Re^3: promoting array to a hash

very important update: Please see Re^4: promoting array to a hash by BrowserUk for why the following code is horrifically wrong. Of course, that said, it requires one very simple s!my!our! to correct.

I know that the map vs. slice benchmark has been done before, but just to do it again as a reminder :)

#!perl -w

use strict;
use Benchmark ':all';

my @unsorted = map {
    join('', map { ('a'..'z','A'..'Z',0..9)[rand 62] } 1..50)
} 1..5000;

sub uniq_dragonchild { my %x; @x{@_} = @_; values %x }
sub uniq_BrowserUk { my %x; @x{@_} = (); keys %x }
sub uniq_Zaxo { keys %{ { map { $_ => undef } @_ } } }

cmpthese(
    timethese(-60, {
        uniq_dragonchild => 'my @x = uniq_dragonchild(@unsorted)',
        uniq_BrowserUk   => 'my @x = uniq_BrowserUk(@unsorted)',
        uniq_Zaxo        => 'my @x = uniq_Zaxo(@unsorted)'
    } )
);

__END__
C:\>uniq.pl
Benchmark: running uniq_BrowserUk, uniq_Zaxo, uniq_dragonchild for at 
+least 60 C
PU seconds...
uniq_BrowserUk: 64 wallclock secs (63.19 usr +  0.02 sys = 63.20 CPU) 
+@ 421025.4
1/s (n=26610069)
 uniq_Zaxo: 59 wallclock secs (60.08 usr +  0.03 sys = 60.11 CPU) @ 18
+6939.31/s
(n=11237109)
uniq_dragonchild: 64 wallclock secs (63.05 usr +  0.02 sys = 63.06 CPU
+) @ 399674
.64/s (n=25204682)
                     Rate        uniq_Zaxo uniq_dragonchild   uniq_Bro
+wserUk
uniq_Zaxo        186939/s               --             -53%           
+  -56%
uniq_dragonchild 399675/s             114%               --           
+   -5%
uniq_BrowserUk   421025/s             125%               5%           
+    --
[download]

Comment on Re^3: promoting array to a hash Select or Download Code

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Re^4: promoting array to a hash by Roy Johnson (Monsignor) on Jun 13, 2004 at 13:58 UTC
Adding this sub: `sub uniq_Roy { my %x; grep {!$x{$_}++} @_ }` [download] I got these results `Rate uniq_Zaxo uniq_dragonchild uniq_BrowserUk + uniq_Roy uniq_Zaxo 167192/s -- -19% -27% + -47% uniq_dragonchild 205487/s 23% -- -11% + -35% uniq_BrowserUk 230383/s 38% 12% -- + -27% uniq_Roy 317586/s 90% 55% 38% + --` [download] We're not really tightening our belts, it just feels that way because we're getting fatter.	[reply] [d/l] [select]
Re^5: promoting array to a hash by dragonchild (Archbishop) on Jun 14, 2004 at 01:35 UTC
Excellent! Yours is faster and will DWIM with references. Good deal! :-) ------ We are the carpenters and bricklayers of the Information Age. Then there are Damian modules.... sigh* ... that's not about being less-lazy -- that's about being on some really good drugs -- you know, there is no spoon.* - flyingmoose I shouldn't have to say this, but any code, unless otherwise stated, is untested	[reply]
Re^5: promoting array to a hash by BrowserUk (Patriarch) on Jun 14, 2004 at 12:02 UTC
Unfortunately, the benchmark you started with wasn't good. See Re^4: promoting array to a hash. Examine what is said, not who speaks. "Efficiency is intelligent laziness." -David Dunham "Think for yourself!" - Abigail	[reply]
Re^4: promoting array to a hash by BrowserUk (Patriarch) on Jun 14, 2004 at 11:59 UTC
Unfortunately, your benchmark is wrong. As the array `@unsorted` is lexical, it isn't visible within the benchmark code, so the subs are uniquifying an empty array. All your benchmark is measuring is how quickly the sub return nothing. Correcting that, I get these results. #!perl -w use strict; use Benchmark ':all'; our @unsorted = map { join('', map { ('a'..'z','A'..'Z',0..9)[rand 62] } 1..50) } 1..5000; sub uniq_dragonchild { my %x; @x{@_} = @_; values %x } sub uniq_BrowserUk { my %x; @x{@_} = (); keys %x } sub uniq_Zaxo { keys %{ { map { $_ => undef } @_ } } } sub uniq_Roy { my %x; grep {!$x{$_}++} @_ } our( @a, @b, @c, @d ); cmpthese( -1, { uniq_dragonchild => '@a = uniq_dragonchild( @unsorted )', uniq_BrowserUk => '@b = uniq_BrowserUk( @unsorted )', uniq_Zaxo => '@c = uniq_Zaxo(@unsorted)', uniq_Roy => '@d = uniq_Roy( @unsorted )', }); #my $a='a'; print $/, $a++, ' : ', "@{[ sort @$_ ]}" for ( \@a, \@b, \ +@c, \@d ); __END__ P:\test>363760 Rate uniq_dragonchild uniq_Zaxo uniq_Roy uniq +_BrowserUk uniq_dragonchild 18.1/s -- -21% -31% + -41% uniq_Zaxo 22.8/s 26% -- -13% + -25% uniq_Roy 26.3/s 45% 15% -- + -14% uniq_BrowserUk 30.6/s 69% 34% 16% + -- [download] Examine what is said, not who speaks. "Efficiency is intelligent laziness." -David Dunham "Think for yourself!" - Abigail	[reply] [d/l] [select]
Re^5: promoting array to a hash by saskaqueer (Friar) on Jun 15, 2004 at 05:30 UTC
Oh ouch, that bit me good. I can't believe I didn't find 420000+ iterations per second too many, considering it is handling a 5000 item list. Thanks BrowserUk (and obviously ++).	[reply]