If you rename the quacker.pyx to quacker.py, everything is actually correct. The only problem is that your program won’t search for python modules in the current directory, resulting in the output: Exception NameError: “name ‘quack’ is not defined” in ‘caller.call_quack’ ignored If you add the current directory to the PYTHONPATH environment variable however, the output … Read more
You should consider Boost.Python if you are not planning to generate bindings for other languages as well with swig. If you have a lot of functions and classes to bind, Py++ is a great tool that automatically generates the needed code to make the bindings. Pybindgen may also be an option, but it’s a new … Read more
I was able to get a solution working for Python 2.x a lot easier than Python 3.x. For whatever reason, Cython seems to be caching the shareable object (.so) file it imports your module from, and even after rebuilding and deleting the old file while running, it still imports from the old shareable object file. … Read more
As we will see the behavior is dependent on which numpy-distribution is used. This answer will focus on Anacoda-distribution with Intel’s VML (vector math library), millage can vary given another hardware and numpy-version. It will also be shown, how VML can be utilized via Cython or numexpr, in case one doesn’t use Anacoda-distribution, which plugs-in … Read more
Create a helper array in cython To get a double** from a numpy array, you can create a helper-array of pointers in your *.pyx file. Further more, you have to make sure that the numpy array has the correct memory layout. (It might involve creating a copy) Fortran order If your C-function expects fortran order … Read more
Try following code. to_cstring_array function in the following code is what you want. from libc.stdlib cimport malloc, free from libc.string cimport strcmp from cpython.string cimport PyString_AsString cdef char ** to_cstring_array(list_str): cdef char **ret = <char **>malloc(len(list_str) * sizeof(char *)) for i in xrange(len(list_str)): ret[i] = PyString_AsString(list_str[i]) return ret def foo(list_str1, list_str2): cdef unsigned int i, … Read more
I’m not going to answer all your questions, but only (in my eyes) the most interesting ones. Let start with your counting example: the compiler is able to optimize the for-loop in the integer-case – the resulting binary doesn’t not calculate anything – it only hast to return the value precalculated during the compilation phase. … Read more
The code is found in the original pyx-file next to your exe. Delete/don’t distribute this pyx-file with your exe. When you look at the generated C-code, you will see why the error message is shown by your executable: For a raised error, Cython will emit a code similar to the following: __PYX_ERR(0, 11, __pyx_L3_error) where … Read more
I think @FlorianWeimer’s answer provides a decent solution (allocate a vector and pass that into your C++ function) but it should be possible to return a vector from doit and avoid copies by using the move constructor. from libcpp.vector cimport vector cdef extern from “<utility>” namespace “std” nogil: T move[T](T) # don’t worry that this … Read more
Py_ssize_t is signed. See PEP 353, where it says “A new type Py_ssize_t is introduced, which has the same size as the compiler’s size_t type, but is signed. It will be a typedef for ssize_t where available.” You should use Py_ssize_t for indexing. I didn’t find a definitive statement of this in the Cython docs, … Read more