perl_list_helpers_xs

NAME

List::Helpers::XS - Perl extension to provide some usefull functions with arrays

SYNOPSIS

  use List::Helpers::XS qw/ :shuffle :slice /;

  my $slice = random_slice(\@list, $size); # returns array reference, @list is partitial shuffled

  random_slice(\@list, $size); # @list is now truncated and shuffled

  shuffle(\@list);
  shuffle(@list);

  # undef value will be skipped
  shuffle_multi(\@list1, \@list2, undef, \@list3);

  # the same for tied arrays

  tie(@list, "MyPackage");
  shuffle(@list);
  shuffle(\@list);
  my $slice = random_slice(\@list, $size); # returns array reference

DESCRIPTION

This module provides some rare but usefull functions to work with arrays.
It supports tied arrays.

random_slice

This method receives the array and the amount of required elements to be shuffled,
shuffles array's elements and returns the array reference to the new
arrays with C<num> elements from original one.

If "num" is equal or higher than amount of elements in array, then it
won't do any work.

It doesn't shuffle the whole array, it shuffle only "num" elements and
returns only them.

This method can a bit slow down in case of huge arrays and "num",
because of it copies chosen elements into the new array to be returned

In this case please consider the usage of "random_slice" method.

Also the original array will be shuffled at the end.

In void context the original list will be truncated and shuffled.

shuflle

  Shuffles the provided array.
  Doesn't return anything.

shuffle_multi

Shuffles multiple arrays.
Each array must be passed as array reference.
All undefined arrays will be skipped.
This method will allow you to save some time by getting rid of extra calls.
You can pass so many arguments as Perl stack allows.

Benchmarks

Benchmarks of "random_slice" method in comparison with
"List::MoreUtils::samples" and "List::Util::sample" showed that current
version of "random_slice" is very similar to the first ones in some
cases. But in case of huge amount of iterations it starts to slow down
due to some performance degradation.

So, the usage of "List::MoreUtils::samples" (it's the fastest now) and
"List::Util::sample" is more preferable. I'll keep "random_slice" for
backward compatibility.

The benchmark results for "shuffle"

                            shuffle_huge_array  List::Helpers::XS::shuffle
shuffle_huge_array                          --                         -5%
List::Helpers::XS::shuffle                  5%                          --

                            shuffle_array  List::Helpers::XS::shuffle
shuffle_array                          --                         -4%
List::Helpers::XS::shuffle             4%                          --

                            List::Util::shuffle  List::Helpers::XS::shuffle
List::Util::shuffle                          --                        -63%
List::Helpers::XS::shuffle                 170%                         --

AUTHOR

Chernenko Dmitriy, cdn@cpan.org

COPYRIGHT AND LICENSE

Copyright (C) 2021 by Dmitriy

This library is free software; you can redistribute it and/or modify it
under the same terms as Perl itself, either Perl version 5.26.1 or, at
your option, any later version of Perl 5 you may have available.