python-extensions

I'm trying to write Cython code to dump a dense feature matrix, target vector pair to libsvm format faster than sklearn's built in code. I get a compilation error complaining about a type issue with passing the target vector (a numpy array of ints) to the relevant c function. Here's the code: import numpy as np cimport numpy as np cimport cython cdef extern from "cdump.h": int filedump( double features[], int numexemplars, int numfeats, int target[], char* outfname) @cython.boundscheck(False) @cython.wraparound(False) def fastdumpdense_libsvmformat(np.ndarray[np.double_t,ndim=2] X, y, outfname

Last edit: I've figured out what the problem was (see my own answer below) but I cannot mark the question as answered, it would seem. If someone can answer the questions I have in my answer below, namely, is this a bug in Cython or is this Cython's intended behavior, I will mark that answer as accepted, because that would be the most useful lesson to gain from this, IMHO. Firstly, I have to start by saying that I have been trying to figure this out for three days, and I am just banging my head against the wall. As best as I can tell from the documentation, I am doing things correctly.

I have Python extension module written in C. I want to use in this C code one of the standard Python modules, for example os or shutil . How is best to do this? PyObject* os = PyImport_ImportModuleNoBlock("os"); if (os == NULL) return NULL; someattr = PyObject_GetAttrString(os, "someattr"); Py_DECREF(os); If you import the module only once e.g., in init_yourmodule() function then use PyImport_ImportModule("os") . Don't. Instead, change your extension module so that it provides a service to Python, and then write Python code which calls os , shutil and your module. In fact, for a lot of the

The Python community has published helpful reference material showing how to profile Python code, and the technical details of Python extensions in C or in Cython . I am still searching for tutorials which show, however, for non-trivial Python programs, the following: How to identify the hotspots which will benefit from optimization by conversion to a C extension Just as importantly, how to identify the hotspots which will not benefit from conversion to a C extension Finally, how to make the appropriate conversion from Python to C, either using the Python C-API or (perhaps even preferably)

I am attempting to write a C extension for python. With the code (below) I get the compiler warning: implicit declaration of function ‘Py_InitModule’ And it fails at run time with this error: undefined symbol: Py_InitModule I have spent literally hours searching for a solution with no joy. I have tried multiple minor changes to syntax, I even found a post suggesting the method has been deprecated. However I find no replacement. Here is the code: #include <Python.h> //a func to calc fib numbers int cFib(int n) { if (n<2) return n; return cFib(n-1) + cFib(n-2); } static PyObject* fib(PyObject*

Possible Duplicate: Any AOP support library for Python? I am familiar with the AspectJ extension for the Java language. I want to know if there is such a thing for Python. Don't get me wrong, I do not mean a library but a language extension like AspectJ is to Java. jsbueno Python does not need something like a "language extension" for being able to work in an Aspect Oriented way. That is simply due to the dynamic mechanisms in Python itself. A Google search will yield a couple projects - but despite looking merely like libraries, it is all that is needed in Python. I am not making this up - it

I have just compiled part of my C library as an extension using Cython, as a "proof of concept". I managed to hack the code (const correctnes problems etc aside), to finally get an extension built. However, when I attempted to import the newly created extension, I got the following error: ImportError: dynamic module does not define init function What am I doing wrong and how do I fix this? I am using Cythn 0.11.2 and Python 2.6.5 on Ubuntu 10.0.4 I've found that a frequent cause of this problem is, when using a distutils setup file to compile the code, that the .pyx base name does not match