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

[Kaspar Emanuel]

Cool! That seems to have worked. Many thanks. So I didn't need my own
typemap for this at all as it will already ignore the rest of the
arguments?

What I still don't understand is that there seems to be a typemap for
INPLACE_ARRAY1[ANY] without any DIM1. How come I can't apply that?

 > 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.

The only point where the check could be made would be in the run
function which should not be run with a value longer than the array
length.


On 22 November 2013 23:19, Bill Spotz <wfspotz at sandia.gov> wrote:
> 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
>> >
>> >
>> > _______________________________________________
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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 **
>>
>>
>>
>>
>>
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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 **
>
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