Or this: 

use warnings;
use strict;

my %h;

while (<DATA>) {
    my @cols = split;
    push @{ $h{ shift @cols } }, \@cols;
}

print $_, ' ', join( ' ' => map { $_->[0] } @{ $h{$_} } ), ' ',
               join( ' ' => map { $_->[1] } @{ $h{$_} } ), $/
  for sort { $a cmp $b } keys %h;

__DATA__
p1 cis 10
p1 plat 20
p1 gls NA
p2 cis 0
p2 NA 9

[download]

In reply to Re: How to join values of the same key that is an array of hashes? by Anonymous Monk
in thread How to join values of the same key that is an array of hashes? by BhariD

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