Thanks Henrique Here's what I came up with
temp<-read.table(filename, header=TRUE) tempm<-tapply(temp[,3],temp[,1:2],c) #put dataframe into matrix form tempm<-(tempm + t(tempm))/2 #add matrix to matrix flipped about diagonal and divide by 2 Bill On Wed, Dec 10, 2008 at 1:29 PM, Henrique Dallazuanna <[EMAIL PROTECTED]> wrote: > Try this: > > x$zMean <- ave(x$z, > apply(x[,1:2], 1, function(x)paste(sort(x), > collapse = "")), > FUN = mean) > > xtabs(zMean ~ x + y, data = x) > > > On Wed, Dec 10, 2008 at 11:16 AM, William Simpson > <[EMAIL PROTECTED]> wrote: >> >> On re-reading ?cmdscale I see that I can also use cmdscale(d) on a >> full matrix rather than just the lower triangle. >> d: a distance structure such as that returned by 'dist' or a >> full symmetric matrix containing the dissimilarities. >> >> So how to get a full symmetric matrix from a dataframe like this (toy >> example)? >> x y z >> "a" "a" 0 >> "a" "b" 1 >> "a" "c" 2 >> "b" "a" .9 >> "b" "b" 0 >> "b" "c" 1.3 >> "c" "a" 2.2 >> "c" "b" 1.1 >> "c" "c" 0 >> >> Replacing the corresponding cells in the matrix by their means, I need >> this: >> >> c 2.10 1.20 0.00 >> b 0.95 0.00 1.20 >> a 0.00 0.95 2.10 >> a b c >> >> E.g. in the original data, the cell (a,b) = 1; (b, a) =0.9. In the >> final matrix, (a,b) = (b,a) =0.95 >> >> Thanks very much for any help. >> >> Bill >> >> ______________________________________________ >> 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. > > > > -- > Henrique Dallazuanna > Curitiba-Paraná-Brasil > 25° 25' 40" S 49° 16' 22" O > ______________________________________________ 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.
