Re: Confusion due to hash

I'm not quite sure where you are going with this, but it seems to me that you need two hashes:

use strict;
use warnings;
use Data::Dumper;

my %hash= (10=>1, 20=>2, 30=>1, 40=>2);
my %rhash;

map {$rhash{$hash{$_}} += $_} keys %hash;

print Dumper (\%hash);
print Dumper (\%rhash);
[download]

Prints:

$VAR1 = '%hash';
$VAR2 = {
          '40' => 2,
          '30' => 1,
          '10' => 1,
          '20' => 2
        };
$VAR1 = '%rhash';
$VAR2 = {
          '1' => 40,
          '2' => 60
        };
[download]

DWIM is Perl's answer to Gödel

Comment on Re: Confusion due to hash Select or Download Code

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Re^2: Confusion due to hash by duckyd (Hermit) on Jan 31, 2006 at 01:44 UTC
reverse is useful to get the output in the desired format: `use strict; use warnings; use Data::Dumper; my %input = (10=>1, 20=>2, 30=>1, 40=>2); my %output; map { $output{ $input{ $_ } } += $_ } keys %input; %output = reverse %output; print Dumper \%output;` [download] Prints: `$VAR1 = { '60' => '2', '40' => '1' };` [download] Update: I paid to much attention to the requested output, and not enough to the note that he couldn't reverse the hash	[reply] [d/l] [select]
Re^3: Confusion due to hash by GrandFather (Saint) on Jan 31, 2006 at 01:51 UTC
Except that OP says And how do I check if a value exists? I can not reverse the hash since it has many of the same values. in which case leaving %rhash in its original form allows the lookup that OP wants - no reversing required. DWIM is Perl's answer to Gödel	[reply]