE> tags instead of PRE so that you can copy and paste code directly without any markup.)

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Dr. Michael K. Neylon - mneylon-pm@masemware.com || "You've left the lens cap of your mind on again, Pinky" - The Brain