Add all files to have a working example

c_code.c

+/* Small C file creating an array to demo C -> Python data passing 
+ * 
+ * Author: Gael Varoquaux
+ * License: BSD
+ */
+
+#include <stdlib.h>
+
+float *compute(int size)
+{
+    int* array;
+    array = malloc(sizeof(int)*size);
+    int i;
+    for (i=0; i<size; i++)
+    {
+	array[i] = i;
+    }
+    return array;
+}
+

cython_wrapper.pyx

+""" Small Cython file to demonstrate the use of PyArray_SimpleNewFromData
+in Cython to create an array from already allocated memory.
+
+Cython enables mixing C-level calls and Python-level calls in the same
+file with a Python-like syntax and easy type cohersion. See 
+http://cython.org for more information
+"""
+
+# Author: Gael Varoquaux
+# License: BSD
+
+# Declare the prototype of the C function we are interested in calling
+cdef extern from "c_code.c":
+    float *compute(int size)
+
+# Import the Python-level symbols of numpy
+import numpy as np
+
+# Import the C-level symbols of numpy
+cimport numpy as np
+
+# Numpy must be initialized. When using numpy from C or Cython you must
+# _always_ do that, or you will have segfaults
+np.import_array()
+
+
+def py_compute(int size):
+    """ Python binding of the 'compute' function in 'c_code.c' that does
+        not copy the data allocated in C.
+    """
+    cdef float *array
+    # Call the C function
+    array = compute(size)
+
+    # Create a C array to describe the shape of the ndarray
+    cdef np.npy_intp shape[1]
+    shape[0] = <np.npy_intp> size
+
+    # Use the PyArray_SimpleNewFromData function from numpy to create a
+    # new Python object pointing to the existing data
+    ndarray = np.PyArray_SimpleNewFromData(1, shape,
+                    np.NPY_INT, <void *> array)
+    return ndarray

setup.py

+""" Example of building a module with a Cython file. See the distutils
+and numpy distutils documentations for more info:
+http://docs.scipy.org/doc/numpy/reference/distutils.html
+"""
+# Author: Gael Varoquaux
+# License: BSD
+
+import numpy
+from Cython.Distutils import build_ext
+
+def configuration(parent_package='', top_path=None):
+    """ Function used to build our configuration.
+    """
+    from numpy.distutils.misc_util import Configuration
+
+    # The configuration object that hold information on all the files
+    # to be built.
+    config = Configuration('', parent_package, top_path)
+    config.add_extension('cython_wrapper',
+                         sources=['cython_wrapper.pyx'],
+                         # libraries=['m'],
+                         depends=['c_code.c'],
+                         include_dirs=[numpy.get_include()])
+    return config
+
+
+if __name__ == '__main__':
+    # Retrieve the parameters of our local configuration
+    params = configuration(top_path='').todict()
+
+    # Override the C-extension building so that it knows about '.pyx'
+    # Cython files
+    params['cmdclass'] = dict(build_ext=build_ext)
+
+    # Call the actual building/packaging function (see distutils docs)
+    from numpy.distutils.core import setup
+    setup(**params)