Re^2: promoting array to a hash

Replies are listed 'Best First'.
Re^3: promoting array to a hash by saskaqueer (Friar) on Jun 13, 2004 at 08:02 UTC
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 { $_ => undef } @_ } } } cmpthese( timethese(-60, { uniq_dragonchild => 'my @x = uniq_dragonchild(@unsorted)', uniq_BrowserUk => 'my @x = uniq_BrowserUk(@unsorted)', uniq_Zaxo => 'my @x = uniq_Zaxo(@unsorted)' } ) ); __END__ C:\>uniq.pl Benchmark: running uniq_BrowserUk, uniq_Zaxo, uniq_dragonchild for at +least 60 C PU seconds... uniq_BrowserUk: 64 wallclock secs (63.19 usr + 0.02 sys = 63.20 CPU) +@ 421025.4 1/s (n=26610069) uniq_Zaxo: 59 wallclock secs (60.08 usr + 0.03 sys = 60.11 CPU) @ 18 +6939.31/s (n=11237109) uniq_dragonchild: 64 wallclock secs (63.05 usr + 0.02 sys = 63.06 CPU +) @ 399674 .64/s (n=25204682) Rate uniq_Zaxo uniq_dragonchild uniq_Bro +wserUk uniq_Zaxo 186939/s -- -53% + -56% uniq_dragonchild 399675/s 114% -- + -5% uniq_BrowserUk 421025/s 125% 5% + -- [download]	[reply] [d/l] [select]
Re^4: promoting array to a hash by Roy Johnson (Monsignor) on Jun 13, 2004 at 13:58 UTC
Adding this sub: `sub uniq_Roy { my %x; grep {!$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]
Re^3: promoting array to a hash by dragonchild (Archbishop) on Jun 14, 2004 at 01:30 UTC
It will be slightly quicker. However, it is of less use. My version will DWIM references while yours won't. ------ 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^4: promoting array to a hash by BrowserUk (Patriarch) on Jun 14, 2004 at 06:03 UTC
Finding unique references and then sorting them huh? Examine what is said, not who speaks. "Efficiency is intelligent laziness." -David Dunham "Think for yourself!" - Abigail	[reply]
Re^5: promoting array to a hash by dragonchild (Archbishop) on Jun 14, 2004 at 11:25 UTC
Who said anything about sorting them? And, this has been very useful when dealing with lists of singletons. :-) ------ 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^6: promoting array to a hash by BrowserUk (Patriarch) on Jun 14, 2004 at 11:51 UTC