如何在lapply列表中过滤条件lapply, filter, Between在R中?

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-将列1与"n"没有重复。

3-按条件过滤结果，删除元素为NULL

期望输出:"result">

[[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"

代码没有返回结果预期输出，如果你有任何改进的想法，让它更通用，这将是有启发的。

问好

Answer 1

我们可能需要

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