R:从 "triangular"形式的向量创建列表

Question

我发现很难提出问题，但我想找到一种聪明的方法(不使用循环)来获得以下结果:

> my.vector = letters[1:6]
> print(my.vector)
[1] "a" "b" "c" "d" "e" "f"
> 
> my.list = (rep(list(NA),6))
> for (i in 1:length(my.vector)){
+   x = my.vector[1:i]
+   my.list[[i]] = x
+ }
> print(my.list)
[[1]]
[1] "a"

[[2]]
[1] "a" "b"

[[3]]
[1] "a" "b" "c"

[[4]]
[1] "a" "b" "c" "d"

[[5]]
[1] "a" "b" "c" "d" "e"

[[6]]
[1] "a" "b" "c" "d" "e" "f"

提前致谢

加布里埃尔。

Answer 1

你可以这样做:

lapply(seq_along(my.vector), head, x = my.vector)