With regard to your first question, you've done it about as easily as it can be done; only other option I see is to change: 
@new_hashes = map{ my $x = $_; +{ map { $_=>$x->{$_} } @wanted_keys } 
+} @old_hashes;

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to 
@new_hashes = map { my %x; @x{@wanted_keys}=@$_{@wanted_keys}; \%x } @
+old_hashes; # untested

[download]
Update: I see someone else already said that. To provide some new content, here's a different answer to the second question: 
@cols = (split(' ', $data, 4),
         (map scalar reverse, reverse split(' ', reverse($data), 4))[1
+..3]);

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 Update: I actually "tested" that, and completely failed to notice that it did nothing like what I wanted. Try this instead: 
@cols = split(' ', $data, 4);
@cols[7,6,5,4,3] = map scalar reverse, split ' ', reverse($cols[3]), 5
+;

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or the all in one version: 
@cols = ((split(' ', $data, 4))[0..2], reverse map scalar reverse, spl
+it ' ', reverse((split ' ', $data, 4)[-1]), 5);

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Side note: ${\(expr)} does the same thing as (expr)[-1], and in fewer characters if you can omit the parentheses.

In reply to Re: Parsing bizarre non delimted data and hash slices by ysth
in thread Parsing bizarre non delimted data and hash slices by BUU

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