package Data::Unixish::pick;
use 5.010;
use strict;
use syntax 'each_on_array'; # to support perl < 5.12
use warnings;
#use Log::Any '$log';
use Data::Unixish::Util qw(%common_args);
our $VERSION = '1.56'; # VERSION
our %SPEC;
$SPEC{pick} = {
v => 1.1,
summary => 'Pick one or more random items',
args => {
%common_args,
items => {
summary => 'Number of items to pick',
schema=>['int*' => {default=>1}],
tags => ['main'],
cmdline_aliases => { n=>{} },
pos => 0,
},
},
tags => [qw/filtering/],
};
sub pick {
my %args = @_;
my ($in, $out) = ($args{in}, $args{out});
my $n = $args{items} // 1;
my @picked;
while (my ($index, $item) = each @$in) {
if (@picked < $n) {
# we haven't reached n items, put item to picked list, in a random
# position
splice @picked, rand(@picked+1), 0, $item;
} else {
# we have reached n items, just replace an item randomly, using
# algorithm from Learning Perl, slightly modified.
rand($index+1) < @picked and
splice @picked, rand(@picked), 1, $item;
}
}
push @$out, $_ for @picked;
[200, "OK"];
}
1;
# ABSTRACT: Pick one or more random items
__END__
=pod
=encoding UTF-8
=head1 NAME
Data::Unixish::pick - Pick one or more random items
=head1 VERSION
This document describes version 1.56 of Data::Unixish::pick (from Perl distribution Data-Unixish), released on 2017-07-10.
=head1 SYNOPSIS
In Perl:
use Data::Unixish qw(lduxl);
my @pick = lduxl([pick => {items=>2}], 1..100); # => (52, 33)
In command line:
% seq 1 100 | dux pick -n 4
.-------------------.
| 18 | 22 | 2 | 24 |
'----+----+----+----'
=head1 FUNCTIONS
=head2 pick
Usage:
pick(%args) -> [status, msg, result, meta]
Pick one or more random items.
This function is not exported.
Arguments ('*' denotes required arguments):
=over 4
=item * B<in> => I<array>
Input stream (e.g. array or filehandle).
=item * B<items> => I<int> (default: 1)
Number of items to pick.
=item * B<out> => I<any>
Output stream (e.g. array or filehandle).
=back
Returns an enveloped result (an array).
First element (status) is an integer containing HTTP status code
(200 means OK, 4xx caller error, 5xx function error). Second element
(msg) is a string containing error message, or 'OK' if status is
200. Third element (result) is optional, the actual result. Fourth
element (meta) is called result metadata and is optional, a hash
that contains extra information.
Return value: (any)
=head1 HOMEPAGE
Please visit the project's homepage at L<https://metacpan.org/release/Data-Unixish>.
=head1 SOURCE
Source repository is at L<https://github.com/perlancar/perl-Data-Unixish>.
=head1 BUGS
Please report any bugs or feature requests on the bugtracker website L<https://rt.cpan.org/Public/Dist/Display.html?Name=Data-Unixish>
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.
=head1 AUTHOR
perlancar <perlancar@cpan.org>
=head1 COPYRIGHT AND LICENSE
This software is copyright (c) 2017, 2016, 2015, 2014, 2013, 2012 by 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.
=cut