如何获得R中字符向量的所有可能子集？

Question

有以下向量:

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

我想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"

目标是获得所有可能的子集,而顺序无关紧要,即"text1""text2"NA等同于"text2""text1"NA.我非常感谢任何帮助!

Answer 1

你可以使用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"

Answer 2

有一套具有相关功能的套装.

library(sets)
a <- c("test1","test2","test3")
set_power(a)

{{},{"test1"},{"test2"},{"test3"},{"test1","test2"},{"test1","test3"},{"test2","test3" },{"test1","test2","test3"}}

这将返回所有子集的集合.

Answer 3

使用combn和data.table :: rbindlist和fill = TRUE选项来创建NA值.

#data
a <- c("test1","test2","test3")

#result
data.table::rbindlist(
        sapply(1:3, function(i) as.data.frame(t(combn(a, i)))), fill = TRUE)

#output
#       V1    V2    V3
# 1: test1    NA    NA
# 2: test2    NA    NA
# 3: test3    NA    NA
# 4: test1 test2    NA
# 5: test1 test3    NA
# 6: test2 test3    NA
# 7: test1 test2 test3