如何在R中获取字符向量的所有可能子集? [英] How to get all possible subsets of a character vector in R?

问题描述

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:

I am trying to get a list or data frame containing the following entries:

"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！

The goal would be to get all possible subsets while the order doesn't matter, that is "text1" "text2" NA is equivalent to "text2" "text1" NA. I very much appreciate any help!

推荐答案

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"

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