Re: Boost python : get the shape of a numpy ndarray in C++ code.

[Roman Yakovenko]

On 9 May 2007 08:08:46 -0700, TG <[EMAIL PROTECTED]> wrote:
> Hi there.
>
> I'm strugling here with some boost python code (damn I hate C++) :
>
> All I want to do is to initialize the content of an array with a numpy
> ndarray parameter. I have this, which actually works. But I want to
> add some kind of data check such as :
>
> * is array two dimensional ?

This question has nothing to do with Boost.Python

> * are the dimensions corresponding to map's width / height ?

Same as above

> * is array field with floats or ints ?

Read "extract" documentation http://boost.org/libs/python/doc/v2/extract.html

> void
> Layer::set_potentials (numeric::array& array)
> {
>   for (int h=0; hheight; h++){
> for (int w=0; wwidth; w++){
>   units[w+h*map->width]->potential =
> extract(array[make_tuple(w,h)]);
> }
>   }
> }
>
>
> Some help is very welcome here ... thanks.
>
> --
> http://mail.python.org/mailman/listinfo/python-list
>


-- 
Roman Yakovenko
C++ Python language binding
http://www.language-binding.net/
-- 
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Re: Boost python : get the shape of a numpy ndarray in C++ code.

[TG]

What I'm trying to say here : a numpy array is supposed to have it's
shape stored as a tuple. What I want to do is to access this
information from my C++ code, in order to do some validity check.

So, by looking around in the doc of boost/python/numeric.hpp I was
able to do this :

void
Layer::set_potentials (numeric::array& array)
{
  for (int h=0; hheight; h++){
for (int w=0; wwidth; w++){
  units[w+h*map->width]->potential =
extract(array[make_tuple(w,h)]);
}
  }
}

which is fairly simple and actually works. Now, if I look further, I
see there is a method called getshape() in array class, which gives
back an object - I guess this object is a tuple, because the
documentation is quite poor.

So my idea is to get this object and use extract in order to get the
actual dimensions as integers.

but when I add this :

void
Layer::set_potentials (numeric::array& array)
{
  object shape = array.getshape();

  [...]
}

It compiles, and then on execution I get this error :

AttributeError: 'numpy.ndarray' object has no attribute 'getshape'

Does it still have nothing to do with Boost.Python ?

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