Needs tests.

Needs tests.
On 12 Oct 2013 17:26, "Marten van Kerkwijk" notifications@github.com
wrote:

Currently, masked array ufunc replacements do not check whether the ufunccall on the data proper actually works (see below). This PR ensures that
they pass on NotImplemented if needed, so that classes more interesting
than the string below will have a chance to try to do the reverse
operation.

Note that this is a long-standing bug; I'm not sure how far it can be
backported, but hope it can make 1.8.0.

p.s. The reason I stumbled upon this is that I am trying to implement a
MaskedQuantity class for astropy [1]. For this package, we already have
Unit and Quantity classes, and set it up such that array * unit returns a
Quantity; I'd hope to do have masked_array * unit similarly to return a
MaskedQuantity.

[1] http://docs.astropy.org/en/latest/units/quantity.html

In [6]: np.array([1.,2.]).mul('abc')
Out[6]: NotImplemented

In [7]: np.ma.MaskedArray([1.,2.]).mul('abc')

AttributeError Traceback (most recent call last)
in ()
----> 1 np.ma.MaskedArray([1.,2.]).mul('abc')

/usr/lib/pymodules/python2.7/numpy/ma/core.pyc in mul(self, other)
3646 def mul(self, other):
3647 "Multiply other by self, and return a new masked array."
-> 3648 return multiply(self, other)
3649 #
3650 def rmul(self, other):

/usr/lib/pymodules/python2.7/numpy/ma/core.pyc in call(self, a, b, _args, *_kwargs)
938 np.seterr(**err_status_ini)
939 # Case 1. : scalar
--> 940 if not result.ndim:
941 if m:
942 return masked

AttributeError: 'NotImplementedType' object has no attribute 'ndim'

---

You can merge this Pull Request by running

git pull https://github.com/mhvk/numpy ma/pass-on-NotImplemented

Or view, comment on, or merge it at:

#3900
Commit Summary

• Ensure NotImplemented is passed on in MaskedArray ufunc's

File Changes

• M numpy/ma/core.pyhttps://github.com/BUG Ensure NotImplemented is passed on in MaskedArray ufunc's #3900/files#diff-0(9)

Patch Links:

• https://github.com/numpy/numpy/pull/3900.patch
• https://github.com/numpy/numpy/pull/3900.diff

Needs tests.

not having contributed to numpy before, I'm not familiar with its
testing framework; should I simply add to a suitable file in the tests
subdirectory? Also, if you have it handy, could you give me a pointer to
how to set up a testing environment locally? Thanks!

Prof. M. H. van Kerkwijk
Dept. of Astronomy & Astroph., 50 St George St., Toronto, ON, M5S 3H4, Canada
McLennan Labs, room 1203B, tel: +1(416)9467288, fax: +1(416)9467287
mhvk@astro.utoronto.ca, http://www.astro.utoronto.ca/~mhvk

All you need to do is install nose. After that the easiest way to proceed is python runtests.py --help, which will tell you what to do. As to the test itself, put it in numpy/ma/test/test_core.py; use the other tests there as templates. Note that the name of the test needs to start with test_.

@charris - thanks, that probably saved me hours! Now added test cases.

Looking good, just a few issues.

This will need a backport to both 1.8.x and 1.7.x.

@charris - OK on all except the docstring -- since this would break consistency with what is done in the rest of test_core.py. If this is really better not done, I could change all the functions in a separate PR.

@charris - on the backport, do I need to do anything for that?

It's probably easier for me to do the backports unless you want the experience. The docstring thing isn't a major point and the masked arrays haven't seen much maintenance in years. If you fixup the rest of the functions in another PR, that would be great and I'll go ahead and put this in when Travis passes.

In it goes, thanks.

If you fix the docstrings it might be worth doing a PEP8 cleanup at the same time. I don't know how conformant the file is at the moment.