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Re^3: Splicing Arrays on pre-defined indices

by ikegami (Pope)
on Jun 28, 2008 at 14:29 UTC ( #694518=note: print w/replies, xml ) Need Help??

in reply to Re^2: Splicing Arrays on pre-defined indices
in thread Splicing Arrays on pre-defined indices

my @exclude = (2,5..8); my @exclude_lkup; $exclude_lkup[$_] = 1 for @exclude; my $line = "1!2!3!4!5!6!7!8!9"; my @arr = split /!/, $line; my @filtered = map $arr[$_], grep !$exclude_lkup[$_], 0..$#arr; print("@filtered\n"); # 1 2 4 5

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Re^4: Splicing Arrays on pre-defined indices
by harishnuti (Beadle) on Jun 28, 2008 at 15:27 UTC
    This is awesome, this is what iam looking for....Thx a lot.
Re^4: Splicing Arrays on pre-defined indices
by injunjoel (Priest) on Aug 15, 2008 at 23:55 UTC
    Since I just updated my previous suggestion I figured I would Benchmark things...
    Not that it matters but I thought you might be interested.
    Update There was an issue with how I ran the test before. Here are the updated code and results.
    #!/usr/bin/perl -w use strict; use Benchmark; my $count = 500000; my $line = "1!2!3!4!5!6!7!8!9"; my @arr = split /!/, $line; my @exclude = (2,5..8); my @exclude_lkup; $exclude_lkup[$_] = 1 for @exclude; sub ikegami { my @tarr = @arr; my @filtered = map $tarr[$_], grep !$exclude_lkup[$_], 0..$#tarr; } sub injun { my @tarr = @arr; @tarr[@exclude] = (); @tarr = grep $_, @tarr; } timethese ( $count, {'Ikegami' => '&ikegami', 'InjunJoel' => '&injun'} );
    Results in
    Benchmark: timing 500000 iterations of Ikegami, InjunJoel... Ikegami: 16 wallclock secs (15.88 usr + 0.00 sys = 15.88 CPU) @ 314 +94.08/s (n=500000) InjunJoel: 10 wallclock secs ( 11.05 usr + 0.00 sys = 11.05 CPU) @ 4 +5265.25/s (n=500000)
    Though I'm not versed enough in O(n) notation to tell you why...

    "I do not feel obliged to believe that the same God who endowed us with sense, reason and intellect has intended us to forego their use." -Galileo

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