Re: [Swig-user] typemaps in R

[Bastian A. <An...@gm...>]

On Tue, 06 May 2008 05:18:04 +0200 Soeren Sonnenburg wrote:

> On Tue, 2008-05-06 at 00:50 +0200, Bastian Angermann wrote:
> > Hi,
> > 
> > the typemaps for mapping unsigned int to an appropriate type in 
> > R seem to be broken.
> 
> Yeah well R does not have anything except bool, integer, double - so
> this mapping is quite arbitrary / IMHO unclear what should be done.
> 
> > I am trying to wrap a class with constructor
> > Erdos_Renyi_Network(unsigned int ng, double af,double prob);
> > Calling network <- Erdos_Renyi_Network(ng=10,af=0.5,p=0.1) results in:
> > Error in Erdos_Renyi_Network(ng = 10, af = 0.5, p = 0.1) :
> >   REAL() can only be applied to a 'numeric', not a 'integer'
> 
> BTW, would it work when you used an int instead of an unsigned int?

Yes it is working for int. In R we have the typemap
%typemap(scoercein) int, int *, int &
  %{  $input = as($input, "integer");     %}
and on the C side of things 
INTEGER(ng)[0]

> > Could this be fixed by changing line 45,46 in rtypes.swg to
> > %typemap(scoercein) unsigned int, unsigned int *, unsigned int &
> >   %{  $input = as($input, "numeric");     %} ?
> > This removes be cast to "integer" done in R and things seem to work, 
> > but I don't know if I am introducing other bugs by this "fix".
> 
> In my eyes this cast is broken anyway... just consider $input is a
> matrix, doing as($input, ... ) will turn it into a vector. I tend to say
> that that the code doing the REAL(ng)[0] should be changed to generate a
> INTEGER(ng)[0] and that this scoercein typemap shouldn't do anythin,
> i.e. %{ %} .
> 

I don't think this will solve all problems, when going in the other direction (C->R) starting with an unsigned int => 2^31 a cast to "integer" will not have the desired result.

Bastian
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