> y<-matrix(1:20,nrow = 5,ncol = 4)
> y
[,1] [,2] [,3] [,4]
[1,] 1 6 11 16
[2,] 2 7 12 17
[3,] 3 8 13 18
[4,] 4 9 14 19
[5,] 5 10 15 20
> cells <- c(1,26,24,68)
> rnames <- c("R1","R2")
> cnames <- c("C1","C2")
> #按行填充
> mymatrix <- matrix(cells,nrow = 2,ncol = 2,byrow = TRUE,dimnames = list(rnames,cnames))
> mymatrix
C1 C2
R1 1 26
R2 24 68
> #按列填充
> mymatrix <- matrix(cells,nrow = 2,ncol = 2,byrow = FALSE,dimnames = list(rnames,cnames))
> mymatrix
C1 C2
R1 1 24
R2 26 68
> #矩阵下标使用
>
> i <- matrix(1:10,nrow = 2)
> i
[,1] [,2] [,3] [,4] [,5]
[1,] 1 3 5 7 9
[2,] 2 4 6 8 10
> i[2,]
[1] 2 4 6 8 10
> i[,2]
[1] 3 4
> i[1,4]
[1] 7
> i[1,c(4,5)]
[1] 7 9
