矩阵列表中每个元素的均值 [英] Mean of each element of a list of matrices

问题描述

我有一个包含三个矩阵的列表:

I have a list with three matrixes:

a<-matrix(runif(100))
b<-matrix(runif(100))
c<-matrix(runif(100))

mylist<-list(a,b,c)

我想获得三个矩阵中每个元素的均值.

I would like to obtain the mean of each element in the three matrices.

我试过:aaply(laply(mylist, as.matrix), c(1, 1), mean) 但这会返回每个矩阵的均值，而不是将每个元素的均值作为rowMeans() 会.

I tried: aaply(laply(mylist, as.matrix), c(1, 1), mean) but this returns the means of each matrix instead of taking the mean of each element as rowMeans() would.

推荐答案

也许你想要的是:

> set.seed(1)
> a<-matrix(runif(4)) 
> b<-matrix(runif(4))
> c<-matrix(runif(4))
> mylist<-list(a,b,c)  # a list of 3 matrices 
> 
> apply(simplify2array(mylist), c(1,2), mean)
          [,1]
[1,] 0.3654349
[2,] 0.4441000
[3,] 0.5745011
[4,] 0.5818541

apply 调用中 MARGIN 的向量 c(1,2) 表示函数 mean 应该应用于行和列(同时)，请参阅 ?apply 了解更多详情.

The vector c(1,2) for MARGIN in the apply call indicates that the function mean should be applied to rows and columns (both at once), see ?apply for further details.

另一种选择是使用 Reduce 函数

Another alternative is using Reduce function

> Reduce("+", mylist)/ length(mylist)
          [,1]
[1,] 0.3654349
[2,] 0.4441000
[3,] 0.5745011
[4,] 0.5818541

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