NAME
List::Categorize - Categorize list items into a hash of named sublists
VERSION
This documentation describes List::Categorize version 0.01.
SYNOPSIS
use List::Categorize qw(categorize);
my %odds_and_evens = categorize { $_ % 2 ? 'ODD' : 'EVEN' } (1..9);
# %odds_and_evens now contains
# ( ODD => [ 1, 3, 5, 7, 9 ], EVEN => [ 2, 4, 6, 8 ] )
my %capitalized = categorize {
# Transform the element before placing it in the hash.
$_ = ucfirst $_;
# Use the first letter of the element as the category.
substr($_, 0, 1);
} qw( apple banana antelope bear canteloupe coyote );
# %capitalized now contains
# (
# A => [ 'Apple', 'Antelope' ],
# B => [ 'Banana', 'Bear' ],
# C => [ 'Canteloupe', 'Coyote' ]
# )
DESCRIPTION
A simple module that creates a hash by applying a specified rule to each element of a provided list.
EXPORT
Nothing by default.
SUBROUTINES
categorize BLOCK LIST
my %hash = categorize { $_ > 10 ? 'Big' : 'Little' } @list;
categorize
creates a hash by running BLOCK for each element in LIST. The block returns a hash key (the "category") for the current element. (If it returns undef
for a list element, that element is not placed in the resulting hash.)
The resulting hash contains a key for each category, and each key refers to a list of the elements that correspond to that category.
Within the block, $_ refers to the current list element. Elements can be modified before they're placed in the target hash by modifying the $_ variable:
my %hash = categorize { $_ = uc $_; 'List' } qw( one two three );
# %hash now contains ( List => [ 'ONE', 'TWO', 'THREE' ] )
NOTE: The categorizer should return a string, or undef
. Other values are reserved for future use, and may cause unpredictable results in the current version.
SEE ALSO
AUTHOR
Bill Odom, <wnodom at cpan.org>
BUGS
None known.
Please report any bugs or feature requests to bug-list-categorize at rt.cpan.org
, or through the web interface at http://rt.cpan.org/NoAuth/ReportBug.html?Queue=List-Categorize.
SUPPORT
You can find documentation for this module with the perldoc command.
perldoc List::Categorize
You can also look for information at:
RT: CPAN's request tracker
AnnoCPAN: Annotated CPAN documentation
CPAN Ratings
Search CPAN
COPYRIGHT & LICENSE
Copyright (c) 2009 Bill Odom.
This module is free software; you can redistribute it and/or modify it under the same terms as Perl 5.10.0. For more details, see the full text of the licenses at http://www.perlfoundation.org/artistic_license_1_0, and http://www.gnu.org/licenses/gpl-2.0.html.
This program is distributed in the hope that it will be useful, but without any warranty; without even the implied warranty of merchantability or fitness for a particular purpose.