> 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?



      
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