nr <- 2
nc <- 4
rxc <- nr*nc
m1 <- Matrix(0, nrow = nr, ncol = rxc, sparse = TRUE)
col <- 0
for(r in 1:nr){
m1[r,((r-1)*nc+1) :(((r-1)*nc+1)+3)] <- 1
col <- col+1
}
Desired Output:
期望的输出:
[1,] 1 1 1 1 . . . .
[2,] . . . . 1 1 1 1
This works, but its very slow as I have to do it for 10 Million rows. Is there any better way do it in R ?
这是可行的,但它非常慢,因为我要用1000万行。有没有更好的方法用R表示?
1 个解决方案
#1
3
Use matrix indexing, which uses a two column matrix of row/column to determine which cells are changed:
使用矩阵索引,使用行/列的两列矩阵来确定哪些单元格被更改:
m1[cbind(rep(1:nr,each=nc),1:(nr*nc))] <- 1
m1
#2 x 8 sparse Matrix of class "dgCMatrix"
#
#[1,] 1 1 1 1 . . . .
#[2,] . . . . 1 1 1 1
#1
3
Use matrix indexing, which uses a two column matrix of row/column to determine which cells are changed:
使用矩阵索引,使用行/列的两列矩阵来确定哪些单元格被更改:
m1[cbind(rep(1:nr,each=nc),1:(nr*nc))] <- 1
m1
#2 x 8 sparse Matrix of class "dgCMatrix"
#
#[1,] 1 1 1 1 . . . .
#[2,] . . . . 1 1 1 1