Thanks, David. This works splendidly. Thanks for your help. Sincerely, Brian
>>> David Winsemius <dwinsem...@comcast.net> 03/26/11 3:06 PM >>> On Mar 26, 2011, at 9:44 AM, Brian Pellerin wrote: > Hello, > > I would like to take advantage of the upper.tri() function here but > I don't > know exactly. Here is some working code... > i<-5 > fi<-matrix(0,nrow=i,ncol=i) > for(r in 1:i){ > for(c in 1:i){ > if(r==c){ > fi[r,c]<-1 > }else if(r<c){ > fi[r,c]<-1-runif(1)^.5 > }else{ > fi[r,c]<-fi[c,r] > } > } > } > > So far I know I can simplify this code to 5 lines (no for loops): > i<-5 > fi<-matrix(nrow=i,ncol=i) > fi[upper.tri(fi)]<-1-runif(length(fi[upper.tri(fi)]))^.5 > diag(fi)<-1 > fi[lower.tri(fi)]<-fi[upper.tri(fi)]#This entry is not correct. > fi[r,c] ! == > fi[c,r] I've always found using the upper.tri and lower.tri functions error prone in my hands, because they are really logical matrices for selection rather than returning values as I naively expect. Try this: i<-5 fi<-diag(1,i,i) fi[upper.tri(fi)]<-1-runif(length(fi[upper.tri(fi)]))^.5 fi[lower.tri(fi)]<-t(fi)[lower.tri(fi)] fi It may seem odd to use lower.tri(fi) inside `[ ]` since the values of `fi` in the lower triangle are all zero, but you are really just using it to extract from `t(fi)`. -- David. > > Any suggestions? > > Sincerely, > Brian > > [[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. David Winsemius, MD West Hartford, CT ______________________________________________ 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.