use strict;
use warnings;
use PDL;
use PDL::Char;

my $str = "0 X X X X X X X X 1 X X X X X X X X 2 X X X X X X X X 3 X X X X X X X X 4 X X X X X X X X 5 X X X X X X X X 6 X X X X X X X X 7";
print pp_matrix( str2matrix($str, 8, 8) );

sub str2matrix {
    # my ($str, $x, $y) = @_;
    PDL::Char->new( shift )
             ->mslice([0,-1,2])
             ->reshape(1, shift, shift);
}

sub pp_matrix {
    # my ($matrix) = @_;
    shift ->reshape(-1)
          ->append( PDL::Char->new("\n") )
          ->flat
          ->atstr(0);
}