[R] FW: S4 classes, creating in C

[Duncan Temple Lang]

I don't believe the fact that you are doing this in C code is relevant
in this problem. 

If you define LUdecomposition as
 setClass("LUdecomposition", representation(a="matrix", pivot = "integer"),
                             prototype=list(pivot = NA)                    )


you will get an error if you simply type

  new("LUdecomposition")


To make this work,  define the class as

 setClass("LUdecomposition", representation(a="matrix", pivot = "integer"),
                             prototype=list(pivot = as.integer(NA)                    ))

Why the original does not work is because 
  typeof(NA) 
returns "logical".
So it is merely the type of the value that is the problem.

 HTH,
  Duncan


Douglas Bates wrote:
> Laurence Kell FM CEFAS <L.T.Kell at cefas.co.uk> writes:
> 
> >  
> >  I am using C code to create an S4 object based on Douglas Bates's example
> > in his lecture notes on
> > <http://www.ci.tuwien.ac.at/Conferences/DSC-2003/Tutorials/RExtensions/slide
> > s.pdf>
> > http://www.ci.tuwien.ac.at/Conferences/DSC-2003/Tutorials/RExtensions/slides
> > .pdf
> > 
> > e.g.
> > 
> > SEXP La_DGE_dc(SEXP A)
> >         {
> >         SEXP aa = PROTECT(duplicate(A));
> >         SEXP adims, pivot, val;
> >         int m, n, info;
> >        
> >         if (!isMatrix(aa) || !isReal(aa)) {
> >                 error("A must be a double precision matrix");
> >                 }
> > 
> >         adims = GET_DIM(aa); m = INTEGER(adims)[0]; n = INTEGER(adims)[1];
> >         pivot = PROTECT(NEW_INTEGER(m < n ? m : n));
> > 
> >         F77_CALL(dgetrf)(&m, &n, REAL(aa), &m, INTEGER(pivot), &info);
> >        
> >         check_Lapack_error(info, "dtrtrf");
> >        
> >         val = PROTECT(NEW_OBJECT(MAKE_CLASS("LUdecomposition")));
> > 
> >         SET_SLOT(val, install("a"), aa);
> >         SET_SLOT(val, install("pivot"), pivot);
> >        
> >         UNPROTECT(3);
> >         return val;
> >         }
> > 
> > LUdecomposition is an S4 class defined as
> > 
> > setClass("LUdecomposition", representation(a="matrix", pivot = "integer"))
> > 
> > This works in R 1.7.0 and R 1.7.1 but if I initialise any of the slots
> > 
> > setClass("LUdecomposition", representation(a="matrix", pivot = "integer"),
> >                             prototype=list(pivot = NA)                    )
> > 
> > then I get the following error message in R 1.7.1 but not R 1.7.0
> > 
> > Error in makePrototypeFromClassDef(properties, ClassDef, immediate) :
> >         In making the prototype for class "LUdecomposition" elements of the
> > prototype
> >         failed to match the corresponding slot class: pivot (class " integer
> > ")
> > 
> > Why  can I no longer use the prototype to set the default values?
> 
> I'm not sure.  This may be the type of question that requires John
> Chambers' attention and I think he is away from his email this week.
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
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-- 
_______________________________________________________________

Duncan Temple Lang                duncan at research.bell-labs.com
Bell Labs, Lucent Technologies    office: (908)582-3217
700 Mountain Avenue, Room 2C-259  fax:    (908)582-3340
Murray Hill, NJ  07974-2070       
         http://cm.bell-labs.com/stat/duncan