R help - Oct 2009 - Matrixes as data

Hola!

I am working on a problem where data points are (square) matrices. Is
there a way to make a
"vector" of matrices, such that it can be stored in a data.frame? Can
that be done with S3?
or do I have to learn S4 objects & methods?

Kjetil

Bonjour,

On Oct 16, 2009, at 11:36 AM, Kjetil Halvorsen wrote:
> Hola!
>
> I am working on a problem where data points are (square) matrices. Is
> there a way to make a
> "vector" of matrices, such that it can be stored in a data.frame?
Can
> that be done with S3?
> or do I have to learn S4 objects & methods?
Not know anything about your problem, I'd suggest to try to think  
about your problem in terms of storing these matrices in a list. For  
example, assume you have matrices m1 to m10

my.stuff <- list(m1, m2, ..., m10)

If you can elaborate more on your specific case (or perhaps a simpler  
one that can demonstrate your use case), perhaps we can help you think  
it through a bit.

-steve

--
Steve Lianoglou
Graduate Student: Computational Systems Biology
   |  Memorial Sloan-Kettering Cancer Center
   |  Weill Medical College of Cornell University
Contact Info: http://cbio.mskcc.org/~lianos/contact

On Fri, Oct 16, 2009 at 4:36 PM, Kjetil Halvorsen
<kjetilbrinchmannhalvorsen at gmail.com> wrote:
> Hola!
>
> I am working on a problem where data points are (square) matrices. Is
> there a way to make a
> "vector" of matrices, such that it can be stored in a data.frame?
Can
> that be done with S3?
> or do I have to learn S4 objects & methods?
>
 If the matrices are all the same size then you could store them in an
array, which is essentially a 3 or more dimensional matrix.

 Otherwise, you can store them in a list, and get them by number:

foo = list(matrix(1:9,3,3),matrix(1:16,4,4))
foo[[1]]
foo[[2]]

and so forth.

You'll only need to create new object classes (with S3 or S4) if you
want special behaviour of vectors of these things (such as plot(foo)
doing something sensible).

 With S3 it's easy:

class(foo)="squareMatrixVector"

plot.squareMatrixVector=function(x,y,...){
  cat("ouch\n")
}

 plot(foo)
ouch

Barry