R中多个向量的组合 [英] Combinations of multiple vectors in R

问题描述

我不确定置换是否是正确的词。我想给定一组n个向量（即 [1,2] ， [3,4] 和 [2,3] ）将它们全部置换并得到

I'm not sure if permutations is the correct word for this. I want to given a set of n vectors (i.e. [1,2],[3,4] and [2,3]) permute them all and get an output of

[1,3,2],[1,3,3],[1,4,2],[1,4,3],[2,3,2] etc.

R中是否有可以执行此操作的操作？

Is there an operation in R that will do this?

推荐答案

这是将向量存储在列表中并使用 do.call（）为您安排适当的函数调用的有用情况。 expand.grid（）是您想要的标准函数。但是，您不必键入或命名单个向量，请尝试：

This is a useful case for storing the vectors in a list and using do.call() to arrange for an appropriate function call for you. expand.grid() is the standard function you want. But so you don't have to type out or name individual vectors, try:

> l <- list(a = 1:2, b = 3:4, c = 2:3)
> do.call(expand.grid, l)
  a b c
1 1 3 2
2 2 3 2
3 1 4 2
4 2 4 2
5 1 3 3
6 2 3 3
7 1 4 3
8 2 4 3

但是，出于我的聪明，事实证明 expand.grid（）接受列表：

However, for all my cleverness, it turns out that expand.grid() accepts a list:

> expand.grid(l)
  a b c
1 1 3 2
2 2 3 2
3 1 4 2
4 2 4 2
5 1 3 3
6 2 3 3
7 1 4 3
8 2 4 3

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