如何在R中的字符串向量中创建元素的无序组合列表？
元素的无序组合意味着值的组合没有任何特定的安排。例如，如果我们具有三个值1、2和3，那么它们可以按以下无序排列方式进行排列-
"one" "two" "three" "one" "two" "one" three" "two" "three" "one" "two" "three"
示例
x<-c("India","China","Russia","Canada") unlist(lapply(seq_along(x),combn,x=x,simplify=FALSE),recursive=FALSE)输出结果
[[1]] [1] "India" [[2]] [1] "China" [[3]] [1] "Russia" [[4]] [1] "Canada" [[5]] [1] "India" "China" [[6]] [1] "India" "Russia" [[7]] [1] "India" "Canada" [[8]] [1] "China" "Russia" [[9]] [1] "China" "Canada" [[10]] [1] "Russia" "Canada" [[11]] [1] "India" "China" "Russia" [[12]] [1] "India" "China" "Canada" [[13]] [1] "India" "Russia" "Canada" [[14]] [1] "China" "Russia" "Canada" [[15]] [1] "India" "China" "Russia" "Canada"
示例
y<-c("Winter","Rainy","Summer") unlist(lapply(seq_along(y),combn,x=y,simplify=FALSE),recursive=FALSE)输出结果
[[1]] [1] "Winter" [[2]] [1] "Rainy" [[3]] [1] "Summer" [[4]] [1] "Winter" "Rainy" [[5]] [1] "Winter" "Summer" [[6]] [1] "Rainy" "Summer" [[7]] [1] "Winter" "Rainy" "Summer"