issues: 2203250238

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id node_id number title user state locked assignee milestone comments created_at updated_at closed_at author_association active_lock_reason draft pull_request body reactions performed_via_github_app state_reason repo type
2203250238 PR_kwDOAMm_X85qh2s8 8867 Avoid in-place multiplication of a large value to an array with small integer dtype 14371165 closed 0     3 2024-03-22T20:22:22Z 2024-03-29T15:26:38Z 2024-03-29T15:26:38Z MEMBER   0 pydata/xarray/pulls/8867

Upstream numpy has become a bit more particular with which types you can use for inplace operations. This PR fixes ``` __ TestImshow.test_imshow_rgb_values_in_valid_range __

self = <xarray.tests.test_plot.TestImshow object at 0x7f88320c2780>

def test_imshow_rgb_values_in_valid_range(self) -> None:
    da = DataArray(np.arange(75, dtype="uint8").reshape((5, 5, 3)))
    _, ax = plt.subplots()

  out = da.plot.imshow(ax=ax).get_array()

/home/runner/work/xarray/xarray/xarray/tests/test_plot.py:2034:

/home/runner/work/xarray/xarray/xarray/plot/accessor.py:421: in imshow return dataarray_plot.imshow(self._da, args, kwargs) /home/runner/work/xarray/xarray/xarray/plot/dataarray_plot.py:1601: in newplotfunc primitive = plotfunc( /home/runner/work/xarray/xarray/xarray/plot/dataarray_plot.py:1853: in imshow alpha = 255

self = masked_array( data=[[[1], [1], [1], [1], [1]],

    [[1],
     [1],
...,
     [1],
     [1],
     [1],
     [1]]],

mask=False, fill_value=np.int64(999999), dtype=uint8) other = 255

def __imul__(self, other):
    """
    Multiply self by other in-place.

    """
    m = getmask(other)
    if self._mask is nomask:
        if m is not nomask and m.any():
            self._mask = make_mask_none(self.shape, self.dtype)
            self._mask += m
    elif m is not nomask:
        self._mask += m
    other_data = getdata(other)
    other_data = np.where(self._mask, other_data.dtype.type(1), other_data)

  self._data.__imul__(other_data)

E numpy._core._exceptions._UFuncOutputCastingError: Cannot cast ufunc 'multiply' output from dtype('int64') to dtype('uint8') with casting rule 'same_kind'

/home/runner/micromamba/envs/xarray-tests/lib/python3.12/site-packages/numpy/ma/core.py:4415: UFuncTypeError ```

Some curious behaviors seen while debugging: ```python alpha = np.array([1], dtype=np.int8) alpha *= 255 repr(alpha) # 'array([-1], dtype=int8)'

alpha = np.array([1], dtype=np.int16) alpha *= 255 repr(alpha) # 'array([255], dtype=int16)' ```

xref: #8844

 
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