in reply to Re^4: counting the number of 16384 pattern matches in a large DNA sequence
in thread counting the number of 16384 pattern matches in a large DNA sequence

I would expect swapping 
        my @matches = ($seq{$key} =~ /$string/ig);
        #print "@matches\n";
        $result{$string} = scalar(@matches);

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to

        $result{$string} =()= ($seq{$key} =~ /$string/ig);

would hit the spec of this request, but I would also expect the speed-up achieved would be negligible. The compound of two = operators with an empty list (()) puts the regex in list context, thus obtaining a count of all matches.

#11929 First ask yourself `How would I do this without a computer?' Then have the computer do it the same way.

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Re^6: counting the number of 16384 pattern matches in a large DNA sequence
by anonym (Acolyte) on Jun 14, 2012 at 20:20 UTC

    Thanks.I tried this line 

    $result{$string} =()= ($seq{$key} =~ /$string/ig);

    [download]

    but it is nt printing anything.

[reply]
[d/l]
      As described in I know what I mean. Why don't you?, come up with a simple, replicatable piece of code that displays the bug. For example, 
      use strict;
use warnings;

my %result;
my %seq = (key => 'asdfasdfasdf');
my @string = 'asdf';

foreach my $string (@string) {
    chomp $string;
    foreach my $key (keys %seq) {
        $result{$string} =()= ($seq{$key} =~ /$string/ig); 
    }

    foreach my $s (keys %result) {
        print "$s => $result{$s}\n";
    }
}

      [download]
      outputs asdf => 3 as expected.

      #11929 First ask yourself `How would I do this without a computer?' Then have the computer do it the same way.

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