[R] Annoyance in as.numeric

[Taylor, Z Todd]

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: r-help-bounces at r-project.org 
> [mailto:r-help-bounces at r-project.org] On Behalf Of Gavin Simpson
> Sent: Monday, June 16, 2008 2:31 PM
> To: markleeds at verizon.net
> Cc: r-help at r-project.org
> Subject: Re: [R] Annoyance in as.numeric
> 
> On Mon, 2008-06-16 at 15:35 -0500, markleeds at verizon.net 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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> ______________________________________________
> R-help at r-project.org mailing list
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> PLEASE do read the posting guide 
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>