Another way using an on-the-fly subroutine which leaves the array untouched.

use strict;
use warnings;

my @arr = qw{ 1 1 0 2 0 1 3 0 0 4 1 1 };

sub {
        local $" = q{,};
        print qq{@{ [ map shift, 1 .. 3 ] }\n} while @_;
    }->( @arr );

print qq{@arr\n};

[download]

The output.

1,1,0
2,0,1
3,0,0
4,1,1
1 1 0 2 0 1 3 0 0 4 1 1

[download]

If the array has an element count that is not a multiple of three then add a grep to avoid "Use of uninitialized value in join or string..." warnings.

use strict;
use warnings;

my @arr = qw{ 1 1 0 2 0 1 3 0 0 4 1 1 5 7 };

sub {
        local $" = q{,};
        print qq{@{ [ grep defined, map shift, 1 .. 3 ] }\n} while @_;
    }->( @arr );

print qq{@arr\n};

[download]
1,1,0
2,0,1
3,0,0
4,1,1
5,7
1 1 0 2 0 1 3 0 0 4 1 1 5 7

[download]

I hope this is of interest.

Cheers,

JohnGG

Update: Fixed broken para tag.

Also, looking at moritz's reply, I don't know why it never occurs to me to modify output field and record separators instead of list separator. Doing so makes things much cleaner.

use strict;
use warnings;

my @arr = qw{ 1 1 0 2 0 1 3 0 0 4 1 1 5 7 };

sub {
        local( $,, $\ ) = ( q{,}, qq{\n} );
        print grep defined, map shift, 1 .. 3 while @_;
    }->( @arr );

[download]

In reply to Re: Group array in threes by johngg
in thread Group array in threes by joec_

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