in reply to Sorting or Aligning Parallel Hashes

Your analysis of the problem is quite accurate. If you do those steps, one at a time, you get what you want. Keep in mind that hashes can't be sorted, just their keys and/or values.

I would like to sort Hash “A” (key) in descending order
my @sorted_scores = sort { $b <=> $a } keys %HashA;

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and then align the (value) Hash “A” with Hash “B” (key).
my @sorted_words = map { $HashA{$_} } @sorted_scores;

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Then use that sort, to align Hash “C” so that the key value pairs of "C" can be printed out in the same order as the sorted “A” Hash.
my @sorted_line_nums = map { $HashB{$_} } @sorted_words;

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And the print: 

print($HashC{$_}, "\n");
   foreach @sorted_line_nums;

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All together now: 

print("$_\n");
   foreach map { $HashC{$HashB{$HashA{$_}}} }
           sort { $b <=> $a }
           keys %HashA;

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I'm curious as to how you handle two lines having the same score, if the score is the key.

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Re^2: Sorting or Aligning Parallel Hashes
by Gavin (Archbishop) on Mar 29, 2006 at 11:12 UTC
    Thanks very much for the help.
    Could you explain further how to use the sorted hash "A" to align the second hash "B"
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      There's no such thing as a sorted hash(*), and I don't know what kind of terminology "align" is. You're confusing yourself by trying to be technical. Your data does NOT consist of unsorted hashes, sorted hashes and alignments; your data consists of scores, keywords, line numbers, text and the relationships between them.

      Your question is then "Could you explain further how to get the keywords for a list of (sorted) scores?" I used: 

      my @sorted_words = map { $HashA{$_} } @sorted_scores;

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      I could also have used: 
      my @sorted_words;
foreach (@sorted_scores) {
   push(@sorted_words, $HashA{$_};
}

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      %HashA defines the relationship between scores and keywords. To get a list of keywords for a list of scores, simply loop over all the scores and use %HashA to find the corresponding keywords.

      * - Well, it's possible using tie, but that's neither needed nor relevant here.

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        I don't get why you didn't use a hash slice. 
        my @sorted_words = @HashA{@sorted_scores};

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           push(@sorted_words = $HashA{$_};

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        That is sooo wrong, I can't believe you wrote that. 
           push @sorted_words, $HashA{$_};

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