Question

我有两个这样的矢量：

      a <- c(a,b,c)
      b <- c(1,2,3)

我想创建一个如下所示的矩阵：

      z <- matrix(c('a','a','a','b','b','b','c','c','c',1,2,3,1,2,3,1,2,3),nrow=9)
      z
         [,1] [,2]
    [1,] "a"  "1" 
    [2,] "a"  "2" 
    [3,] "a"  "3" 
    [4,] "b"  "1" 
    [5,] "b"  "2" 
    [6,] "b"  "3" 
    [7,] "c"  "1" 
    [8,] "c"  "2" 
    [9,] "c"  "3"

我如何在R？

中执行此操作

Answer 1

您可以使用expand.grid：

 a <- c("a","b","c")
 b <- c(1,2,3)
 expand.grid(a, b)  

  Var1 Var2
1    a    1
2    b    1
3    c    1
4    a    2
5    b    2
6    c    2
7    a    3
8    b    3
9    c    3

Answer 2

您也可以使用：

 library(data.table)
 as.matrix(CJ(a,b))
 #     V1  V2 
 #[1,] "a" "1"
 #[2,] "a" "2"
 #[3,] "a" "3"
 #[4,] "b" "1"
 #[5,] "b" "2"
 #[6,] "b" "3"
 #[7,] "c" "1"
 #[8,] "c" "2"
 #[9,] "c" "3"

R - 随机组合两个向量

2 个答案: