Hi Greg,
Here are two ways of doing it:
> mylist <- list(x = rpois(10, 10), y = rpois(10, 20), z = rpois(10, 5))
> mylist
$x
[1] 3 13 14 16 10 7 3 5 12 14
$y
[1] 17 16 26 13 23 24 16 28 23 12
$z
[1] 2 6 5 5 5 1 9 11 6 4
>
> colMeans(do.call(rbind, mylist), na.rm = TRUE)
[1] 7.333333 11.666667 15.000000 11.333333 12.666667 10.666667 9.333333
14.666667 13.666667
[10] 10.000000
>
> Reduce("+", mylist)/length(mylist)
[1] 7.333333 11.666667 15.000000 11.333333 12.666667 10.666667 9.333333
14.666667 13.666667
[10] 10.000000
HTH,
Jorge
On Fri, Oct 29, 2010 at 6:46 PM, Gregory Ryslik <> wrote:
> Hi Everyone,
>
> I have a list of vectors like this (in this case it's 3 vectors but assume
> the vector count and the length of each vector is not known):
>
> [[1]]
> [1] 9 5 7 2 14 4 4 3
>
> [[2]]
> [1] 3 6 25 2 14 3 3 4
>
> [[3]]
> [1] 28 4 14 3 14 2 4 5
>
> What I want to do is take the average vertically. Thus I want to do 9+3+28
> /3, 5+6+4 /3, etc... and then have it return a vector. I'm assuming that if
> I can sum it, I can count it to so summing this would be just as helpful.
>
> I understand I can first go through each element of the list, get a vector,
> cbind into matrix and sum across but I was hoping to avoid that... I tried
> getting it to work with mapply but am having difficulties...
>
> Thanks!
>
> Kind regards,
> Greg
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