在嵌套列表中应用函数 [英] Applying a function across nested list

问题描述

说，我有以下列表

raw <- list(list(1:2, 2:3, 3:4), list(4:5, 5:6, 6:7), list(7:8, 8:9, 9:10))

我想找到最外层列表中相应条目的均值.预期的输出将类似于

I would like to find the mean of the corresponding entries of the out-most list. The expected output would be something like

[[1]]
[1] 4 5

[[2]]
[1] 5 6

[[3]]
[1] 6 7

这是因为1:2，4:5和7:8的平均值将是4:5.

This is because the mean of 1:2, 4:5, and 7:8 would be 4:5.

我一直在尝试lapply(raw, function(x) lapply(x, mean))之类的东西，但是显然它没有返回期望的输出.

I have been experimenting with stuff like lapply(raw, function(x) lapply(x, mean)), but apparently it doesn't return the desired output.

推荐答案

1

n = length(raw[[1]])
lapply(1:n, function(i){
    d = do.call(rbind, lapply(seq_along(raw), function(j){
        raw[[j]][[i]]
    }))
    apply(d, 2, mean)
})
#[[1]]
#[1] 4 5

#[[2]]
#[1] 5 6

#[[3]]
#[1] 6 7

2

aggregate(. ~ ind, do.call(rbind, lapply(raw, function(x)
    data.frame(cbind(do.call(rbind, x), ind = seq_along(x))))), mean)
#  ind V1 V2
#1   1  4  5
#2   2  5  6
#3   3  6  7

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