如何从多个列向量创建矩阵？
我知道我可以轻松地创建一个带有列向量的数据框:
> colA <- 1:5
> colB <- 21:25
> colC <- 31:35
> data.frame(colA, colB, colC)
colA colB colC
1 1 21 31
2 2 22 32
3 3 23 33
4 4 24 34
5 5 25 35
但是,当我尝试时matrix(),它会给我意想不到的结果,如下所示.如何创建我想要的矩阵？我知道我能做到as.matrix(df),这很好地保留了列名,但我正在寻找一种更直接的方法.
> matrix(colA, colB, colC)
[,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10] [,11] [,12] [,13]
[1,] 1 2 3 4 5 1 2 3 4 5 1 2 3
[2,] 2 3 4 5 1 2 3 4 5 1 2 3 4
[3,] 3 4 5 1 2 3 4 5 1 2 3 4 5
[4,] 4 5 1 2 3 4 5 1 2 3 4 5 1
[5,] 5 1 2 3 4 5 1 2 3 4 5 1 2
[6,] 1 2 3 4 5 1 2 3 4 5 1 2 3
[7,] 2 3 4 5 1 2 3 4 5 1 2 3 4
[8,] 3 4 5 1 2 3 4 5 1 2 3 4 5
[9,] 4 5 1 2 3 4 5 1 2 3 4 5 1
[10,] 5 1 2 3 4 5 1 2 3 4 5 1 2
[11,] 1 2 3 4 5 1 2 3 4 5 1 2 3
[12,] 2 3 4 5 1 2 3 4 5 1 2 3 4
[13,] 3 4 5 1 2 3 4 5 1 2 3 4 5
[14,] 4 5 1 2 3 4 5 1 2 3 4 5 1
[15,] 5 1 2 3 4 5 1 2 3 4 5 1 2
[16,] 1 2 3 4 5 1 2 3 4 5 1 2 3
[17,] 2 3 4 5 1 2 3 4 5 1 2 3 4
[18,] 3 4 5 1 2 3 4 5 1 2 3 4 5
[19,] 4 5 1 2 3 4 5 1 2 3 4 5 1
[20,] 5 1 2 3 4 5 1 2 3 4 5 1 2
[21,] 1 2 3 4 5 1 2 3 4 5 1 2 3
[,14] [,15] [,16] [,17] [,18] [,19] [,20] [,21] [,22] [,23] [,24] [,25]
[1,] 4 5 1 2 3 4 5 1 2 3 4 5
[2,] 5 1 2 3 4 5 1 2 3 4 5 1
[3,] 1 2 3 4 5 1 2 3 4 5 1 2
[4,] 2 3 4 5 1 2 3 4 5 1 2 3
[5,] 3 4 5 1 2 3 4 5 1 2 3 4
[6,] 4 5 1 2 3 4 5 1 2 3 4 5
[7,] 5 1 2 3 4 5 1 2 3 4 5 1
[8,] 1 2 3 4 5 1 2 3 4 5 1 2
[9,] 2 3 4 5 1 2 3 4 5 1 2 3
[10,] 3 4 5 1 2 3 4 5 1 2 3 4
[11,] 4 5 1 2 3 4 5 1 2 3 4 5
[12,] 5 1 2 3 4 5 1 2 3 4 5 1
[13,] 1 2 3 4 5 1 2 3 4 5 1 2
[14,] 2 3 4 5 1 2 3 4 5 1 2 3
[15,] 3 4 5 1 2 3 4 5 1 2 3 4
[16,] 4 5 1 2 3 4 5 1 2 3 4 5
[17,] 5 1 2 3 4 5 1 2 3 4 5 1
[18,] 1 2 3 4 5 1 2 3 4 5 1 2
[19,] 2 3 4 5 1 2 3 4 5 1 2 3
[20,] 3 4 5 1 2 3 4 5 1 2 3 4
[21,] 4 5 1 2 3 4 5 1 2 3 4 5
[,26] [,27] [,28] [,29] [,30] [,31]
[1,] 1 2 3 4 5 1
[2,] 2 3 4 5 1 2
[3,] 3 4 5 1 2 3
[4,] 4 5 1 2 3 4
[5,] 5 1 2 3 4 5
[6,] 1 2 3 4 5 1
[7,] 2 3 4 5 1 2
[8,] 3 4 5 1 2 3
[9,] 4 5 1 2 3 4
[10,] 5 1 2 3 4 5
[11,] 1 2 3 4 5 1
[12,] 2 3 4 5 1 2
[13,] 3 4 5 1 2 3
[14,] 4 5 1 2 3 4
[15,] 5 1 2 3 4 5
[16,] 1 2 3 4 5 1
[17,] 2 3 4 5 1 2
[18,] 3 4 5 1 2 3
[19,] 4 5 1 2 3 4
[20,] 5 1 2 3 4 5
[21,] 1 2 3 4 5 1
Warning message:
In matrix(colA, colB, colC) :
data length [5] is not a sub-multiple or multiple of the number of rows [21]
您可以cbind用来生成所需的矩阵:
mat <- cbind(colA, colB, colC)
mat
# colA colB colC
# [1,] 1 21 31
# [2,] 2 22 32
# [3,] 3 23 33
# [4,] 4 24 34
# [5,] 5 25 35
class(mat)
# [1] "matrix"
你不明白你用的呼唤期待矩阵matrix(colA, colB, colC),因为你的论点越来越解释为第一,第二和第三个参数的matrix函数(又名data,nrow和ncol).如果您想使用矩阵函数,则需要将您的数据作为单个参数提供,例如mat <- matrix(c(colA, colB, colC), ncol=3).如果您使用此语法,则不会像我们一样从变量中获取列名cbind.