Hi Peter, Thanks for your quick response. I am working with a dataframe that has columns of Year, Location, Type (pertains to type of location), Species, and Presence/Absence. What I'm interested in doing is generating a data frame that would not lose the "Year" , "Location" and "Type" data. I would ultimately like it to have the columns: "Year", "Location", "Type", "SpeciesA", "SpeciesB", and "Co-occurance", where Co-occurance is either a 0 or 1 for if the species co-occur at the particular location at that exact particular point in time.
Is there a function that exists out there that could quickly convert my data into this form? Or do I have to generate my own? Thanks! Lanna 2010/3/12 Peter Solymos <soly...@ualberta.ca> > Lanna, > > I don't know exactly what do you mean by co-occurrence data frame, but > if you'd like to get a species-by-species matrix, in which you count > the co-occurrences of the species (columns in the sites-by-species > community matrix) with each other, you can use the crossprod function > or the %*% operator for a presence/absence matrix: > > m <- matrix(rbinom(15,1,0.6),5,3) > t(m) %*% m > crossprod(m, m) > > HTH, > > Peter > > > On Fri, Mar 12, 2010 at 7:22 AM, Lanna Jin <lanna...@gmail.com> wrote: > > Hello All, > > > > I've been sifting through tons of R Documentation, trying to find a > command > > that converts a community matrix dataset into a species pair co-occurance > > data frame, and have failed miserably to find one. Does a function > already > > exist in one of the community analysis packages? > > > > Thanks in advance for your response! > > > > -- > > Lanna Jin > > > > lanna...@gmail.com > > 510-898-8525 > > > > [[alternative HTML version deleted]] > > > > _______________________________________________ > > R-sig-ecology mailing list > > R-sig-ecology@r-project.org > > https://stat.ethz.ch/mailman/listinfo/r-sig-ecology > > > > > -- Lanna Jin lanna...@gmail.com 510-898-8525 [[alternative HTML version deleted]] _______________________________________________ R-sig-ecology mailing list R-sig-ecology@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-ecology
