Re: Mysterious slow down with large data set

I can't see what is causing the slowdown, but I can see one obvious thing that would speed it up a lot. You keep re-sorting the keys to %kernel every time when they do not change. Instead of:

foreach $w1 ( sort( keys %kernel ) ){
    $totalsim = $maxsim = 0;
    @topX = ();
    $at2 = 0;

    foreach $w2 ( sort( keys %kernel ) ) { 
...
[download]

Using:

my @sortedKeys = sort( keys %kernel );
foreach $w1 ( @sortedKeys ){
    $totalsim = $maxsim = 0;
    @topX = ();
    $at2 = 0;

    foreach $w2 ( @sortedKeys ) {
[download]

may speed things up to the point that the slowdown becomes insignificant.

Also, using a sort to track top N is probably slower than a simple linear insertion and truncate if necessary.

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority".

In the absence of evidence, opinion is indistinguishable from prejudice.

The start of some sanity?

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Re^2: Mysterious slow down with large data set by jsmagnuson (Acolyte) on Feb 26, 2012 at 23:44 UTC
Yes, I can't believe I did that. Thank you! Regarding the top N, I had previously tried this, which worked, but seemed more complicated. Is this what you had in mind? `} elsif ($sim > min(pdl(@topList))) { $theMin = grep { $topX[$_] eq min(pdl(@topX)) } 0..$#topX; # replace the smallest $topX[$theMin] = $sim; # add this one push @topX, $sim; }` [download] Thanks!	[reply] [d/l]
Re^3: Mysterious slow down with large data set by BrowserUk (Patriarch) on Feb 27, 2012 at 00:22 UTC
I tried it this way: `@topX = (-1) x 20; ... $topX[ $_ ] < $sim and splice( @topX, $_, 0, $sim ), pop( @top +X ), last for 0 .. 19;` [download] A short-ciruited, linear insertion is at worst O(N) rather than O(N logN). It speeds things a little, but doesn't address the slowdown which is happening exclusively (and inexplicably) inside PDL. Unfortunately, the PDL documentation spends more time telling you about their 'philosophy'; and indexing the indexes to the documentation than is does telling you what these functions actually do; or how to inspect the results of what they did :( With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday' Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice. The start of some sanity?	[reply] [d/l]


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