[R] applying cor.test to a (m, n) matrix

Yasir Kaheil kaheil at gmail.com
Fri May 9 08:23:37 CEST 2008


interesting request..I'm looking forward to the replies 
All I could come up with is putting it in two lines.. 
pr<-array(0,c(dim(x)[2],dim(x)[2])); 
for (i in 1:dim(x)[2]) for (j in 1:dim(x)[2])
pr[i,j]<-cor.test(x[,i],x[,j])$p.val;

y


Monica Pisica wrote:
> 
> 
> Hi everybody,
> 
> I would like to apply cor.test to a matrix with m rows and n columns and
> get the results in a list of matrices , one matrix for p.val, one for the
> statistic, one for the correlation and 2 for upper and lower confidence
> intervals, something analog with cor() applied to a matrix.
> 
> I have done my own function to get a matrix of p.values and i suppose i
> can build similar functions for all the others. But i have used for loops
> and i wonder if there is any way to actually use one of the functions from
> the "apply" family to do this in a quicker way.
> 
> Here is my little function:
> 
> cor.pval <- function(x, method = c("pearson", "kendal", "spearman"),
> digit=8) {
> n <- dim(x)[2]
> pval <- matrix(paste(rep("c", n*n), seq(1,n*n), sep = ""), n, n, byrow =
> T)
> for (i in 1:n) {
> 	for (j in 1:n){
> pval[i, j] <- cor.test(x[,i], x[,j], method = method)$p.value
>                                   }
>                    }
> pval <- matrix(round(as.numeric(pval),digit), n, n, byrow = T)
> rownames(pval) <- colnames(x)
> colnames(pval) <- colnames(x)
> return(pval)
> }
> 
> Thanks for any input,
> 
> Monica
> 
> 
> 
> 
> 
> 
> 
> _________________________________________________________________
> 
> 
> esh_messenger_052008
> ______________________________________________
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> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
> 
> 


-----
Yasir H. Kaheil
Catchment Research Facility
The University of Western Ontario 

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