[Numpy-discussion] Numpy extension writing problems
Jeremy Sanders
jeremy@jeremysanders....
Thu Sep 24 03:50:22 CDT 2009
Hi - I've never written a Python extension before, so I apologise in advance
for my lack of knowledge. I'm trying to interpret a variable length tuple of
variable length numpy arrays, convert then to C double arrays and pass them
to a C++ function. I'm using SIP (as I also need to deal with Qt).
Here is my rather poor code(I realise that variable length C arrays on the
stack are a gcc extension). a0 is the PyObject* for the tuple. It core dumps
on PyArray_AsCArray.
%MethodCode
const Py_ssize_t numitems = PyTuple_Size(a0);
double* data[numitems];
int sizes[numitems];
PyObject* objects[numitems];
int status = 0;
PyArray_Descr *descr = PyArray_DescrFromType(PyArray_DOUBLE);
for(Py_ssize_t i = 0; i != numitems; i++)
data[i] = NULL;
if( ! PyTuple_Check(a0) )
goto exit;
for(Py_ssize_t i = 0; i != numitems; i++)
{
objects[i] = PyTuple_GetItem(a0, i);
npy_intp size;
int ret = PyArray_AsCArray(&objects[i], (void*)(&data[i]),
&size, 1, descr);
if(ret < 0)
{
status = 1;
goto exit;
}
sizes[i] = size;
}
// this is the actual function to call
TestKlass::myfunc(data, sizes, numitems);
exit:
for(Py_ssize_t i = 0; i != numitems; i++)
{
if( data[i] != NULL )
{
PyArray_Free(objects[i], data[i]);
}
}
if(status != 0)
{
PyErr_SetString(PyExc_RuntimeError, "conversion error");
sipIsErr = 1;
}
%End
Can someone give me a hint on where I'm going wrong? Can't I pass
PyTuple_GetItem objects to PyArray_AsCArray. Is there a numpy built in
routine which makes this easier?
Thanks
Jeremy
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