[R] Calculate Mean of Column Vectors?

Spencer Graves spencer.graves at pdf.com
Tue Jan 11 05:14:18 CET 2005


      Have you considered the following: 

    apply(y, 1, mean)

      Alternatively: 
          
y.means <- rep(NA, 3)
for(i in 1:3)
  y.means[i] <- mean(y[i,])

      hope this helps.  spencer graves

Thomas Hopper wrote:

> Hello,
>
> I've got an array defined as y <- rnorm(3000), dim(y) <- c(3, 1000).
>
> I'd like to produce a 1000-element vector z that is the mean of the 
> corresponding elements of y (like z[1,1] <- mean(y[1,1], y[2,1], 
> y[3,1])), but being new to R, I'm not sure how to do this for all 
> elements at once (or, at least, simply). Any help is appreciated.
>
> Thanks,
>
> Tom
>
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