[R] convert a data.frame to matrix

[David Winsemius]

On May 16, 2013, at 1:46 PM, Hermann Norpois wrote:

> Hello,
> 
> I fail to tranfer data from a dataframe to a matrix.
> 
> jam is from a dataframe (and belongs still to the class dataframe) and
> should look like m (see below).
> 
>> jam
>  vec1 vec3  d1  d2
> 1  172  173 223 356
>> dput (jam)
> structure(list(vec1 = 172L, vec3 = 173L, d1 = 223L, d2 = 356L), .Names =
> c("vec1",
> "vec3", "d1", "d2"), row.names = 1L, class = "data.frame")
>> m      #THIS IS THE AIM
>     [,1] [,2]
> [1,]  172  223
> [2,]  173  356
> 
>> dput (m)
> structure(c(172, 173, 223, 356), .Dim = c(2L, 2L))
> 
> How can I transform jam to m?

 jam <- structure(list(vec1 = 172L, vec3 = 173L, d1 = 223L, d2 = 356L), .Names =
 c("vec1",
 "vec3", "d1", "d2"), row.names = 1L, class = "data.frame")
 jm <- data.matrix(jam)
 dim(jm) <- c(2,2) # re-dimension a matrix with column-major order
 jm

     [,1] [,2]
[1,]  172  223
[2,]  173  356

> Thanks
> Hermann
> 
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> 
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David Winsemius
Alameda, CA, USA