[Numpy-discussion] problem with numpy/cython on python3, ok with python2

[Darren Dale]

I just installed numpy for both python2 and 3 from an up-to-date
checkout of the 1.5.x branch.

I am attempting to cythonize the following code with cython-0.13:

---
cimport numpy as np
import numpy as np

def test():
   cdef np.ndarray[np.float64_t, ndim=1] ret
   ret_arr = np.zeros((20,), dtype=np.float64)
   ret = ret_arr
---

I have this setup.py file:

---
from distutils.core import setup
from distutils.extension import Extension
from Cython.Distutils import build_ext

import numpy

setup(
    cmdclass = {'build_ext': build_ext},
    ext_modules = [
        Extension(
            "test_open", ["test_open.pyx"], include_dirs=[numpy.get_include()]
            )
        ]
    )
---

When I run "python setup.py build_ext --inplace", everything is fine.
When I run "python3 setup.py build_ext --inplace", I get an error:

running build_ext
cythoning test_open.pyx to test_open.c

Error converting Pyrex file to C:
------------------------------------------------------------
...
        # For use in situations where ndarray can't replace PyArrayObject*,
        # like PyArrayObject**.
        pass

    ctypedef class numpy.ndarray [object PyArrayObject]:
        cdef __cythonbufferdefaults__ = {"mode": "strided"}
                                                ^
------------------------------------------------------------

/home/darren/.local/lib/python3.1/site-packages/Cython/Includes/numpy.pxd:173:49:
"mode" is not a buffer option

Error converting Pyrex file to C:
------------------------------------------------------------
...
cimport numpy as np
import numpy as np


def test():
   cdef np.ndarray[np.float64_t, ndim=1] ret
       ^
------------------------------------------------------------

/home/darren/temp/test/test_open.pyx:6:8: 'ndarray' is not a type identifier
building 'test_open' extension
gcc -pthread -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -fPIC
-I/home/darren/.local/lib/python3.1/site-packages/numpy/core/include
-I/usr/include/python3.1 -c test_open.c -o
build/temp.linux-x86_64-3.1/test_open.o
test_open.c:1: error: #error Do not use this file, it is the result of
a failed Cython compilation.
error: command 'gcc' failed with exit status 1


Is this a bug, or is there a problem with my example?

Thanks,
Darren