On Tue, May 24, 2005 at 02:13:49PM -0400, Dave Gray wrote:
> On 5/23/05, Peter Rabbitson <[EMAIL PROTECTED]> wrote:
> > On Mon, May 23, 2005 at 01:40:08PM -0400, Zhenhai Duan wrote:
> > > I tried hash (where the members of a group are joined with ":"), and hash
> > > of hash. It happended that hash of hash is slower than single hash.
> > >
> > > Hash:
> > > $groups{$g1} = "$member1:$member2";
> > >
> > > Hash of hash
> > > $groups{$g1}{$member1} = 1;
> > >
> > > Method 1 is faster, even I need to do a split to get the members.
> >
> > Can you post some code? Without it the above statement is not very credible
> > to say the least.
>
> The 1D approach seems to be approximately 3 times as fast (on x86
> Linux). Anyone get different results?
>
> #!/usr/bin/perl
> use strict;
> use warnings;
>
> my @ra = ('a' .. 'z', 'A' .. 'Z');
> my ($seqlen, $hashsize) = (4, 70000);
>
> my (%oned, %twod) = ((),());
> my (@l1, @l2) = ((),());
>
> $|++;
> print "generating hashes";
> for my $i (1 .. $hashsize) {
> my $key1 = join('', @ra[map(int(rand($#ra))+1, 1 .. $seqlen)]);
> push @l1, $key1;
> my $key2 = join('', @ra[map(int(rand($#ra))+1, 1 .. $seqlen)]);
> push @l2, $key2;
> $oned{"$key1:$key2"}++;
> $twod{$key1}{$key2}++;
> print '.' if not $i % int($hashsize/10);
> }
> print "!\n";
>
> # baseline
> my ($su, $ss) = times;
> for (1 .. $hashsize) { }
> my ($eu, $es) = times;
> my ($tu, $ts) = ($eu - $su, $es - $ss);
> my $tt = $tu + $ts;
> printf "%20s %5.2f %5.2f %6.2f\n", 'base', $tu, $ts, $tt;
>
> # access test for 1d
> ($su, $ss) = times;
> for my $i (0 .. $hashsize-1) {
> $oned{"$l1[$i]:$l2[$i]"}++
> }
> ($eu, $es) = times;
> ($tu, $ts) = ($eu - $su, $es - $ss);
> $tt = $tu + $ts;
> printf "%20s %5.2f %5.2f %6.2f\n", '1D', $tu, $ts, $tt;
>
> # access test for 2d
> ($su, $ss) = times;
> for my $i (0 .. $hashsize-1) {
> $oned{$l1[$i]}{$l2[$i]}++
I think you should be operating on %twod here.
> }
> ($eu, $es) = times;
> ($tu, $ts) = ($eu - $su, $es - $ss);
> $tt = $tu + $ts;
> printf "%20s %5.2f %5.2f %6.2f\n", '2D', $tu, $ts, $tt;
But your real gains will come when you want to do something which does
not require iterating through all the elements you have created.
--
Paul Johnson - [EMAIL PROTECTED]
http://www.pjcj.net
--
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
<http://learn.perl.org/> <http://learn.perl.org/first-response>
