| How to speed up large FOR loops? [message #79814] |
Tue, 10 April 2012 08:48  |
Saurav Dhital
Messages: 4
Registered: April 2012
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Junior Member |
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Hi,
By necessity, I have to use a long FOR loop (N >~ 300,000). I have
made the operations inside the loop efficient enough that the first
40,000 iterations are relatively fast (~30 mins). Then it slows down
to a crawl, with the entire process taking >24 hours. I would
appreciate any advice how to speed this up.
The operation inside the loop involves matching between two (large)
FITS files and assigning the matches to another (previously created)
FITS structure. There are no new variable created per iteration, so
there should be no memory being used (each loop writes over the
variables anyways). I even create small substructures (e.g., >
sub_mystruct = mystruct[0:10]) so that I don't have to index the large
structures.
Any tip or advice would be much appreciated,
~Saurav
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| Re: How to speed up large FOR loops? [message #79980 is a reply to message #79814] |
Fri, 20 April 2012 09:53  |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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Saurav writes:
> Thanks! I will use th profiler, probably David's as I already use a
> lot of his code.
David doesn't have a profiler. He still uses friggin' Print
statements like all the other old fogies I know. :-(
Cheers,
Coyote
--
Coyote, R.N, USMC
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")
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