假设我们有一个如下列表：
[[1]]
[1] "preserver"
[[2]]
[1] "person, individual"
[[3]]
[1] "organism, being" "causal agent"
[[4]]
[1] "living thing" "physical entity"
[[5]]
[1] "unit" "entity"
[[6]]
[1] "object"
[[7]]
[1] "physical entity"
获得如下：
list("preserver", "person, individual", c("organism, being", "causal agent"), c("living thing", "physical entity"), c("unit", "entity"), "object", "physical entity")
假设此列表的每个元素代表一个树的级别，我正在寻找一种方法来创建这样一个树。
例如，在这种情况下，输出树将是：
[[1]]
[[1]]$o
[1] "preserver"
[[1]]$h
[[1]]$h[[1]]
[[1]]$h[[1]]$o
[1] "person, individual"
[[1]]$h[[1]]$h
[[1]]$h[[1]]$h[[1]]
[[1]]$h[[1]]$h[[1]]$o
[1] "organism, being"
[[1]]$h[[1]]$h[[1]]$h
[[1]]$h[[1]]$h[[1]]$h[[1]]
[[1]]$h[[1]]$h[[1]]$h[[1]]$o
[1] "living thing"
[[1]]$h[[1]]$h[[1]]$h[[1]]$h
[[1]]$h[[1]]$h[[1]]$h[[1]]$h[[1]]
[[1]]$h[[1]]$h[[1]]$h[[1]]$h[[1]]$o
[1] "unit"
[[1]]$h[[1]]$h[[1]]$h[[1]]$h[[1]]$h
[[1]]$h[[1]]$h[[1]]$h[[1]]$h[[1]]$h[[1]]
[[1]]$h[[1]]$h[[1]]$h[[1]]$h[[1]]$h[[1]]$o
[1] "object"
[[1]]$h[[1]]$h[[1]]$h[[1]]$h[[1]]$h[[1]]$h
[[1]]$h[[1]]$h[[1]]$h[[1]]$h[[1]]$h[[1]]$h[[1]]
[[1]]$h[[1]]$h[[1]]$h[[1]]$h[[1]]$h[[1]]$h[[1]]$o
[1] "physical entity"
[[1]]$h[[1]]$h[[2]]
[[1]]$h[[1]]$h[[2]]$o
[1] "causal agent"
[[1]]$h[[1]]$h[[2]]$h
[[1]]$h[[1]]$h[[2]]$h[[1]]
[[1]]$h[[1]]$h[[2]]$h[[1]]$o
[1] "physical entity"
[[1]]$h[[1]]$h[[2]]$h[[1]]$h
[[1]]$h[[1]]$h[[2]]$h[[1]]$h[[1]]
[[1]]$h[[1]]$h[[2]]$h[[1]]$h[[1]]$o
[1] "entity"
从此列表中手动创建：
list(structure(list(o = "preserver", h = list(structure(list(o = "person, individual", h = list(structure(list(o = "organism, being", h = list(structure(list(o = "living thing", h = list(structure(list(o = "unit", h = list(structure(list(o = "object", h = list(structure(list(o = "physical entity"), .Names = "o"))), .Names = c("o", "h")))), .Names = c("o", "h")))), .Names = c("o", "h")))), .Names = c("o", "h")), structure(list(o = "causal agent", h = list(structure(list(o = "physical entity", h = list(structure(list(o = "entity"), .Names = "o"))), .Names = c("o", "h")))), .Names = c("o", "h")))), .Names = c("o", "h")))), .Names = c("o", "h")))
关于解决方案：我在考虑Reduce，但我仍然无法找到解决方案。
另外，我想知道以其他方式表示这棵树的可能性（即不是通过这个巨大的嵌套列表;例如环境？）。
提前感谢您的帮助。