That would be great. We'll need to be able to reproduce the problem before we can fix it.
Thanks, Chris On Thu, Feb 2, 2012 at 4:50 PM, Adam Russell <[email protected]> wrote: > I am using pdl 2.4.9. > In both cases the data was initialized the exact same way. > This is part of a much larger body of code but if you'd like for me to do so > I can try > and create a small test case to replicate this behavior. > >> Date: Thu, 2 Feb 2012 12:49:24 -0500 > >> Subject: Re: [Perldl] how to sort a piddle ??? >> From: [email protected] >> To: [email protected] >> CC: [email protected] > >> >> If ->at() works but ->sclr doesn't that would suggest >> a problem. What version of PDL are you running? >> Is it possible that @t_stats was initialized to piddle >> values for the slow case. at and sclr should give >> the same results.... >> >> --Chris >> >> On Thu, Feb 2, 2012 at 12:24 PM, Adam Russell <[email protected]> wrote: >> > Well, the docs >> > http://pdl.perl.org/PDLdocs/Core.html#sclr >> > state "The sclr method is useful to turn a piddle into a normal Perl >> > scalar." >> > If at works and sclr doesn't than maybe something is wrong with the sclr >> > code? >> > The docs say they should have the same output with the convenience that >> > sclr >> > doesn't require you to specify a position. >> > So, lets see what happens when I use at... >> > Ok, I now see this in the profiler output >> > >> > @s_t_stats=sort {$b <=> $a} @t_stats; >> > # spent 3.92ms making 4 calls to CORE:sort, avg >> > 980µs/call >> > So, ok, at wins! >> > Thanks for the advice! >> > Finally though, does this indicate a problem with sclr? >> > >> > ________________________________ >> > Date: Thu, 2 Feb 2012 10:31:53 -0600 >> > >> > Subject: Re: [Perldl] how to sort a piddle ??? >> > From: [email protected] >> > To: [email protected] >> > CC: [email protected] >> > >> > >> > Hmm, looks to me like "sclr" may not be doing what you mean. I'm not >> > sure, >> > though, because I've never noticed sclr before. At any rate, it looks >> > like >> > the sort is calling the spaceship operator on piddles, but it should be >> > using the built-in spaceship operator because it should be sorting >> > scalars. >> > >> > What happens to your sort if you use "at" instead of "sclr"? >> > >> > David >> > >> > On Thu, Feb 2, 2012 at 10:01 AM, Adam Russell <[email protected]> >> > wrote: >> > >> > This thread reminded me of a pdl sort issue I was having. >> > I hope I not too off topic... >> > So, I am using pdl from within a larger body of Perl code. >> > I am using PDL::Stats to perform a t_test on a bunch of data I store in >> > pdls. >> > Once I get done with this I sort the t-statistics and then throw away >> > the >> > pdls. >> > I noticed my code was running somewhat slower than I would have thought >> > it >> > shoud. >> > So, I ran the code under the NYT profiler. My code was spending the >> > majority >> > of its time (~80% of total execution time!) >> > on the last line below(yeah, I uncreatively named the pdls "pdls"): >> > >> > foreach my $dim_n (0..$self->{dimension}-1){ >> > my ($t, $df) = t_test($pdls[$dim_n][$cat_n][0], >> > $pdls[$dim_n][$cat_n][1]); >> > $t_stats[$dim_n]=$t->abs->sclr; >> > } >> > @s_t_stats=sort {$b <=> $a} @t_stats; >> > >> > Here is what profiler output for that line looks like: >> > @s_t_stats=sort {$b <=> $a} @t_stats; >> > # spent 5.18s making 4 calls to CORE:sort, avg 1.29s/call >> > # spent 3.43s making 91451 calls to PDL::string, avg 38µs/call >> > # spent 939ms making 91451 calls to PDL::spaceship, avg >> > 10µs/call >> > # spent 44µs making 15 calls to PDL::DESTROY, avg 3µs/call >> > >> > 1.29 seconds for each call to sort is very long time! From the calls >> > made >> > when that line is executed it seems that for some reason >> > it is doing some sort of string conversion? But why? Surely >> > $t->abs->sclr is >> > returning a numeric, right? >> > The code currently takes about 10 seconds to run. If I take care of this >> > sort problem I could probably get runs in >> > under 3 seconds. >> > >> > Any advice on why this sort is so slow? >> > Best Regards, >> > Adam >> > >> > >> >> Date: Thu, 2 Feb 2012 07:07:24 -0600 >> >> From: [email protected] >> >> To: [email protected] >> >> CC: [email protected] >> >> Subject: Re: [Perldl] how to sort a piddle ??? >> > >> >> >> >> I agree with Matt that you are probably looking for `qsort`. >> >> >> >> As to what >> >> >> >> @e = pdl(3,2,6,4,8,6); >> >> @r = sort{$a <=> $b} @e; >> >> >> >> is doing, its working perfectly; its just not doing what you mean. @e >> >> is a one element Perl-level array, its one element is a PDL object. >> >> Any sort on a one element array will return the same order, what else >> >> could it do. >> >> >> >> You have to remember that a PDL object is just another scalar in >> >> Perl's eyes, as are all objects. >> >> >> >> Here is another example >> >> >> >> @e = (pdl(3,2,6,4,8,6), pdl(5,6,2,1)); >> >> @r = sort{$a <=> $b} @e; >> >> >> >> Here @e has two PDL object. When you sort objects numerically ( using >> >> <=> ), what you will actually sort on is not their contents, but their >> >> address in memory. >> >> >> >> The take-away message is this: PDL overloads many of the Perl >> >> operators, and it can feel like PDL and Perl are fully integrated, but >> >> in truth a PDL object is still an object, that is a scalar reference >> >> with methods and overloads. PDL tries to Do What You Mean when it can, >> >> this is not one of those times. >> > >> > >> > _______________________________________________ >> > Perldl mailing list >> > [email protected] >> > http://mailman.jach.hawaii.edu/mailman/listinfo/perldl >> > >> > >> > >> > >> > -- >> > "Debugging is twice as hard as writing the code in the first place. >> > Therefore, if you write the code as cleverly as possible, you are, >> > by definition, not smart enough to debug it." -- Brian Kernighan >> > >> > >> > _______________________________________________ >> > Perldl mailing list >> > [email protected] >> > http://mailman.jach.hawaii.edu/mailman/listinfo/perldl >> > > > _______________________________________________ > Perldl mailing list > [email protected] > http://mailman.jach.hawaii.edu/mailman/listinfo/perldl > _______________________________________________ Perldl mailing list [email protected] http://mailman.jach.hawaii.edu/mailman/listinfo/perldl
