ENH: set correct __module__ for objects in numpy's public API

Fixes GH-12271

Tests verify that everything in ``dir(numpy)`` either has ``__module__`` set to
``'numpy'``, or appears in an explicit whitelist of undocumented functions and
exported bulitins. These should eventually be documented or removed.

I also identified a handful of functions for which I had accidentally not setup
dispatch for with ``__array_function__`` before, because they were listed under
"ndarray methods" in ``_add_newdocs.py``. I guess that should be a lesson in
trusting code comments :).

1 files changed, 3 insertions, 2 deletions

diff --git a/numpy/fft/helper.py b/numpy/fft/helper.py
index e65883651..864768df5 100644
--- a/numpy/fft/helper.py
+++ b/numpy/fft/helper.py
@@ -11,7 +11,7 @@ except ImportError:
     import dummy_threading as threading
 from numpy.compat import integer_types
 from numpy.core import integer, empty, arange, asarray, roll
-from numpy.core.overrides import array_function_dispatch
+from numpy.core.overrides import array_function_dispatch, set_module
 
 # Created by Pearu Peterson, September 2002
 
@@ -128,6 +128,7 @@ def ifftshift(x, axes=None):
     return roll(x, shift, axes)
 
 
+@set_module('numpy.fft')
 def fftfreq(n, d=1.0):
     """
     Return the Discrete Fourier Transform sample frequencies.
@@ -174,9 +175,9 @@ def fftfreq(n, d=1.0):
     p2 = arange(-(n//2), 0, dtype=int)
     results[N:] = p2
     return results * val
-    #return hstack((arange(0,(n-1)/2 + 1), arange(-(n/2),0))) / (n*d)
 
 
+@set_module('numpy.fft')
 def rfftfreq(n, d=1.0):
     """
     Return the Discrete Fourier Transform sample frequencies