assigning rownames (after the object is created) triggers a copy of the object... if you assign the rownames at creation time, no extra copies...
b On Mon, Feb 22, 2010 at 9:46 AM, Larson, TR <t...@york.ac.uk> wrote: > Hi, > > On R 2.10.1 for Windows, when I do the following to duplicate the structure > of a large numeric matrix called matrix1: > > matrix2 <- matrix(0,nrow=nrow(matrix1),ncol=ncol(matrix1)) > > and then > > rownames(matrix2) <- rownames(matrix1) > > I get a "cannot allocate vector of size xxMb" error > > but if I instead do: > > rnames <- list() > rnames <- rownames(matrix1) > matrix2 <- matrix(0,nrow=nrow(matrix1),ncol=ncol(matrix1),dimnames=rnames) > > I get no error. > > Of course both approaches work in R on Unix without memory limits. But I'm > intrigued about the apaprent difference in memory usage/allocation for the > two above approaches. Is there any explanation for this difference in > behaviour? > > thanks > Tony > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
