En Sun, 28 Dec 2008 01:47:08 -0200, Daniel Fetchinson
<fetchin...@googlemail.com> escribió:
As others already said, using a Numpy array or an array.array object
would
be more efficient (and even easier - the C code gets a pointer to an
array
of integers, as usual).
I looked for this in the C API docs but couldn't find anything on how
to make an array.array python object appear as a pointer to integers
(or floats, etc) in C code. On
http://docs.python.org/c-api/concrete.html#sequence-objects
There is only list and tuple or maybe you mean byte array? That has
only been introduced in python 2.6 and I'm working on 2.5.
array is a library module, and isn't really part of the API. You're
looking for the buffer protocol:
PyObject_AsReadBuffer/PyObject_AsWriteBuffer; see
http://docs.python.org/c-api/objbuffer.html
Given an array.array('l') (containing C long integers):
int do_something(PyObject* obj)
{
long *vec;
Py_ssize_t nbytes, nitems, i;
if (PyObject_AsReadBuffer(obj, (const void **)&vec, &nbytes) != 0)
return NULL;
nitems = nbytes/sizeof(long);
for (i=0; i<nitems; i++) {
/* do something with vec[i] */
}
return ret;
}
From Python you can get "vec" and "nitems" using the buffer_info() method
of array objects.
--
Gabriel Genellina
--
http://mail.python.org/mailman/listinfo/python-list
