CODEWITHSUNDEEP
perlsortinghash
dff
dff

Reputation: 311

How can I sort the values of a hash in decreasing order in perl?

I am trying to use this code, but it attempts to sort the keys instead, which it cannot do because they are not numerical. 

foreach my $word (sort {$b <=> $a} keys %wordHash) {
        printf ("%-20s %10d\n", $word, $wordHash{$word});
}

Upvotes: 3

Views: 2267

Answers (1)

DVK
DVK

Reputation: 129383

  • If you want to print your hash in the values order, then you simply need to compare values in your sort block instead of comparing the keys themselves:

     { $wordHash{$b} <=> $wordHash{$a} } 
 # The rest of your code stands

    This works because the block used in sort can be ANY anonymous subroutine with arbitrary logic; as long as it returns positive/0/negative values.

  • If you only want sorted values irrespective of keys, even simpler (seems kinda pointless so I assume you wanted the previous option, but just in case I'll answer this as well): 

     sort {$b <=> $a} values %wordHash

  • Also, if you want to print in keys order but sorted alphabetically instead of numerically, default sort sorts lexically (same as { $a cmp $b }):

     sort keys %wordHash               # sort in ascending alphanumeric
 reverse sort keys %wordHash       # sort in descending alphanumeric
 sort { $b cmp $a } keys %wordHash # same: descending alphanumeric,
                                   #   faster on large data but less readable

Upvotes: 7

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