Hi all,
I am wondering if this is a bug in the Matrix package or if it something
that I am just getting wrong...here is an example:
> m = matrix(0,4,4)
> dimnames(m) = list(letters[1:4], letters[5:8])
> r = c("a","b","a","d")
> m[r,2] = 1
> m
e f g h
a 0 1 0 0
b 0 1 0 0
c 0 0 0 0
d 0 1 0 0
> M = Matrix(0,4,4)
> dimnames(M) = list(letters[1:4], letters[5:8])
> M[r,2] = 1
> M
4 x 4 sparse Matrix of class "dgCMatrix"
a . 2 . .
b . 1 . .
c . . . .
d . 1 . .
The documentation reads:
" Most of the time, the function works via a traditional (_full_)
'matrix'. However, 'Matrix(0, nrow,ncol)' directly constructs an
"empty" sparseMatrix, as does 'Matrix(FALSE, *)'."
So is this when an exception comes, and if so can someone explain to me why
we get the 2? It would seem that it should just reassign the 1 to a 1 not
add the number of times it is assigning a 1.
Cheers,
--Tony
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