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charrischarris
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Merge pull request #32477 from charris/backport-32423
BUG: fix stale fill_value after ufuncs change MaskedArray dtype (#32423)
2 parents 86c83ed + fc5820e commit ab1b589

3 files changed

Lines changed: 76 additions & 3 deletions

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‎doc/release/upcoming_changes/32423.change.rst‎

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,8 @@
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`MaskedArray._fill_value` would become stale when ufuncs that change dtype
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left the result holding a fill_value typed for the old dtype. The mismatch
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was silent until something later called `_check_fill_value`, such as
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`.view()`, and then a `TypeError` would be raised. Now, when the copied
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fill_value is no longer valid for the new dtype, fall back to the
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default fill_value for that dtype instead of propagating the stale value.
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This can now raise a `ComplexWarning` if the fill_value is complex and the
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new dtype is real.

‎numpy/ma/core.py‎

Lines changed: 7 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -3037,7 +3037,13 @@ def _update_from(self, obj):
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_optinfo.update(getattr(obj, '_basedict', {}))
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if not isinstance(obj, MaskedArray):
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_optinfo.update(getattr(obj, '__dict__', {}))
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_dict = {'_fill_value': getattr(obj, '_fill_value', None),
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_fill_value = getattr(obj, '_fill_value', None)
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if _fill_value is not None and getattr(obj, 'dtype', None) != self.dtype:
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try:
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_fill_value = _check_fill_value(_fill_value, self.dtype)
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except (TypeError, ValueError, OverflowError):
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_fill_value = None
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_dict = {'_fill_value': _fill_value,
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'_hardmask': getattr(obj, '_hardmask', False),
30423048
'_sharedmask': getattr(obj, '_sharedmask', False),
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'_isfield': getattr(obj, '_isfield', False),

‎numpy/ma/tests/test_core.py‎

Lines changed: 61 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1285,8 +1285,11 @@ def test_basic_ufuncs(self):
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assert_equal(np.arctan(z), arctan(zm))
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assert_equal(np.arctan2(x, y), arctan2(xm, ym))
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assert_equal(np.absolute(x), absolute(xm))
1288-
assert_equal(np.angle(x + 1j * y), angle(xm + 1j * ym))
1289-
assert_equal(np.angle(x + 1j * y, deg=True), angle(xm + 1j * ym, deg=True))
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# Complex fill_value becomes real, raising ComplexWarning
1289+
with pytest.warns(np.exceptions.ComplexWarning):
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assert_equal(np.angle(x + 1j * y), angle(xm + 1j * ym))
1291+
with pytest.warns(np.exceptions.ComplexWarning):
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assert_equal(np.angle(x + 1j * y, deg=True), angle(xm + 1j * ym, deg=True))
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assert_equal(np.equal(x, y), equal(xm, ym))
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assert_equal(np.not_equal(x, y), not_equal(xm, ym))
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assert_equal(np.less(x, y), less(xm, ym))
@@ -2625,6 +2628,62 @@ def test_fillvalue_in_view(self):
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y = x.view(dtype=np.int32)
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assert_(y.fill_value == 999999)
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def test_fillvalue_reset_after_dtype_changing_ufunc(self):
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# Test that a fill_value which no longer matches the dtype of the
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# result of a ufunc (because the ufunc changed the dtype) is reset
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# to the default for the new dtype.
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a = array(['foo', 'bar', 'baz'], mask=False, fill_value='N/A')
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result = np.strings.find(a, 'foo')
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2638+
# np.strings.find returns the platform default int dtype
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assert_(result.dtype.kind == 'i')
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assert_equal(result.fill_value, default_fill_value(result.dtype))
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assert_equal(result.filled().dtype, result.dtype)
2642+
2643+
viewed = result.view(MaskedArray)
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assert_equal(viewed.fill_value, default_fill_value(result.dtype))
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2646+
def test_fillvalue_castable_after_dtype_changing_ufunc(self):
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# Test that fill_values that *can* be cast into the new dtype.
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# The cast value should be kept rather than being reset to the default,
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# and .filled() should not be forced to fall back to `object` dtype.
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a = array(['ab', 'cd'], mask=[0, 1], fill_value='-1')
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result = np.strings.find(a, 'a')
2652+
assert_(result.dtype.kind == 'i')
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assert_equal(result.fill_value, -1)
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assert_equal(result.filled(), [0, -1])
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assert_equal(result.filled().dtype, result.dtype)
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2657+
x = array([1.5, np.nan, 2.5], mask=[0, 0, 1], fill_value=1e20)
2658+
y = np.isnan(x)
2659+
assert_equal(y.dtype, np.dtype(bool))
2660+
assert_equal(y.fill_value, True)
2661+
assert_equal(y.filled(), [False, True, True])
2662+
assert_equal(y.filled().dtype, y.dtype)
2663+
2664+
d = array(np.array(['2020-01-01', '2020-01-02'], 'M8[D]'), mask=[0, 1])
2665+
d.set_fill_value(np.datetime64('NaT', 'D'))
2666+
z = d - np.datetime64('2020-01-01', 'D')
2667+
assert_equal(z.dtype, np.dtype('timedelta64[D]'))
2668+
assert_(np.isnat(z.fill_value))
2669+
assert_equal(z.filled().dtype, z.dtype)
2670+
2671+
# the fill_value's complex dtype is cast into the new real dtype
2672+
c = array([1 + 1j, 2j], mask=[0, 1], fill_value=2 + 3j)
2673+
with pytest.warns(np.exceptions.ComplexWarning):
2674+
r = np.abs(c)
2675+
assert_equal(r.dtype, np.dtype(float))
2676+
assert_equal(r.fill_value, 2.0)
2677+
assert_equal(r.filled().dtype, r.dtype)
2678+
2679+
# a fill_value that overflows the new dtype during the cast
2680+
wide = np.dtype([('id', object)])
2681+
narrow = np.dtype([('id', 'i8')])
2682+
e = array([(1,), (2,)], dtype=wide, mask=[0, 1], fill_value=(10 ** 30,))
2683+
f = e.astype(narrow)
2684+
assert_equal(f.fill_value, default_fill_value(narrow))
2685+
assert_equal(f.filled().dtype, f.dtype)
2686+
26282687
def test_fillvalue_bytes_or_str(self):
26292688
# Test whether fill values work as expected for structured dtypes
26302689
# containing bytes or str. See issue #7259.

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