Re: [R] performance question
On Fri, 26 Sep 2003, Axel Benz wrote: > Hi, > I am about to write functions for multivariate kernel densitiy estimation > with mixed categorical and continuous date (accoring to Jeff Racine and Qi > Li), and the leave-one-out window esitmation needs a lot of computation. > I am now optimizing the code performance and therefore fhe following > questions: > > As R uses call-by-value for functions, is it computational expensive to pass > large matrices in function arguments? No, as long as they are not modified. R doesn't make actual copies if it knows they aren't needed, it just creates a reference to the original object. > (i.e. are they really copied and does this need much computing time?) Is it > maybe better to work with locally visible variables and nested functions in > the optimized code? It probably won't make a detectable difference. Looking up a variable is microscopically quicker if it is local (eg passed as a parameter), but you need fairly extreme cases for this to be noticeable. -thomas Thomas Lumley Assoc. Professor, Biostatistics [EMAIL PROTECTED] University of Washington, Seattle __ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
Re: [R] performance question
Axel - I believe that a function argument is not literally copied until the first time it is modified within the function. See email exchanges on this list from/to Ross Boylan within the month of September for a more authoritative answer to this question. (Do you know about the R-help archives at three sites listed on http://cran.R-project.org/search.html ?) - tom blackwell - u michigan medical school - ann arbor - On Fri, 26 Sep 2003, Axel Benz wrote: > I am about to write functions for multivariate kernel densitiy estimation > with mixed categorical and continuous date (accoring to Jeff Racine and Qi > Li), and the leave-one-out window esitmation needs a lot of computation. > I am now optimizing the code performance and therefore fhe following > questions: > > As R uses call-by-value for functions, is it computational expensive to pass > large matrices in function arguments? > > (i.e. are they really copied and does this need much computing time?) Is it > maybe better to work with locally visible variables and nested functions in > the optimized code? > > I have already used Rprof (and I could speed up the code a lot by the > information from Rprof), but it does not tell me about that. > > Thank you for your hints! > > Axel > > Fraunhofer Institut fuer > Arbeitswirtschaft und Organisation (IAO) > Dipl. Inf. Axel Benz > Nobelstr. 12 > D-70569 Stuttgart > Germany > Tel. +49(0)7119702289 > Fax. +49(0)7119702192 > mail: mailto:[EMAIL PROTECTED] > www: http://www.vis.iao.fhg.de > __ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
