Re: Using map to create a hash/bag from an array

[osunderdog]

Well, it seems to work... So that's certainly a good start. I use two alternatives for this. It depends on whether I need to know the frequency of items or if I need more set like semantics.

Here is the bag example:

use strict;
use Data::Dumper;

my @items = ('this', 'that', 'that', 'those', 'these', 'them', 'thou')
+;

my $bag;
map {$bag->{$_}++} @items;

print Dumper($bag);

__END__

$VAR1 = {
          'these' => 1,
          'those' => 1,
          'thou' => 1,
          'them' => 1,
          'that' => 2,
          'this' => 1
        };

And here is the set example:

use strict;
use Set::Scalar;
use Data::Dumper;

my @items = ('this', 'that', 'that', 'those', 'these', 'them', 'thou')
+;
my $set = Set::Scalar->new(@items);

print Dumper($set->members);

__END__


$VAR1 = 'those';
$VAR2 = 'these';
$VAR3 = 'thou';
$VAR4 = 'them';
$VAR5 = 'that';
$VAR6 = 'this';

[mrborisguy]

Why not use for in this example, since you're not really transforming @items into a new array (common use of map), but rather just performing an action for each value in @items (common use of for).

$bag->{$_}++ for @items;
  # instead of
map {$bag->{$_}++} @items;

    -Bryan