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BUG: Ensure __array_finalize__ cannot back-mangle shape #10314

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Merged
merged 2 commits into from
May 29, 2018
Merged

BUG: Ensure __array_finalize__ cannot back-mangle shape #10314

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BUG: Ensure __array_finalize__ cannot back-mangle shape
Jan 2, 2018
b779bae
MAINT: Replace ma.__setattr__ with dtype and shape overrides.
mhvk Mar 25, 2018
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34 changes: 27 additions & 7 deletions numpy/ma/core.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2999,7 +2999,9 @@ def __array_finalize__(self, obj):
order = "K"

_mask = _mask.astype(_mask_dtype, order)

else:
# Take a view so shape changes, etc., do not propagate back.
_mask = _mask.view()
else:
_mask = nomask

Expand Down Expand Up @@ -3344,17 +3346,35 @@ def __setitem__(self, indx, value):
_mask[indx] = mindx
return

def __setattr__(self, attr, value):
super(MaskedArray, self).__setattr__(attr, value)
if attr == 'dtype' and self._mask is not nomask:
self._mask = self._mask.view(make_mask_descr(value), ndarray)
# Try to reset the shape of the mask (if we don't have a void)
# This raises a ValueError if the dtype change won't work
# Define so that we can overwrite the setter.
@property
def dtype(self):
return super(MaskedArray, self).dtype

@dtype.setter
def dtype(self, dtype):
super(MaskedArray, type(self)).dtype.__set__(self, dtype)
if self._mask is not nomask:
self._mask = self._mask.view(make_mask_descr(dtype), ndarray)
# Try to reset the shape of the mask (if we don't have a void).
# This raises a ValueError if the dtype change won't work.
try:
self._mask.shape = self.shape
except (AttributeError, TypeError):
pass

@property
def shape(self):
return super(MaskedArray, self).shape
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@eric-wieser eric-wieser May 29, 2018 •
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Pretty sure this needs to be super(MaskedArray, type(self)).shape.__get__(self, type(self)), unless there's something weird about base classes in C

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Ok, seems there's something weird about base classes. If this were shadowing another property (rather than a getset_descriptor) , you'd need what I have above.

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I don't think that's true - I;m fairly sure one can shadow a property getter as I have it above, just not the setter.


@shape.setter
def shape(self, shape):
super(MaskedArray, type(self)).shape.__set__(self, shape)
# Cannot use self._mask, since it may not (yet) exist when a
# masked matrix sets the shape.
if getmask(self) is not nomask:
self._mask.shape = self.shape

def __setmask__(self, mask, copy=False):
"""
Set the mask.
Expand Down
4 changes: 3 additions & 1 deletion numpy/ma/tests/test_core.py
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Expand Up @@ -352,9 +352,11 @@ def test_copy(self):
assert_equal(y1._mask.__array_interface__, m.__array_interface__)

y1a = array(y1)
# Default for masked array is not to copy; see gh-10318.
assert_(y1a._data.__array_interface__ ==
y1._data.__array_interface__)
assert_(y1a.mask is y1.mask)
assert_(y1a._mask.__array_interface__ ==
y1._mask.__array_interface__)

y2 = array(x1, mask=m3)
assert_(y2._data.__array_interface__ == x1.__array_interface__)
Expand Down
6 changes: 5 additions & 1 deletion numpy/ma/tests/test_old_ma.py
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Expand Up @@ -273,7 +273,11 @@ def test_testCopySize(self):
assert_(y1.mask is m)

y1a = array(y1, copy=0)
assert_(y1a.mask is y1.mask)
# For copy=False, one might expect that the array would just
# passed on, i.e., that it would be "is" instead of "==".
# See gh-4043 for discussion.
assert_(y1a._mask.__array_interface__ ==
y1._mask.__array_interface__)

y2 = array(x1, mask=m3, copy=0)
assert_(y2.mask is m3)
Expand Down
10 changes: 10 additions & 0 deletions numpy/ma/tests/test_regression.py
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Expand Up @@ -74,3 +74,13 @@ def test_ddof_corrcoef(self):
r1 = np.ma.corrcoef(x, y, ddof=1)
# ddof should not have an effect (it gets cancelled out)
assert_allclose(r0.data, r1.data)

def test_mask_not_backmangled(self):
# See gh-10314. Test case taken from gh-3140.
a = np.ma.MaskedArray([1., 2.], mask=[False, False])
assert_(a.mask.shape == (2,))
b = np.tile(a, (2, 1))
# Check that the above no longer changes a.shape to (1, 2)
assert_(a.mask.shape == (2,))
assert_(b.shape == (2, 2))
assert_(b.mask.shape == (2, 2))