I tried to get the first part of this code working but wasn't successful (see below). I had a problem using the map-function.
Can someone explain me why it doesn't work as presented here?
Thanks, 

#!/usr/bin/perl -w
use strict;

#define your data:
my %hash = (
    .1 => 'url1',
    .2 => 'url2',
    .3 => 'url3',
    .7 => 'url7',
    .9 => 'url9',
);

## It works if I use this loop
# my @good_keys;
# foreach my $key ( keys %hash ) {
#     if ( $key > .4 ) {
#         push @good_keys, $key;
#     }
# 
# }

# but I can not get it to work with this map-function
#define the fitness function / match determination
my $good_value = sub { $_ > 0.4 };


#find the keys that match the fitness function:
my @good_keys = map { $good_value->($_) } keys %hash;


#now do something with the keys:
##eg. print the values, in hash order:
for my $key (@good_keys) {
    print $hash{$key}, "\n";
}

[download]

In reply to Re^3: Hash table manipulation by GertMT
in thread Hash table manipulation by sarvan

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