in reply to Re^2: how to set a value for a hash reference
in thread how to set a value for a hash reference

The "//" means if for a and b overlap doesn't exist then it equals zero, right?

Correct. It's the "defined-or" operator.

But where would I put this line? after the loop?

Wherever your read the values of $overlap.

Perl 6 - second systems done right

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Re^4: how to set a value for a hash reference
by AWallBuilder (Beadle) on Mar 14, 2012 at 13:34 UTC

    hmmm - I guess its a bit complicated because I"m just passing the entire hash reference to another script that writes the output in a nice matrix format. And I don't want to modify "write_R_matirx". any other suggestions? 

    use Smash::Utils::MatrixIO qw(:all);
my $SMASH_overlap_file="$CDHIT_file.smash.overlap";
write_R_matrix($SMASH_overlap_file,$overlap);

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[d/l]

      Then you do need the initialization. You could write something along the lines of 

      for my $a (@members) {
    for my $b (@memebers) {
         $overlap->{$a}{$b} = 0;
    }
}

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      before the other loop.

      Perl 6 - second systems done right
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