R users,
This probably involves a simple incantation of one of the flavors of apply... that I can't yet figure out. Consider a list of data frames. I'd like to apply a function (mean) across the list and return a dataframe of the same dimensions where each cell represents the mean of that cell across all dataframes. 
 
# set up the list
x <- vector("list",2)
names(x) <- c("one","two")
# add data to the list 
for(i in 1:2){
 y = i^2
 x[[i]] <- data.frame("a"=c(y,2*y,3*y),"b"=c(y+1,y+2,y+3),"c"=c(2*y+1,2*y+2,2*y+3))
 }
#show the list
> x
$one
  a b c
1 1 2 3
2 2 3 4
3 3 4 5
 
$two
   a b  c
1  4 5  9
2  8 6 10
3 12 7 11
#the result should be
 a b c
1 2.5 3.5 6
2 5 4.5 7
3 7.5 5.5 8
 
Can anyone direct me down the right path?
 
Thanks in advance
Tim Howard
 
 
 

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