A good way to resolve data structure confusion is to use Data::Dumper from CPAN and view your data structure:

use Data::Dumper;
print STDERR "This is confusing: ",Dumper($someConfusingStructure),"\n
+";
[download]

Then you can see exactly what you're dealing with and perhaps come up with a solution faster than you would be asking the general public.

In any case, the above posters are correct that a map cannot solve your problem without making things slower and more complicated. I can see it being done by nesting maps and putting extra conditions inside the map block, but that's much slower than a single loop and pushing arrays.