dolfin team mailing list archive

["Garth N. Wells" <gnw20@xxxxxxxxx>]

Johan Hake wrote:
> On Sunday 07 March 2010 06:07:58 Garth N. Wells wrote:
>> Anders Logg wrote:
>>> On Sun, Mar 07, 2010 at 12:11:53PM +0000, Garth N. Wells wrote:
>>>> I've added the function
>>>>
>>>>   GenericVector::sum(const std::vector<uint>& rows)
>>>>
>>>> which will sum the given row entries. But, frustratingly, it doesn't
>>>> work through Python. I can't pass a list or numpy array to it. I get the
>>>> error
>>>>
>>>> TypeError: in method 'GenericVector_sum', argument 2 of type
>>>> 'std::vector< dolfin::uint > const &'
>>>>
>>>> How can I pass a list of integers to this function from Python? It seems
>>>> that we haven't resolved passing std::vector from Python to C++
>>>> satisfactorily.
>>>>
>>>> Garth
>>> Why std::vector? I thought we discussed replacing it with
>>> dolfin::Array in the interface so that it would map easily to Python
>>> which would let us remove the std::vector typemaps.
>> dolfin::Array doesn't work either.
> 
> This is because these typemaps needed to be instantiated per argument name. I 
> have now added "greedy" (argument independent) typemaps for all 
> 
>    const Array<{uint,int,double}> & foo
> 
> arguments, using the typemap macro. I guess _all_ const Array argument of the 
> above primitive types can safely be passed using NumPy arrays. It should now 
> just work for all argument names of the above types.
> 
> We still cannot do this for all Array arguments, as some might be turned into 
> an argout typemap, which needs to be treated independently. But again I do not 
> have the whole overview of these cases (if any).
> 
> It should now be possible to change all const std::vector<{uint,int,double}>& 
> foo to Array, and the above mentioned typemap should kick in.
>

Can you give an example of how it should work? I've tried

  tmp0 = numpy.array( [0, 1, 2], dtype=numpy.uint32)
  tmp1 = numpy.array( [0, 1, 2])
  tmp2 = [0, 1, 2]
  sum  = u.vector().sum(tmp0)

(with tmp0, tmp1 and tmp2), but in all cases I get:

TypeError: in method 'GenericVector_sum', argument 2 of type
'dolfin::Array< dolfin::uint > const &'

Garth

> Johan