[Numpy-discussion] Extending C with Python

[Chris Barker]

I'm guessing you could use Cython to make this easier. It's usually used
for calling C from Python, but can do the sandwich in both directions...

Just a thought -- it will help with some of that boilerplate code...

-CHB




On Tue, Jan 30, 2018 at 10:57 PM, Jialin Liu <jalnliu at lbl.gov> wrote:

> Amazing! It works! Thank you Robert.
>
> I've been stuck with this many days.
>
> Best,
> Jialin
> LBNL/NERSC
>
> On Tue, Jan 30, 2018 at 10:52 PM, Robert Kern <robert.kern at gmail.com>
> wrote:
>
>> On Wed, Jan 31, 2018 at 3:25 PM, Jialin Liu <jalnliu at lbl.gov> wrote:
>>
>>> Hello,
>>> I'm extending C with python (which is opposite way of what people
>>> usually do, extending python with C), I'm currently stuck in passing a C
>>> array to python layer, could anyone plz advise?
>>>
>>> I have a C buffer in my C code and want to pass it to a python function.
>>> In the C code, I have:
>>>
>>> npy_intp  dims [2];
>>>> dims[0] = 10;
>>>> dims[1] = 20;
>>>> import_array();
>>>> npy_intp m=2;
>>>> PyObject * py_dims = PyArray_SimpleNewFromData(1, &m, NPY_INT16 ,(void
>>>> *)dims ); // I also tried NPY_INT
>>>> PyObject_CallMethod(pInstance, method_name, "O", py_dims);
>>>
>>>
>>> In the Python code, I want to just print that array:
>>>
>>> def f(self, dims):
>>>
>>>    print ("np array:%d,%d"%(dims[0],dims[1]))
>>>
>>>
>>>
>>> But it only prints the first number correctly, i.e., dims[0]. The second
>>> number is always 0.
>>>
>>
>> The correct typecode would be NPY_INTP.
>>
>> --
>> Robert Kern
>>
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>>
>
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Christopher Barker, Ph.D.
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