On Sun, 22 Aug 2010, david h shanabrook wrote:
I am working with a large sparse matrix trying replace all 1 values with 0.
The normal method doesn't work. Here is a small example:
x <- Matrix(0,nrow=10,ncol=10,sparse=TRUE)
x[,1] <- 1:2
x
10 x 10 sparse Matrix of class "dgCMatrix"
[1,] 1 . . . . . . . . .
[2,] 2 . . . . . . . . .
[3,] 1 . . . . . . . . .
[4,] 2 . . . . . . . . .
[5,] 1 . . . . . . . . .
[6,] 2 . . . . . . . . .
[7,] 1 . . . . . . . . .
[8,] 2 . . . . . . . . .
[9,] 1 . . . . . . . . .
[10,] 2 . . . . . . . . .
x[x==1] <- 0
Error in .local(x, i, j, ..., value) :
not-yet-implemented 'Matrix[<-' method
Suggestions? Any solution must be memory efficient as my sparse matrix is
large.
Looks like
attr( x, "x" )[ attr( x, "x" ) == 1 ] <- 0
should do it, but does not reduce the density of the matrix. In order to
get that you'll need to do
x <- drop0(x)
HTH,
Chuck
dhs
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Charles C. Berry (858) 534-2098
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