r - 如何在R中获取字符向量的所有可能子集？

Question

具有以下向量:

c("test1","test2","test3")

我正在尝试获取包含以下条目的列表或数据框:

"test1" "test2" "test3"
"test1" "test2" NA
"test1" NA "test3"
"test1"  NA NA
NA  "test2" "test3"
NA  "test2" NA
NA  NA "test3"

目标是获取所有可能的子集，而顺序无关紧要，即“text1”“text2”NA 等效于“text2”“text1”NA。我非常感谢任何帮助!

Answer 1

您可以使用 combn :

res <- unlist(lapply(1:3, combn, 
                     x = c("test1","test2","test3"), simplify = FALSE), 
              recursive = FALSE)
res <- sapply(res, `length<-`, 3)
#        [,1]    [,2]    [,3]    [,4]    [,5]    [,6]    [,7]   
#[1,] "test1" "test2" "test3" "test1" "test1" "test2" "test1"
#[2,] NA      NA      NA      "test2" "test3" "test3" "test2"
#[3,] NA      NA      NA      NA      NA      NA      "test3"