从列表中删除重复的元素

我有一个list of character vectors:

my.list <- list(e1 = c("a","b","c","k"),e2 = c("b","d","e"),e3 = c("t","d","g","a","f"))

我正在寻找一个function对于任何character出现不止一次list's vectors（在每个vector a character只能出现一次），只会保留第一次出现。

因此，此示例的结果列表将是：

res.list <- list(e1 = c("a","b","c","k"),e2 = c("d","e"),e3 = c("t","g","f"))

请注意，有可能整个vector in the list被消除，以便结果中的元素数量list不一定必须等于输入list.

We can unlist the list，得到一个逻辑list using duplicated并根据逻辑索引提取 'my.list' 中的元素

un <- unlist(my.list)
res <- Map(`[`, my.list, relist(!duplicated(un), skeleton = my.list))
identical(res, res.list)
#[1] TRUE