Hi Meir,
On Sat, 20 Jul 2013 15:33:06 +0300
Meir Guttman <m...@guttman.co.il> wrote:
> Hello Perlers,
> Sometimes I would like to swap the order of the two keys of a
> TWO-DIMENTIONAL hash. I could of course do it in a straight forward way as:
> my %original;
> my %swapped;
> foreach my $major_key (keys %original){
> foreach my $minor_key (keys %original{$major_key}){
> $swapped{$minor_key}{$major_key} = $original{$major_key}{$minor_key};
> }
> }
> Simple enough!
> I wonder though how can I use 'map' in such a case, or can I?
I can't think of a good and efficient way to do it using 'map' alone, because
you swap the order of the nestings. You can write a subroutine that accepts two
hash references and does the swapping for you like you demonstrated.
BTW, you can save a little by doing «my $orig_major_val =
$original{$major_key}» or perhaps by using each() instead of «foreach ..
keys» (though I was told each() is not always receommended.
Regards,
Shlomi Fish
> Or is there a utility for that?
> I do it a lot, and performance matters...
> Meir
>
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