Is this what you were after: > mdat <- matrix(c(1,0,1,1,1,0), nrow = 2, ncol=3, byrow=TRUE, + dimnames = list(c("T1", "T2"), + c("sp.1", "sp.2", "sp.3"))) > > mdat sp.1 sp.2 sp.3 T1 1 0 1 T2 1 1 0 > # do 'rle' on each column and see if it is length >1 and starts with zero > mdat.df <- as.data.frame(mdat) > new.spec <- sapply(mdat.df, function(x){ + x.rle <- rle(x) + (length(x.rle$values) > 1) & (x.rle$values[1L] == 0) + }) > names(mdat.df)[new.spec] [1] "sp.2" >
On Wed, May 18, 2011 at 9:37 AM, Michael Denslow <michael.dens...@gmail.com> wrote: > Dear R help, > Apologies for the less than informative subject line. I will do my > best to describe my problem. > > Consider the following matrix: > > mdat <- matrix(c(1,0,1,1,1,0), nrow = 2, ncol=3, byrow=TRUE, > dimnames = list(c("T1", "T2"), > c("sp.1", "sp.2", "sp.3"))) > > mdat > > In my actual data I have time (rows) and species occurrences (0/1 > values, columns). I want to count the number of new species that occur > at a given time sample. For the matrix above the answer would be 1. > > Is there a simple way to figure out if the species has never occurred > before and then sum them up? > > Thanks in advance, > Micheal > > -- > Michael Denslow > > I.W. Carpenter Jr. Herbarium [BOON] > Department of Biology > Appalachian State University > Boone, North Carolina U.S.A. > -- AND -- > Communications Manager > Southeast Regional Network of Expertise and Collections > sernec.org > > 36.214177, -81.681480 +/- 3103 meters > > ______________________________________________ > 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. > -- Jim Holtman Data Munger Guru What is the problem that you are trying to solve? ______________________________________________ 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.