I generally do something like
storage.mode(my.matrix) <- "double"
--Todd
--
Why do you recite at a play and play at a recital?
> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] On Behalf Of Gavin Simpson
> Sent: Monday, June 16, 2008 2:31 PM
> To: [EMAIL PROTECTED]
> Cc: r-help@r-project.org
> Subject: Re: [R] Annoyance in as.numeric
>
> On Mon, 2008-06-16 at 15:35 -0500, [EMAIL PROTECTED] wrote:
> > hi: you can do below but i don't know if it's worth it ?
> >
> > newx <- data.matrix(data.frame(x))
> > print(newx)
>
> That doesn't work Mark:
>
> > str(data.frame(x))
> 'data.frame': 2 obs. of 2 variables:
> $ X1: Factor w/ 2 levels "1","2": 1 2
> $ X2: Factor w/ 2 levels "3","4": 1 2
> > data.matrix(data.frame(x))
> X1 X2
> [1,] 1 1
> [2,] 2 2
>
> Which is as per documentation - the data.frame() coerces to
> factors and
> data.matrix represents factor by their internal values.
>
> One "solution" might be to save the dims and then reapply:
>
> > mat
> [,1] [,2]
> [1,] "1" "3"
> [2,] "2" "4"
> > dims <- dim(mat)
> > mat2 <- as.numeric(mat)
> > dim(mat) <- dims
> > mat2
> [,1] [,2]
> [1,] 1 3
> [2,] 2 4
>
> You could wrap this in a function:
>
> asMatrix <- function(x, ...) {
> dims <- dim(x)
> x <- as.double(x)
> dim(x) <- dims
> return(x)
> }
>
> It would be logical to define a method for as.double for
> matrix objects.
> However objects of class "matrix" are not objects in the sense of
> isObject() and hence method dispatch will not work in this case.
>
> HTH
>
> G
>
>
> >
> >
> > On Mon, Jun 16, 2008 at 4:22 PM, Alberto Monteiro wrote:
> >
> > > Why does as.numeric convert matrices and arrays to vectors?
> > >
> > > as.numeric(matrix(c("1", "2", "3", "4"), 2, 2))
> > > [1] 1 2 3 4
> > >
> > > I could only figure out ugly ways to bypass this, like:
> > >
> > > x <- matrix(c("1", "2", "3", "4"), 2, 2)
> > > array(as.numeric(x), dim = dim(x), dimnames = dimnames(x))
> > >
> > > Alberto Monteiro
> > >
> > > ______________________________________________
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> >
> > ______________________________________________
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