[Numpy-discussion] [EXTERNAL] numpy.i and INPLACE_ARRAY1[ANY]

[Bill Spotz]

I think you are getting close.  Application of the typemap simply requires

    %apply (float* INPLACE_ARRAY1, int DIM1) {(float* data_location, int unused)}

rather than the entire argument list.

Be sure you understand the use case.  The (data_location, unused) pair is going to be provided by a numpy array and its length.  You might want to do a check to make sure variable "unused" has the correct value before you pass the numpy array data on to your function.

Typemaps are generally non-intuitive.  But once you understand all the rules, they start to make sense.

-Bill

On Nov 22, 2013, at 4:05 PM, Kaspar Emanuel wrote:

> Hi Bill,
> 
> thanks for your response. So the function I am actually trying to wrap is:
> 
> static inline void
> lilv_instance_connect_port(LilvInstance* instance,
>                            uint32_t      port_index,
>                            void*         data_location)
> 
> It just passes on the pointer to the data_location (the audio buffer) and then you call lilv_instance_run(int nframes) where nframes could be the dimension of your buffer, or possibly less if you really want.
> 
> So following your recommendations I tried to make a wrapper function:
> 
> lilv_instance_pyconnect(LilvInstance* instance,
>                            uint32_t      port_index,
>                            float*         data_location, int unused)
> 
> and then a typemap following what is in numpy.i :
> 
> 
> %typecheck(SWIG_TYPECHECK_DOUBLE_ARRAY,
>            fragment="NumPy_Macros")
>   (UNUSED1* UNUSED2, UNUSED3 UNUSED4, DATA_TYPE* INPLACE_ARRAY1, DIM_TYPE DIM1)
> {
>   $1 = is_array($input) && PyArray_EquivTypenums(array_type($input),
>                                                  DATA_TYPECODE);
> }
> %typemap(in,
>          fragment="NumPy_Fragments")
>   (UNUSED1* UNUSED2, UNUSED3 UNUSED4, DATA_TYPE* INPLACE_ARRAY1, DIM_TYPE DIM1)
>   (PyArrayObject* array=NULL, int i=1)
> {
>   array = obj_to_array_no_conversion($input, DATA_TYPECODE);
>   if (!array || !require_dimensions(array,1) || !require_contiguous(array)
>       || !require_native(array)) SWIG_fail;
>   $1 = (DATA_TYPE*) array_data(array);
>   $2 = 1;
>   for (i=0; i < array_numdims(array); ++i) $2 *= array_size(array,i);
> }
> 
> which I tried to apply with:
> 
> 
> %apply (LilvInstance* instance, uint32_t port_index, float* INPLACE_ARRAY1, int DIM1) {(LilvInstance* instance, uint32_t port_index, float* data_location, int unused)}
> 
> But it doesn’t seem to do anything an I just get a TypeError.
> 
> You might have noticed I am a little bit out of my depth…
> 
> Ta,
> 
> Kaspar
> 
> 
> 
> On 22 November 2013 22:40, Bill Spotz <wfspotz at sandia.gov> wrote:
> Kaspar,
> 
> Yes, in order for numpy.i typemaps to work, you need to provide dimensions.  How is lilv_test(float*) supposed to know how large the float array is?  Is it actually a method where the class knows the size?  In cases where dimensions are not passed through the argument list, you have two options:
> 
>   1. Write a proxy function that does have dimension arguments and calls the original function, and then wrap that instead of the original function.
> 
>   2. Use the functions and macros in numpy.i to write new typemaps that work for your case.
> 
> -Bill
> 
> On Nov 22, 2013, at 3:30 PM, Kaspar Emanuel wrote:
> 
> > Hey,
> > I am trying to improve the Lilv Python bindings to include numpy.i to allow for creation and verification of audio test buffers using NumPy.
> >
> > I am just trying to get something working at the moment so I am tring to wrap a test function.
> >
> > static inline void
> > lilv_test(float* data_location){}
> >
> > and I have in lilv.i:
> >
> > %apply (float* INPLACE_ARRAY1) {(float* data_location)};
> > This doesn’t produce any warnings or anything but when I try and use it from Python I get:
> >
> > TypeError: in method 'lilv_test', argument 1 of type 'float *'
> > What does work is if I have:
> >
> > lilv_test(float* data_location, int n){}
> > and
> >
> > %apply (float* INPLACE_ARRAY1, int DIM1) {(float* data_location, int n)};
> > but this doesn’t fit very well with the functions I eventually want to wrap, as they don’t have a dimension argument.
> >
> > Is it not possible to use INPLACE_ARRAY1 without a dimension?
> >
> > Thanks for any help,
> >
> > Kaspar
> >
> >
> > _______________________________________________
> > NumPy-Discussion mailing list
> > NumPy-Discussion at scipy.org
> > http://mail.scipy.org/mailman/listinfo/numpy-discussion
> 
> ** Bill Spotz                                              **
> ** Sandia National Laboratories  Voice: (505)845-0170      **
> ** P.O. Box 5800                 Fax:   (505)284-0154      **
> ** Albuquerque, NM 87185-0370    Email: wfspotz at sandia.gov **
> 
> 
> 
> 
> 
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** Bill Spotz                                              **
** Sandia National Laboratories  Voice: (505)845-0170      **
** P.O. Box 5800                 Fax:   (505)284-0154      **
** Albuquerque, NM 87185-0370    Email: wfspotz at sandia.gov **