r - Element-wise mean over list of matrices -


this question has answer here:

suppose have list of matrices. convenient way calculate mean matrix on element element basic? suppose have list of matrices:

> <- matrix(c(1:9), 3, 3)  >      [,1] [,2] [,3] [1,]    1    4    7 [2,]    2    5    8 [3,]    3    6    9 > b <- matrix(c(2:10), 3, 3)  > b      [,1] [,2] [,3] [1,]    2    5    8 [2,]    3    6    9 [3,]    4    7   10 > my.list <- list(a, b)

so desired output should be:

     [,1] [,2] [,3] [1,]  1.5  4.5  7.5 [2,]  2.5  5.5  8.5 [3,]  3.5  6.5  9.5

you can use:

reduce("+", my.list) / length(my.list)

according comments, want both mean , sd implemented on list of matrices, , above ways not work smoothly sd. try instead :

apply(simplify2array(my.list), 1:2, mean) apply(simplify2array(my.list), 1:2, sd)

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