On Wednesday 20 August 2008, Josh B wrote: > > Works for me: > > x <- read.csv('christina.txt') > > > > x.list <- by(x, x$gen, function(d) { > > d.clean <- d[,-1] > > cov(d.clean, y= NULL, use= "complete.obs", method="pearson") > > } ) > > > >note that the output is a list, where each element corresponds to one > >level of 'gen'. if you need to write each element out to a file, see > >?sapply or ?lapply . > > Yes, how would I do that? The usage of sapply is pretty hard to understand, > at least at first glance, and I have never played with it before. > > I will need to output all of the covariance matrices to one CSV or text > file (there's probably some sort of "append = TRUE" argument involved). > > Does anyone know how to do this easily?
very quickly I would try something like: # will write to the screen lapply(x.list, write.csv) # you will probably want something more interesting: lapply(x.list, function(element_i) { # get level of 'gen' from list element # make a filename, see ?paste # write out a file for each write.table(element_i, file=filename, row.names=FALSE, ...) } ) -- Dylan Beaudette Soil Resource Laboratory http://casoilresource.lawr.ucdavis.edu/ University of California at Davis 530.754.7341 ______________________________________________ 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.