[Numpy-discussion] help with typemapping a C function to use numpy arrays

Egor Zindy ezindy@gmail....
Fri Jan 9 00:05:10 CST 2009


Hello Rich,

I know what you mean. %inclusion of header files saves a lot of effort! So,
I had another play with the code (what holiday this turned out to be;) and
as long as the declarations in the .i file are made in the right order, it
should be possible to:
  * %include the header file
  * %ignore a sms_ function
  * %rename the function my_ to sms_
  * %inline the my_ function

I changed the .i file (attached) and re-ran the test, it works. Again, this
is on my XP/cygwin/mingw32 system, so it could need some tuning on a
different system!

In all this, not sure where is best to put the %exception statement, but
placement shouldn't be critical, because it concerns the my_ function rather
than the original (or renamed) sms_ function.

Regards,
Egor

On Fri, Jan 9, 2009 at 5:43 AM, Rich E <reakinator@gmail.com> wrote:

> I am using %includ "sms.h", which is what is wrapping all my
> functions.  Without doing this, I have to hand-wrap every function in
> the header file!
>
> Is there a way to exclude certain definitions from my c header file
> when using %include, so that I can hand wrap them instead?
>
> On Thu, Jan 8, 2009 at 2:13 AM, Egor Zindy <ezindy@gmail.com> wrote:
> > Hello Rich,
> >
> > This is very strange. I got to test my example again, as long as you
> don't
> > do a
> > %include "dftmagnitude.h"
> > somewhere in the dftmagnitude.i, it's perfectly possible to do a
> > %rename (sms_spectrumMag) my_spectrumMag;
> > (see dftmagnitude3.zip attached in my previous mail and this one).
> >
> > So things for you to check:
> >   * does the simple dftmagnitude3.zip compile on your system?
> >   * what version of SWIG are you using? (I used 1.3.36 provided with
> cygwin)
> >   * do you have a %include statement somewhere in your own .i file?
> >
> > Matthieu, if you read this, there's a complete example provided in
> > dftmagnitude3.zip.
> >   * Wrapped function sms_spectrumMag in dftmagnitude.c and .h
> >   * SWIG wrapper dftmagnitude.i uses %inline and %rename statements
> >   * Example uses a modified numpy.i (see the previous mails in the
> thread).
> >   * test example provided in test_dftmagnitude.py
> >
> > Haven't tested it under Linux, but under winxp/cygwin/mingw32, the
> following
> > works for me (in cygwin):
> >
> > $ python setup_dftmagnitude.py build -cmingw32 ; mv
> > build/lib.win32-2.5/_dftmagnitude.pyd .
> > $ python test_dftmagnitude.py
> >
> > Regards,
> > Egor
> >
> > --
> > My Python:
> > $ python -i
> > Python 2.5.4 (r254:67916, Dec 23 2008, 15:10:54) [MSC v.1310 32 bit
> (Intel)]
> > on win32
> >
> > My SWIG:
> > $ swig -version
> >
> > SWIG Version 1.3.36
> >
> > Compiled with g++ [i686-pc-cygwin]
> > Please see http://www.swig.org for reporting bugs and further
> information
> >
> >
> >
> >
> > On Thu, Jan 8, 2009 at 1:43 AM, Rich E <reakinator@gmail.com> wrote:
> >>
> >> Here is my example, trying to wrap the function sms_spectrumMag that
> >> we have been dealing with:
> >>
> >> %apply (int DIM1, float* IN_ARRAY1) {(int sizeInArray, float*
> pInArray)};
> >> %apply (int DIM1, float* INPLACE_ARRAY1) {(int sizeOutArray, float*
> >> pOutArray)};
> >>
> >> %inline %{
> >>
> >>        void my_spectrumMag( int sizeInArray, float *pInArray, int
> >> sizeOutArray, float *pOutArray)
> >>        {
> >>                sms_spectrumMag(sizeOutArray, pInArray, pOutArray);
> >>        }
> >>
> >> %}
> >>
> >>
> >> at this point,  have the new function my_spectrumMag that wraps
> >> sms_spectrumMag() and provides arguments that can be typemapped using
> >> numpy.i  Now, I don't want to have to call the function
> >> my_spectrumMag() in python, I want to use the original name, I would
> >> like to call the function as:
> >>
> >> sms_spectrumMag(numpyArray1, numpyArray2)
> >>
> >> But, trying to %rename my_spectrumMag to sms_spectrumMag does not
> >> work, the original sms_spectrumMag gets called in python instead.
> >> Trying to %ignore the original function first as follows removes the
> >> sms_spectrumMag completely from the module and I am left with
> >> my_spectrumMag:
> >>
> >> %ignore sms_spectrumMag;
> >> %rename (sms_spectrumMag) my_spectrumMag;
> >>
> >>
> >> Do you see my problem?
> >>
> >>
> >> On Wed, Jan 7, 2009 at 8:58 AM, Matthieu Brucher
> >> <matthieu.brucher@gmail.com> wrote:
> >> > 2009/1/6 Rich E <reakinator@gmail.com>:
> >> >> This helped immensely.  I feel like I am getting close to being able
> >> >> to accomplish what I would like with SWIG: producing a python module
> >> >> that can be very 'python-like', while co-existing with the c library
> >> >> that is very 'c-like'.
> >> >>
> >> >> There is one question still remaining though, is it possible to make
> >> >> the wrapped function have the same name still?  Using either
> >> >> my_spectrumMag or spectrumMag means I have to create a number of
> >> >> inconsistencies between the python module and the c library.  It is
> >> >> ideal to ignore (%ignore?) the c sms_spectrumMag and instead use the
> >> >> wrapped one, with the same name.  But my attempts at doing this so
> far
> >> >> have not compiled because of name conflictions.
> >> >
> >> > Ok course you can. The function is renamed only if you say so. Perhaps
> >> > can you provide a small example of what doesn't work at the moment ?
> >> >
> >> >> Thanks for the help, I think you are doing great things with this
> >> >> numpy interface/typemaps system.
> >> >
> >> > Matthieu
> >> > --
> >> > Information System Engineer, Ph.D.
> >> > Website: http://matthieu-brucher.developpez.com/
> >> > Blogs: http://matt.eifelle.com and
> http://blog.developpez.com/?blog=92
> >> > LinkedIn: http://www.linkedin.com/in/matthieubrucher
> >> > _______________________________________________
> >> > Numpy-discussion mailing list
> >> > Numpy-discussion@scipy.org
> >> > http://projects.scipy.org/mailman/listinfo/numpy-discussion
> >> >
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