aperm方法
Transpose an array by permuting its dimensions and optionally resizing it.
aperm(a, perm, ...)
a
the array to be transposed.
perm
the subscript（下标） permutation vector, usually a permutation（组合） of the integers 1:n, where n is the number of dimensions of a. When a has named dimnames, it can be a character vector of length n giving a permutation of those names. The default (used whenever perm has zero length) is to reverse the order of the dimensions.
permutation
置换；排列（方式）；组合（方式）
交换；变换；彻底改变
> x <- array(1:24, 2:4)> x, , 1[,1] [,2] [,3][1,] 1 3 5[2,] 2 4 6, , 2[,1] [,2] [,3][1,] 7 9 11[2,] 8 10 12, , 3[,1] [,2] [,3][1,] 13 15 17[2,] 14 16 18, , 4[,1] [,2] [,3][1,] 19 21 23[2,] 20 22 24> xt <- aperm(x, c(2,1,3))> xt, , 1[,1] [,2][1,] 1 2[2,] 3 4[3,] 5 6, , 2[,1] [,2][1,] 7 8[2,] 9 10[3,] 11 12, , 3[,1] [,2][1,] 13 14[2,] 15 16[3,] 17 18, , 4[,1] [,2][1,] 19 20[2,] 21 22[3,] 23 24
让我来解释下perm的意思吧
原来的数组的维度是行，列，层分别为2,3,4
现在perm=2,1,3
2的意思是原来下标是2的那个数（排在第二个的参数），现在排在第一位（行）
1的意思是原来下标是1的那个数，现在排在第2位（列）
3的意思是原来下标是3的那个数，现在排在第三位（层）
所以perm=2,1,3的等价于(3,2,4)