R：基於另一個列表重復列表的元素

Question

我搜索過這個但是徒勞無功。 問題是我有兩個列表，首先是要重復的元素，例如

my.list<-list(c('a','b','c','d'), c('g','h'))

第二個列表是每個元素重復的次數

repeat.list<-list(c(5,7,6,1), c(2,3))

我想創建一個新列表，其中my.list中的每個元素都基於repeat.list重復，即結果：

[[1]]
[1] "a" "a" "a" "a" "a" "b" "b"  "b" "b" "b" "b" "b" "c" "c" "c" "c" "c" "c" "d" 
[[2]]
[1] "g" "g" "h" "h" "h" 

預先感謝您的幫助

Answer 1

使用mapply ：

mapply(rep, my.list, repeat.list)
[[1]]
 [1] "a" "a" "a" "a" "a" "b" "b" "b" "b" "b" "b" "b" "c" "c" "c" "c" "c" "c" "d"

[[2]]
[1] "g" "g" "h" "h" "h"

---

lapply也有訣竅，但更冗長：

lapply(seq_along(my.list), function(i)rep(my.list[[i]], repeat.list[[i]]))
[[1]]
 [1] "a" "a" "a" "a" "a" "b" "b" "b" "b" "b" "b" "b" "c" "c" "c" "c" "c" "c" "d"

[[2]]
[1] "g" "g" "h" "h" "h"