I have the following [10 x 10] sparse matrix:
library(Matrix)
m = as(diag(10), 'sparseMatrix')
m
10 x 10 sparse Matrix of class "dgCMatrix"
[1,] 1 . . . . . . . . .
[2,] . 1 . . . . . . . .
[3,] . . 1 . . . . . . .
[4,] . . . 1 . . . . . .
[5,] . . . . 1 . . . . .
[6,] . . . . . 1 . . . .
[7,] . . . . . . 1 . . .
[8,] . . . . . . . 1 . .
[9,] . . . . . . . . 1 .
[10,] . . . . . . . . . 1
If I do simple arithmetic on this, it now stores all of the zeros.
M = m + 1 - 1
M
10 x 10 Matrix of class "dgeMatrix"
[,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
[1,] 1 0 0 0 0 0 0 0 0 0
[2,] 0 1 0 0 0 0 0 0 0 0
[3,] 0 0 1 0 0 0 0 0 0 0
[4,] 0 0 0 1 0 0 0 0 0 0
[5,] 0 0 0 0 1 0 0 0 0 0
[6,] 0 0 0 0 0 1 0 0 0 0
[7,] 0 0 0 0 0 0 1 0 0 0
[8,] 0 0 0 0 0 0 0 1 0 0
[9,] 0 0 0 0 0 0 0 0 1 0
[10,] 0 0 0 0 0 0 0 0 0 1
I know that I can make this new matrix sparse, but is there any way to make R do this automatically?
M = as(M, 'sparseMatrix')
It calculates m+1-1 as (m+1)-1 and m+1 is not sparse so from that point on you don't have a sparse matrix.
Try m+(1-1).