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Re^4: Is there a way to compare strings without using an array?

by Jeri (Scribe)
on Oct 18, 2011 at 20:32 UTC ( #932242=note: print w/ replies, xml ) Need Help??


in reply to Re^3: Is there a way to compare strings without using an array?
in thread Is there a way to compare strings without using an array?

I like the List::Compare. It looks good. I'm just worried about, because my array will be at least 5 million in length. Can you offer me any peace of mind?


Comment on Re^4: Is there a way to compare strings without using an array?
Re^5: Is there a way to compare strings without using an array?
by tj_thompson (Scribe) on Oct 18, 2011 at 21:04 UTC

    Abstract your comparison code out into a subroutine and give it a try. Should be quick simple code to write and you'll know exactly how well it performs. Will make changing the code or comparing it to other possible solutions simple as well.

Re^5: Is there a way to compare strings without using an array?
by CountZero (Bishop) on Oct 19, 2011 at 16:12 UTC
    Here is some code which does what you want:
    use Modern::Perl; use List::Compare; # Make two arrays with fake data my @left = map {'AA' . int(rand (5000000) + 1000000)} (1 ... 5000000) +; my @right = map {'AA' . int(rand (5000000) + 1000000)} (1 ... 5000000) +; my $start = time; my $lc = List::Compare->new('-u', \@left, \@right); { open my $OUT_INTER, '>', './intersection.txt'; say $OUT_INTER $_ for $lc->get_intersection; } { open my $OUT_DIFF, '>', './difference.txt'; say $OUT_DIFF $_ for $lc->get_symmetric_difference; } my $duration = time - $start; say "Duration: $duration seconds.";
    However, on my small laptop (only 2 GByte RAM and running a lot of other programs and services) I get an "Out of memory" error, so two lists of 5 million proteins is too big for it. YMMV if you have a more performant machine. It runs fine and fast for 500,000 proteins (15 seconds), 1,000,000 proteins (52 seconds) and 2,000,000 proteins (185 seconds).

    CountZero

    A program should be light and agile, its subroutines connected like a string of pearls. The spirit and intent of the program should be retained throughout. There should be neither too little or too much, neither needless loops nor useless variables, neither lack of structure nor overwhelming rigidity." - The Tao of Programming, 4.1 - Geoffrey James

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