S+ has a few other traps when you are
dealing with large processing jobs.
One which I discovered is that S+ 7 for
windows has a limit of 1,000 objects in the Restore Data Objects. If you are
creating a new object in a chapter with each iteration then after 1,000 objects
S+ will dramatically slow down and basically grind to a halt, no matter how
small the objects are, and no matter how much RAM you have. Avoid this kind of
assignment. If you need to create new objects with each iteration then create a
list object with the required number of elements, and assign the objects to the
list instead.
This is all to do with the automatic Restore
Data Objects. If you create a brand
new chapter with undo specifically turned off it won’t do it, but as soon
as you re-open the chapter it starts restoring objects again.
Personally I don’t like the data
restore feature. Early versions of S+ didn’t have it, and you just got
used to saving scripts and backing up important objects (which is good
analysis/programming practice). When S+ became a “Windows”
application we got the undo and a pile of other useless features.
Michael
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MICHAEL CAMILLERI BSc, MSc, PhD
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BUILDING PHYSICIST
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PRIVATE BAG 50908
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PORIRUA CITY 5240
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WWW.BRANZ.CO.NZ
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From: Herschtal Alan
[mailto:Alan.Herschtal@petermac.org]
Sent: Monday, 4 June 2007 1:24
p.m.
To: s-news@lists.biostat.wustl.edu
Subject: Time management in S-Plus
I
am trying to run many iterations of a simulation in S-plus, and am finding that
the time taken per iteration increases almost exponentially. I have tried to
write the code as efficiently as I can, with minimal use of for loops, vector
arithmetic wherever possible, and reusing datasets where feasible. I understand
that this phenomenon has something to do with the paging in S-plus's memory
management system. Is there any way to keep the execution time constant ?
Thanks,
Alan Herschtal
Biostatistician
Centre for Biostatistics and Clinical
Trials
Peter MacCallum Cancer Centre
Ph: 9656 3639