Seems that you want to fill @subsetA and @subsetB based on the filenames contained in @fullarray.

I would propose the following apporach

• loop though each element of @fullarray
• use a regex to extract the relevant part of the filename (e.g. /(\d\d\d\d)\.tif)
• analyze the relevant part (e.g. use the modulo-operator (%) to get the reminder if of the number divided by 4)
• based on the result of the analysis, push the filename to one of your subsets

If so, do as Ratazong described, but use 2 rather than 4 in your modulo (%) statement.

Here's another way of doing it:

#!perl

use 5.12.0;
use warnings;

my @full = qw{
    0001.tif 0002.tif 0003.tif 0004.tif 0005.tif
    0006.tif 0007.tif 0008.tif 0009.tif 0010.tif
    0011.tif 0012.tif 0013.tif 0014.tif 0015.tif
    0016.tif 0017.tif 0018.tif 0019.tif 0020.tif
};
my @partioned = ([],[],[],[]);

for (0 .. $#full) {
    state $i = 0;
    push @{$partioned[$i]}, $full[$_];
    $i = ++$i % 4;
} 

my @subA = @{$partioned[0]};
my @subB = @{$partioned[1]};
my @subC = @{$partioned[2]};
my @subD = @{$partioned[3]};

say qq{@subA};
say qq{@subB};
say qq{@subC};
say qq{@subD};
[download]

Which outputs:

$ tif_split.pl
0001.tif 0005.tif 0009.tif 0013.tif 0017.tif
0002.tif 0006.tif 0010.tif 0014.tif 0018.tif
0003.tif 0007.tif 0011.tif 0015.tif 0019.tif
0004.tif 0008.tif 0012.tif 0016.tif 0020.tif
[download]

#!/usr/bin/perl

use strict;

my @array = (
'0001.tif ', "\n",
'0002.tif ', "\n",
'0003.tif ', "\n",
'0004.tif ', "\n",
'0005.tif ', "\n",
'0006.tif ', "\n",   
'0007.tif ', "\n",    
'0008.tif ', "\n",   
'0009.tif ', "\n",
'0010.tif ', "\n");

my @even = grep ($_ % 4 == 1, @array);
print "@even\n";

my @odd = grep ($_ % 4 - 1 == 1, @array);
print "@odd\n";
[download]

Your solution is great, but i want to correct it.

it must be look like

my @subA = grep( $_ % 4 == 1, 0..$#array )
my @subB = grep( $_ % 4 == 2, 0..$#array )
e.t.c.
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#!/usr/bin/perl

use strict;
use Data::PowerSet qw(powerset);

my @array = (
'0001.tif ', "\n",
'0002.tif ', "\n",
'0003.tif ', "\n",
'0004.tif ', "\n",
'0005.tif ', "\n",
'0006.tif ', "\n",   
'0007.tif ', "\n",    
'0008.tif ', "\n",   
'0009.tif ', "\n",
'0010.tif ', "\n");

my $powersetA  = powerset(
                grep ($_ % 4 == 1, @array));
for my $p(@$powersetA) {
    print @$p, "\n";
}

my $powersetB = powerset(
                grep ($_ %  4 == 2, @array));
for my $p(@$powersetB) {               
    print @$p, "\n";
}
[download]