NAME

Array::Pick::Scan - Pick random items from an array (or iterator), without duplicates

VERSION

This document describes version 0.005 of Array::Pick::Scan (from Perl distribution Array-Pick-Scan), released on 2022-05-21.

SYNOPSIS

 use Array::Pick::Scan qw(pick);

 my $item  = pick(\@ary);
 my @items = pick(\@ary, 3);

or:

 my $item  = pick(\&iterator);
 my @items = pick(\&iterator, 3);

To return array indexes instead of the items:

 my @item  = pick($source, $n, {pos=>1});

DESCRIPTION

This module can return random items from an array (or iterator), without duplicate elements (i.e. random sampling without replacement). It uses the same algorithm as File::Random::Pick, which in turn uses a slightly modified version of algorithm described in perlfaq ("perldoc -q "random line"")), but uses items from an array/iterator instead of lines from a file(handle).

Performance-wise, this module is inferior to List::Util's shuffle or List::MoreUtils's samples, but can be useful in cases where you have an iterator and do not want to put all the iterator's items into memory first.

FUNCTIONS

pick

Usage:

 my @items = pick(\@ary      [ , $num_samples [ , \%opts ] ]);
 my @items = pick(\&iterator [ , $num_samples [ , \%opts ] ]);

Number of samples defaults to 1.

Options:

• pos

  Bool. If set to true, will return array indexes instead of the items.

random_item

Older name for "pick", deprecated and will be removed in future releases.

HOMEPAGE

Please visit the project's homepage at https://metacpan.org/release/Array-Pick-Scan.

SOURCE

Source repository is at https://github.com/perlancar/perl-Array-Pick-Scan.

SEE ALSO

File::Random::Pick uses a similar algorithm.

List::Util's shuffle, List::MoreUtils's samples, List::AllUtils's sample.

Array::Sample::SimpleRandom provides random sampling without replacement (same as picking in this module) as well as with replacement (creating possible duplicate items).

Array::Sample::WeightedRandom lets you add weighting to each item.

AUTHOR

perlancar <perlancar@cpan.org>

CONTRIBUTING

To contribute, you can send patches by email/via RT, or send pull requests on GitHub.

Most of the time, you don't need to build the distribution yourself. You can simply modify the code, then test via:

 % prove -l

If you want to build the distribution (e.g. to try to install it locally on your system), you can install Dist::Zilla, Dist::Zilla::PluginBundle::Author::PERLANCAR, and sometimes one or two other Dist::Zilla plugin and/or Pod::Weaver::Plugin. Any additional steps required beyond that are considered a bug and can be reported to me.

COPYRIGHT AND LICENSE

This software is copyright (c) 2022, 2020 by perlancar <perlancar@cpan.org>.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

BUGS

Please report any bugs or feature requests on the bugtracker website https://rt.cpan.org/Public/Dist/Display.html?Name=Array-Pick-Scan

When submitting a bug or request, please include a test-file or a patch to an existing test-file that illustrates the bug or desired feature.

cpanm Array::Pick::Scan

perl -MCPAN -e shell
install Array::Pick::Scan