Re: [Swig-user] (no subject)

[Will B. <wboyd@MIT.EDU>]

Thanks David! Actually, it looks like I accidentally cut out the portion of
my email which said that I know that I can use the numpy.i typemaps for
this. But unfortunately, NumPy is not available on some of the HPC clusters
that I am using. So a purely SWIG typemap for C-array-to-Python-list
conversion would be preferable. Any alternative ideas for how to do this?


On Tue, Feb 4, 2014 at 6:03 AM, David Froger <dav...@in...> wrote:

> Hi,
>
> Seems from the comment in your code that you're alread using NumPy. NumPy
> provides typemaps to convert C array to NumPy array back and forth.
>
> http://docs.scipy.org/doc/numpy/reference/swig.interface-file.html
>
> There is no typemap for array that are returned function value, but you
> could
> %inline an helper function:
>
> void get_rand_list_helper(int length, double* array);
>
> that will call get_rand_list and then wrap this helper function using
> ARGOUT_ARRAY1 typemap.
>
> The original function can be %ignore 'd (no wrapping generated for it), and
> the helper function can be %rename 'd to the original name.
>
> Hope it helps!
> David
>
> Quoting Will Boyd (2014-02-04 00:33:02)
> > Hello,
> >
> > I am trying to write a piece of code in C++ which can produce an array
> and
> > return it as as a Python list. I understand that I can return the
> >
> > The stripped down C++ routine is below:
> >
> >     /* File get_rand_list.cpp */
> >     #include "get_rand_list.h"
> >
> >     /* Define function implementation */
> >     double* get_rand_list(int length) {
> >
> >       output_list = new double[length];
> >
> >       /* Populate input NumPy array with random numbers */
> >       for (int i=0; i < length; i++)
> >         output_list[i] = ((double) rand()) / RAND_MAX;
> >
> >       return output_list;
> >     }
> >
> > I would like to be able to use this in Python as so:
> >
> >     from get_rand_list import *
> >     list = get_rand_list(10)
> >
> > How can I use SWIG typemaps to wrap the C++ routine to do this? If there
> is a
> > simpler way which requires some small modifications to the C++ routine
> that is
> > most likely fine.
> >
> > Thanks for your help,
> >
> > --
> > Will Boyd
> > Nuclear Science & Engineering
> > Massachusetts Institute of Technology
> > Email: wb...@mi...
> > Cell: 423.413.8469
>
> --
> David Froger
> SED-PRO
> "La simplicité est la sophistication suprême."
>         -- Léonard de Vinci
>



-- 
Will Boyd
Nuclear Science & Engineering
Massachusetts Institute of Technology
Email: wb...@mi...
Cell: 423.413.8469