所有长度的无序组合

本文介绍了所有长度的无序组合的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我正在寻找一个函数，该函数可以将向量的所有无序组合返回给我.例如

I am looking a function that return me all the unordered combination of a vector. eg

x <- c('red','blue','black') uncomb(x) [1]'red' [2]'blue' [3]'black' [4]'red','blue' [5]'blue','black' [6]'red','black' [7]'red','blue','black'

我猜想某些库中有一个函数可以执行此操作，但是找不到.我正在尝试使用gtool的permutations，但这不是我想要的功能.

I guess that there is a function in some library that do this, but in can't find it. I am trying with permutations of gtool but it is not the function i am looking for.

推荐答案

您可以在combn()函数的m参数上应用长度为x的序列.

You could apply a sequence the length of x over the m argument of the combn() function.

x <- c("red", "blue", "black") do.call(c, lapply(seq_along(x), combn, x = x, simplify = FALSE)) # [[1]] # [1] "red" # # [[2]] # [1] "blue" # # [[3]] # [1] "black" # # [[4]] # [1] "red" "blue" # # [[5]] # [1] "red" "black" # # [[6]] # [1] "blue" "black" # # [[7]] # [1] "red" "blue" "black"

如果您喜欢矩阵结果，则可以将stringi::stri_list2matrix()应用于上面的列表.

If you prefer a matrix result, then you can apply stringi::stri_list2matrix() to the list above.

stringi::stri_list2matrix( do.call(c, lapply(seq_along(x), combn, x = x, simplify = FALSE)), byrow = TRUE ) # [,1] [,2] [,3] # [1,] "red" NA NA # [2,] "blue" NA NA # [3,] "black" NA NA # [4,] "red" "blue" NA # [5,] "red" "black" NA # [6,] "blue" "black" NA # [7,] "red" "blue" "black"