Add lshift and rshift operators

[abrammer]

This seems a little too easy, but the PR just adds lshift and rshit to generate_ops.py and ops.py then generated the 2 stub files with generate_ops.py.

• Closes Implement lshift and rshift operators #7727
• Tests added for:
  • xr.Variable
  • DataArray
  • dask
  • groupby
• User visible changes (including notable bug fixes) are documented in whats-new.rst
  • There will be new << >> syntax for dataarrays and datasets.
• New functions/methods are listed in api.rst
  • Existing basic math operators aren't really listed, that I can find.
  • Could add example code in the "Data arrays also implement many numpy.ndarray methods:" section of computation.rst ?

I'll wait for initial review before spending time on whats-new and api docs.

This enables bit shifting on arrays (when the type supports it).

import xarray as xr

x = xr.DataArray(5)
print(x << 1)
# <xarray.DataArray ()>
# array(10)


x = xr.DataArray([0,1,2,3,4,5])
print(x << 1)
# <xarray.DataArray (dim_0: 6)>
# array([ 0,  2,  4,  6,  8, 10])
# Dimensions without coordinates: dim_0


x = xr.DataArray([0,1,2,3,4,5])
print(x >> 1)
# <xarray.DataArray (dim_0: 6)>
# array([0, 0, 1, 1, 2, 2])
# Dimensions without coordinates: dim_0


x = xr.DataArray([0,1,2,3,4,5.])
print(x >> 1)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/workspaces/xarray/xarray/core/_typed_ops.py", line 255, in __rshift__
    return self._binary_op(other, operator.rshift)
  File "/workspaces/xarray/xarray/core/dataarray.py", line 4566, in _binary_op
    f(self.variable, other_variable)
  File "/workspaces/xarray/xarray/core/_typed_ops.py", line 461, in __rshift__
    return self._binary_op(other, operator.rshift)
  File "/workspaces/xarray/xarray/core/variable.py", line 2662, in _binary_op
    f(self_data, other_data) if not reflexive else f(other_data, self_data)
TypeError: ufunc 'right_shift' not supported for the input types, and the inputs could not be safely coerced to any supported types according to the casting rule ''safe''

[dcherian]

I don't see tests for other ops. Are these tested somewhere if so I can add tests when I find them.

Grepping for unary_op and binary_op shows a bunch in test_dataset.py, test_dataarray.py, test_variable.py

[dcherian]

I forgot to say, this looks pretty great already. We just need tests.

Thank you!

[dcherian]

LGTM. Thanks @abrammer !

[abrammer]

The commits yesterday were to add an entry to whats-new and a couple examples lines to the computation doc page. I didn't find the binary_ops listed in methods anywhere, so this was the best idea I had? In the block just above missing-values: https://xray--7741.org.readthedocs.build/en/7741/user-guide/computation.html#missing-values

Otherwise, I think this is done from my perspective.

[dcherian]

Thanks @abrammer very nice work!