Use the Matrix package which provides easy access to sparse matrices. I think (unchecked) there's even easy provision for a diagonal sparse matrix.
That said, if you are always working with diagonal matrices, couldn't you just keep the diagonals as vectors since the formulas for matrix multiplication reduce nicely in that case? Michael On Mon, Feb 6, 2012 at 6:10 AM, Alaios <ala...@yahoo.com> wrote: > Thanks a lot for your answer :) > actually I am converting a 256*256 image to a vector so to apply some 1-d > transformations. Is it possible to create in R a sparse matrix instead of > carrying all those zeros? > > So that means that I want to have a diagonal sparse matrix.. > > Thanks a lot > > Alex > > > ________________________________ > From: peter dalgaard <pda...@gmail.com> > > Cc: "R-help@r-project.org" <R-help@r-project.org> > Sent: Monday, February 6, 2012 11:54 AM > Subject: Re: [R] R's memory capabilities > > > On Feb 6, 2012, at 11:15 , Alaios wrote: > >> Dear all, >> I have tried to create a diagonal matrix of size diag(65536) >> >> I am getting the message that the array function can not create so big array >> as the value I ask is larger than the >> >> >> <environment: namespace:base> >>> .Machine$integer >> [1] 2147483647 >> >> >> as you will see my .Machine$integer is the one above. What that variable >> means? I am using R in a system that has 500 GB of ram available. Would it >> be something wrong in the installation? > > Well, it means what it says. Indexing is limited by the size of a 32-bit > integer and (2^16)^2 is too big for that. So you are limited to roughly 16 GB > for any single object in R. > > This issue has been foreseeable for some time. It can only be fixed by > internal changes in the R engine, but switching to long integers has various > issues, so it is not a straightforward modification. > > Meanwhile, you might want to consider whether you really do need a diagonal > matrix of that size stored in full. It's an awful lot of zeroes to carry > around.... > >> >> Regards >> Alex >> >> [[alternative HTML version deleted]] >> >> ______________________________________________ >> 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. > > -- > Peter Dalgaard, Professor > Center for Statistics, Copenhagen Business School > Solbjerg Plads 3, 2000 Frederiksberg, Denmark > Phone: (+45)38153501 > Email: pd....@cbs.dk Priv: pda...@gmail.com > [[alternative HTML version deleted]] > > > ______________________________________________ > 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.
