Question

How would I split a Perl array of arbitrary size in to a variable number of smaller arrays with the number of elements in each smaller array being distibuted as evenly possible? The original array must not be destroyed.

Answer 1

Off the top of my head:

use strict;
use warnings;

use Data::Dumper; # for debugging only 

print Dumper(distribute(7, [1..30]));

# takes number+arrayref, returns ref to array of arrays
sub distribute {
    my ($n, $array) = @_;

    my @parts;
    my $i = 0;
    foreach my $elem (@$array) {
        push @{ $parts[$i++ % $n] }, $elem;
    };
    return \@parts;
};

This guarantees that number of elements in @parts may only differ by one. There’s anonther solution that would count the numbers beforehand and use splicing:

push @parts, [ @$array[$offset..$offset+$chunk] ];
$offset += chunk;
# alter $chunk if needed.