Hi,
I think you could also use this way (via array, see
http://r.789695.n4.nabble.com/apply-over-list-of-data-frames-td3057968.html)
b <- list()
b[[1]] = matrix(1:4, 2, 2)
b[[2]] = matrix(10:13, 2, 2)
b[[3]] = matrix(20:23, 2, 2)
b.a <- array(unlist(b), dim=c(2, 2, 3))
(b.mean <- apply(X = b.a, MARGIN = c(1, 2), FUN = mean))
(b.sum <- apply(X = b.a, MARGIN = c(1, 2), FUN = sum))
HTH
Patrick
Am 24.03.2011 16:07, schrieb Hui Du:
Hi All,
Suppose I have data like
b[[1]] = matrix(1:4, 2, 2)
b[[2]] = matrix(10:13, 2, 2)
b[[3]] = matrix(20:23, 2, 2)
[[1]]
[,1] [,2]
[1,] 1 3
[2,] 2 4
[[2]]
[,1] [,2]
[1,] 10 12
[2,] 11 13
[[3]]
[,1] [,2]
[1,] 20 22
[2,] 21 23
Now I want to calculate the mean of each cell across the list.
For example mean of (b[[1]][1,1], b[[2]][1,1], b[[3]][1,1]), mean of
(b[[1]][1,2], b[[2]][1,2], b[[3]][1,2]) etc. e.g. mean of (1, 10, 20), mean
of(3, 12, 22). Could somebody tell me how to do it? Thank you in advance.
HXD
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