Yoav - Here's one possibility:
wh = outer(rownames(mtrx),colnames(mtrx),
+ function(x,y)substr(x,nchar(x)-2,nchar(x)) == substr(y,nchar(y)-2,nchar(y)))
mtrx[wh]
[1] 1 6 8
If you knew that all of the row and column names were 4 characters long, it would simplify to
mtrx[outer(rownames(mtrx),colnames(mtrx),function(x,y)substr(x,2,4) == substr(y,2,4))]
Hope this helps. - Phil Spector Statistical Computing Facility Department of Statistics UC Berkeley spec...@stat.berkeley.edu On Wed, 20 Apr 2011, yoav baranan wrote:
Hi, I have a (correlation) matrix and I want to select a subset of its cells depending on the combination of their column and row names. This illustrates my problem: mtrx <- matrix(c(1,2,3,4,5,6,7,8,9), nrow=3, ncol=3, dimnames = list(c('c132','c432', 'c233'), c('r132','r233', 'r432')))> mtrx r132 r233 r432c132 1 4 7c432 2 5 8c233 3 6 9 At this point I want to compute the mean of the cells in which the column and the row names share the same suffix (i.e., the cells mtrx[1,1], mtrx[2,3], mtrx[3,2]). By suffix I mean the last three digits of the row/col name. I need a generic code (and not vec<-c(mtrx[1,1], mtrx[2,3], mtrx[3,2])) because I don't know in advance how many rows and columns I will have (currently 118). Thanks, Yoav [[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.