sorting array of hashes

hotshot has asked for the wisdom of the Perl Monks concerning the following question:

Hi guys !

A tricky one. I have an array of hashes (each array entry is a hash reference). The hashes have a key named path which holds as a value a directory path, for example /usr/bin. I need to sort the array by the paths in the hashes. for example:

# if I have:
@array = (
          {
           path => '/usr/bin',    # I have other keys except the 'path
+', but it's not important here
          },
          {
           path => '/etc/init.d',
          },
          {
           path => '/root',
          }
         );
[download]

I need that the '/etc/init.d' "hash" (the hash containg this path) will be first, '/root' second, and of course '/usr/bin' last.
Anyone to the rescue?

Thanks.

Hotshot

Comment on sorting array of hashes Download Code

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Re: sorting array of hashes by Anonymous Monk on Sep 22, 2002 at 11:01 UTC
You can do it with a custom sort sub: `@array = sort { $a->{'path'} cmp $b->{'path'} } @array;` [download]	[reply] [d/l]
Re: sorting array of hashes by diotalevi (Canon) on Sep 22, 2002 at 14:55 UTC
This isn't all that hard - you just use a custom sort and prioritize your comparisons by checking for special values first. In this case I use a set of regexes as hash keys and provide a default (3) for the cases that aren't covered. This example steps on the values $aKey, $bKey, $aPri, $bPri - you could modify the code to eliminate the temporary variables. `%sort_priority = ( qr\|^/etc/init.d\| => 0, qr\|^/root\| => 1, qr\|^/usr/bin\| => 2, qr\|.?\| => 3 ); @new_array = sort { # Get the matching keys ($aKey) = grep { $a->{'path'} =~ $_ } keys %sort_priority; ($bKey) = grep { $b->{'path'} =~ $_ } keys %sort_priority; # and now their priorities $aPri = $sort_priority{$aKey}; $bPri = $sort_priority{$bKey}; # Now compare based on priority then value ($aPri == $bPri ? $a->{'path'} cmp $b->{'path'} : $aPri <=> $bPri) } @array;` [download] Update: And of course I forgot that it's a bunch of hash references. Now $a and $b are properly dereferenced	[reply] [d/l]