I wouldn't assume R is making a copy; it depends on what you're doing with the dataframe.

I'd suggest using Rprof to find out where the cpu time is being spent. If you can adapt your problem to use all numbers or all characters then you can store the data in a matrix instead of a data frame, and potentially speed things up. (That advice is based on my own experience from a fairly large number of years ago, so it's possible that developments in R since then could negate the advice.)

-Don

At 4:38 PM -0700 9/18/09, Mark Knecht wrote:
Hi,
   Is there a way to pass the address of a data.frame through a set of
functions in R? I've got some code which is slowing down I think
because my data.frames are getting much larger - now approaching 1
million rows by 50-100 columns - and my functions - originally written
for much smaller data elements are sampling these data.frames a couple
of layers down.

   Before I rewrite them to do the sampling at the top level if there
was a way to pass the address of the data.frame instead of the a copy
of the whole thing then I suspect that would speed things up
significantly.

Thanks,
Mark

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--
--------------------------------------
Don MacQueen
Environmental Protection Department
Lawrence Livermore National Laboratory
Livermore, CA, USA
925-423-1062

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