用相同的索引值对列表的所有元素进行子设置 [英] subsetting all elements of a list by the same index values

问题描述

可能微不足道，但是我没有找到解决方案.我正在尝试通过相同的索引值对列表的所有元素进行子集化.

Probably trivial, but I didn't find a solution. I am trying to subset all elements of a list by the same index values.

假设我的清单是: mylist = list(seq(22,30,2)，c(1:5)，rep(8,5))

这给了我

[[1]]
[1] 22 24 26 28 30

[[2]]
[1] 1 2 3 4 5

[[3]]
[1] 8 8 8 8 8

我试图只提取值 [2:4] 并删除元素的其他值，所以我得到一个看起来像

I am trying to extract only the values [2:4] and drop the other values of the element, so i get a list that looks like

[[1]]
[1]  24 26 28 

[[2]]
[1] 2 3 4 

[[3]]
[1] 8 8 8 

我尝试过foreach的组合

I have tried a combination of foreach an lapply

sub = foreach(i = c(1:3))％do％{lapply(mylist，function(x){mylist [[i]] [c(2:4)]})}

但是我最终得到了三倍复制

However I end up with a threefold replication

[[1]]
[[1]][[1]]
[1] 24 26 28

[[1]][[2]]
[1] 24 26 28

[[1]][[3]]
[1] 24 26 28


[[2]]
[[2]][[1]]
[1] 2 3 4

[[2]][[2]]
 [1] 2 3 4

[[2]][[3]]
[1] 2 3 4


[[3]]
[[3]][[1]]
[1] 8 8 8

[[3]][[2]]
[1] 8 8 8

[[3]][[3]]
[1] 8 8 8

我要去哪里错了?

推荐答案

存入@Richard Scriven

credit to @Richard Scriven

解决方案:

lapply(mylist, "[", 2:4)

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