Re: only increment counter if the ID has not been seen before

You need to populate the hash inside the loop somehow. Here is one way:

use warnings;
use strict;

my $counter = 0;
my %hash;
while (<DATA>) {
    my @splits = split;
    my $snp = $splits[0];
    $counter++ if not exists $hash{$snp};
    print "$counter $snp\n";
    $hash{$snp}++;
}

__DATA__
foo    abc
foo    cde
bar    xyz
[download]

Prints:

1 foo
1 foo
2 bar
[download]

Comment on Re: only increment counter if the ID has not been seen before Select or Download Code

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Re^2: only increment counter if the ID has not been seen before by martin (Friar) on Mar 12, 2015 at 10:18 UTC
The OP wanted the same number in front of each occurence of the same ID, not a slowly increasing number counting different IDs so far. This can be achieved with a hash storing unique numbers rather than repetition counts. `use warnings; use strict; my $counter = 0; my %hash; while (<DATA>) { my @splits = split; my $snp = $splits[0]; $hash{$snp} \|\|= ++$counter; print "$hash{$snp} $snp\n"; } __DATA__ foo abc foo cde bar xyz foo hij` [download] This should output: `1 foo 1 foo 2 bar 1 foo` [download] ... rather than: `1 foo 1 foo 2 bar 2 foo` [download]	[reply] [d/l] [select]
Re^2: only increment counter if the ID has not been seen before by Anonymous Monk on Mar 12, 2015 at 01:21 UTC
Ah, I just needed this thing then: `$hash{$snp}++;` Damn! Thank you very much!	[reply] [d/l]