you mean plural? all keys per value?
use strict;
use warnings;
use Data::Dumper;
my %hash = (
apple => 'red',
ball => 'red',
lemon => 'yellow',
lime => 'green',
grass => 'green',
);
my %rev;
#= version 1
%rev=();
for my $value (values %hash) {
$rev{$value}=[ grep { $hash{$_} eq $value } keys %hash ];
}
print Dumper \%rev;
#= version 2
%rev=();
while (my ($k,$v) = each %hash) {
push @{ $rev{$v} }, $k ;
}
print Dumper \%rev;
#= version 2b
# not really shorter under strict ...
%rev=();
my ($k,$v);
push @{ $rev{$v} } , $k
while ( ($k,$v) = each %hash);
print Dumper \%rev;
#= version 2c
# hmm maybe finally a good application of builtin pkgvars $a and $b ;
+)
# VIVA LA AUTOVIVICACION! 8 )
%rev=();
push @{ $rev{$b} } , $a
while ( ($a,$b) = each %hash);
print Dumper \%rev;
__END__ #OUTPUT
$VAR1 = {
'green' => [
'grass',
'lime'
],
'red' => [
'apple',
'ball'
],
'yellow' => [
'lemon'
]
};
...
I'm sure there must be a modul doing this, but I couldn't find it ... at least in core-moduls ...
-
Are you posting in the right place? Check out Where do I post X? to know for sure.
-
Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
<code> <a> <b> <big>
<blockquote> <br /> <dd>
<dl> <dt> <em> <font>
<h1> <h2> <h3> <h4>
<h5> <h6> <hr /> <i>
<li> <nbsp> <ol> <p>
<small> <strike> <strong>
<sub> <sup> <table>
<td> <th> <tr> <tt>
<u> <ul>
-
Snippets of code should be wrapped in
<code> tags not
<pre> tags. In fact, <pre>
tags should generally be avoided. If they must
be used, extreme care should be
taken to ensure that their contents do not
have long lines (<70 chars), in order to prevent
horizontal scrolling (and possible janitor
intervention).
-
Want more info? How to link
or How to display code and escape characters
are good places to start.