如何在 lapply 列表中使用条件 lapply、Filter、Between 在 R 中进行过滤？

Question

我有这个：

res.list<-list(c("X2", "X3", "X4"), c("X2", "X3", "X4"), c("X1", "X2", "X3"))

result<- lapply(res.list, function(x) {
      unlist(lapply(seq_along(x), function(y) combn(x, y, list)), recursive = FALSE)
    })
result<-lapply(result, Filter,f = function(x){
    ifelse(
    seq_along(result)==1, 
    between(length(x),1,3),
    between(length(x),2,2)
    ) %>%.[!is.na(.)]})

1- 我有一个列表“res.list”

2- 合并第 1 至“n”列而不重复。

3-按条件筛选结果，删除元素为NULL

预期输出：“结果”

[[1]]
[[1]][[1]][1] "X2"
[[1]][[2]][1] "X3"
[[1]][[3]][1] "X4"
[[1]][[4]][1] "X2" "X3"
[[1]][[5]][1] "X2" "X4"
[[1]][[6]][1] "X3" "X4"
[[1]][[7]][1] "X2" "X3" "X4"

[[2]]
[[2]][[4]][1] "X2" "X3"
[[2]][[5]][1] "X2" "X4"
[[2]][[6]][1] "X3" "X4"

[[3]]
[[3]][[4]][1] "X2" "X3"
[[3]][[5]][1] "X2" "X4"
[[3]][[6]][1] "X3" "X4"

代码未return结果预期输出，如果您有任何改进想法并使其更通用，那将很有启发性。

此致

Answer 1

我们可能需要

result[-1] <- lapply(result[-1], \(x) x[between(lengths(x), 1, 2)])

如何在 lapply 列表中使用条件 lapply、Filter、Between 在 R 中进行过滤？

How to filter in lapply list with conditionals lapply, Filter, Between in R?

r

lapply