Re: Re: Re: Array sort

True, he could have it written it in such a way to minimize a bunch of the minor overheads of the loop construct.

Thus

my $min_i = 0;
foreach my $i (1..$#array) {
  $min_i = $i if $array[$i]->[2] < $array[$min_i]->[2];
}
[download]

becomes

my $index=0;
$array[$_][2]<$array[$index][2] && ($index=$_)
   foreach 1..$#array;
[download]

But I'm so sure its easier to understand...

;-)

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Re: Re: Re: Re: Array sort - kind of... by petral (Curate) on Feb 04, 2002 at 20:47 UTC
Wouldn't this eliminate more of the overhead? `my ($min, $min_i) = ($array[0]->[2], 0); foreach my $i (1..$#array) { ($min, $min_i) = ($array[$i]->[2], $i) if $array[$i]->[2] < $min; }` [download] p	[reply] [d/l]
Re: x 5 Array sort - kind of... (benchmark) by demerphq (Chancellor) on Feb 05, 2002 at 10:25 UTC
Yup, sure does. (sigh busted ;-) But it turns out a combination is slightly better as well. The modifier form of the for loop doesn't have the marginal overhead of scope (er I think...), although I wonder if the 3% gain is worth the obfu. I have to admit that I was suprised to discover that the list assignment is so much faster than an array lookup (which obviously is why yours is faster). Somthing I shall keep in mind for the future. Heres my benchmarks... `Benchmark: running demerphq, petral, petral_modifier, each for at leas +t 60 CPU seconds... demerphq: 66 wallclock secs (62.98 usr + 0.00 sys = 62.98 CPU) @ 21 +2.26/s (n=13369) petral: 64 wallclock secs (62.99 usr + 0.00 sys = 62.99 CPU) @ 26 +7.17/s (n=16828) petral_modifier: 64 wallclock secs (63.17 usr + 0.00 sys = 63.17 CPU) + @ 274.43/s (n=17336) Rate demerphq petral petral_modifier demerphq 212/s -- -21% -23% petral 267/s 26% -- -3% petral_modifier 274/s 29% 3% --` [download] Yves / DeMerphq -- When to use Prototypes?	[reply] [d/l]


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