The original post said the matrices are symmetric but it seems from the examples that they are not symmetric but do each have the same row and column names so we have assumed only this latter condition instead.
If your matrices are called big and small then: ix <- rownames(big) %in% rownames(small) result <- big result[ix, ix] <- big[ix, ix] + small Also in the example every row name in small is also a row name in big so if that is true in general then the first line above could be just: ix <- rownames(small) In the future please display the output dput in your post to make it easier to reproduce your data, e.g. dput(big) On Fri, Mar 19, 2010 at 9:51 PM, duncandonutz <dwads...@unm.edu> wrote: > > To clarify, the two matrices might look like this: > > A B C D E F > A 1 2 3 4 5 6 > B 2 4 6 8 10 12 > C 0 0 0 0 0 0 > D 0 1 0 1 0 1 > E 3 6 9 11 13 15 > F 2 2 2 2 2 2 > > B D E > B 4 9 13 > D 9 8 7 > E 1 0 1 > > I would like this: > > A B C D E F > A 1 2 3 4 5 6 > B 2 8 6 17 23 12 > C 0 0 0 0 0 0 > D 0 10 0 9 7 1 > E 3 7 9 11 14 15 > F 2 2 2 2 2 2 > > Thanks. > -- > View this message in context: > http://n4.nabble.com/Merging-Matrices-tp1605474p1636943.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > 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.
