On Tue, 2006-11-28 at 16:20 -0500, Guenther, Cameron wrote: > Hi All, > > If you could help me with this problem I would greatly appreciate it. > > Suppose I have a matrix A: > > 1 1 1 1 0 1 1 1 1 > 1 1 1 0 1 0 1 0 0 > 1 0 1 0 0 1 0 0 0 > 1 1 0 0 0 0 1 0 0 > > I would like, for each row, to sum the number of times a 0 appears in > front of a 1. So what I would like is to have > Sum > 1 1 1 1 0 1 1 1 1 1 > 1 1 1 0 1 0 1 0 0 2 > 1 0 1 0 0 1 0 0 0 2 > 1 1 0 0 0 0 1 0 0 1 > > I tried writing a function to do this but am getting mixed up in the > [i,j] coding. This is just an example the real matrix is much larger. > > Thanks in advance.
Not fully tested, but how about this: > mat [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] 1 1 1 1 1 0 1 1 1 1 2 1 1 1 0 1 0 1 0 0 3 1 0 1 0 0 1 0 0 0 4 1 1 0 0 0 0 1 0 0 > cbind(mat, colSums(apply(mat, 1, diff) == 1)) [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10] 1 1 1 1 1 0 1 1 1 1 1 2 1 1 1 0 1 0 1 0 0 2 3 1 0 1 0 0 1 0 0 0 2 4 1 1 0 0 0 0 1 0 0 1 HTH, Marc Schwartz ______________________________________________ R-help@stat.math.ethz.ch 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.
