Re: Re: lc entire contents of array?

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Re: Re: Re: lc entire contents of array? by dave_the_m (Monsignor) on Mar 30, 2004 at 22:43 UTC
What counts as newer versions? I find that map whups for's sorry ass in benchmarks under 5.8.0 and 5.8.2. Eh? `use Benchmark; @a = qw(the quick brown fox jumps over the lazy dog); timethese(1000000, { 'for' => '$_ = lc for @a', 'map' => '@a = map lc, @a', }); $ perl580 /tmp/p Benchmark: timing 1000000 iterations of for, map... for: 20 wallclock secs (19.28 usr + 0.02 sys = 19.30 CPU) @ 51 +813.47/s (n=1000000) map: 47 wallclock secs (47.85 usr + 0.02 sys = 47.87 CPU) @ 20 +889.91/s (n=1000000)` [download]	[reply] [d/l]
Re: Re: Re: Re: lc entire contents of array? by Willard B. Trophy (Hermit) on Mar 31, 2004 at 15:30 UTC
`$ ./dave_the_m.pl Benchmark: timing 1000000 iterations of for, map... for: 2 wallclock secs ( 2.03 usr + 0.00 sys = 2.03 CPU) @ 49 +2610.84/s (n=1000000) map: 1 wallclock secs ( 1.12 usr + 0.00 sys = 1.12 CPU) @ 89 +2857.14/s (n=1000000)` [download] That was Perl 5.8.0 on a P3-600. I got similar results on a Sparc box with 5.8.2. I rather think we might be benchmarking other things than just the `map` and the `for`. For instance, `lc`ing an array with 10,000 elements doesn't seem to take appreciably longer than one with 1,000 elements. Anyway, wiser monks have already pointed out that legibility should come first. Optimisation is a hardware problem. -- bowling trophy thieves, die!	[reply] [d/l] [select]
Re: Re: Re: lc entire contents of array? by Limbic~Region (Chancellor) on Mar 30, 2004 at 22:26 UTC
Willard B. Trophy, I think you assumed by efficient I meant faster. There are all kinds of ways to be efficient. Typically you trade memory for speed. As dragonchild points out, the map creates a temporary list. I say newer versions of Perl because older versions of Perl, it is my understanding, did the same thing in for loops. Cheers - L~R	[reply]