tsk1979 has asked for the wisdom of the Perl Monks concerning the following question:

Hi have data present in 3 arrays key1, key2 and data The number of elements in the three arrays is same. I have to write all the elements in a file as 
$key1[0]
$key2[0]
$data[0]

$key1[1]
$key2[1]
$data[1]
.
.
.
.

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Pretty simple, eh? But there is a problem. If while parsing, a $data has appeared before, that should not be in the file. So lets say $data[45] has come before, in that case 
$key1[45]
$key2[45]
$data[45]

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Should not be dumped in the file. So I am uniquifying an array(which is pretty simple in itself), and controlling the printing of 2 other arrays using this. Any tips welcome!

Replies are listed 'Best First'.
Re: Array unification problem has me in circles
by graff (Chancellor) on Nov 07, 2007 at 09:02 UTC 
    my %seen;
for (0..$#data) {
    next if ( $seen{$data[$_]}++ );
    print join "\n", $key1[$_], $key2[$_], $data[$_], "";
}

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[d/l]
Re: Array unification problem has me in circles
by moritz (Cardinal) on Nov 07, 2007 at 09:03 UTC
    You can store strings in a hash as the hash keys, and while writing to your file you can always consult the hash to check if that key has already been printed.
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Re: Array unification problem has me in circles
by tuxz0r (Pilgrim) on Nov 07, 2007 at 17:58 UTC
    I'm not sure how you are looping through those arrays, but an easy way to make @data contain only unique items might go like so: 
    my %tmp = map { $_ => 1} @data;
my @uniq_data = sort keys %tmp;

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    Then, just use that to loop through the other structures, outputing defined keys only once.

    ---
    echo S 1 [ Y V U | perl -ane 'print reverse map { $_ = chr(ord($_)-1) } @F;'
    Warning: Any code posted by tuxz0r is untested, unless otherwise stated, and is used at your own risk.

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[d/l]
      Or, written more cleanly: 
      use List::MoreUtils qw( uniq );

my @uniq_data = uniq @data;

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      My criteria for good software:
      1. Does it work?
      2. Can someone else come in, make a change, and be reasonably certain no bugs were introduced?
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[d/l]

      Could avoid setting the 1s since values are absolutely being ignored, but it's a two step process ... 

      my %tmp;
@tmp{ @data } = ();

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[d/l]

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