issue_comments

I'm looking at implementing this.

I think we could do this with a simple broadcast_like on the input, as above. But is that going to miss things that our normal machinery is capturing? Currently .clip is a unary_ops which I haven't looked at in a while. And I'm not being that successful at evaluating what's going wrong from the stack trace — so posting here in case those who've worked with this recently have it cached.

One thing to note: there are different errors depending on which dimensions are missing, because of the missing broadcasting before removing the dim information:

```python

In [27]: da.clip(da.mean('a'))

ValueError Traceback (most recent call last) <ipython-input-27-c8b9c6d0e0a1> in <module> ----> 1 da.clip(da.mean('a'))

~/.asdf/installs/python/3.8.8/lib/python3.8/site-packages/xarray/core/dataarray.py in func(self, args, kwargs) 2964 ) 2965 with np.errstate(all="ignore"): -> 2966 da = self.array_wrap(f(self.variable.data, args, **kwargs)) 2967 if keep_attrs: 2968 da.attrs = self.attrs

~/.asdf/installs/python/3.8.8/lib/python3.8/site-packages/xarray/core/ops.py in func(self, args, kwargs) 228 def _method_wrapper(name): 229 def func(self, args, **kwargs): --> 230 return _call_possibly_missing_method(self, name, args, kwargs) 231 232 func.name = name

~/.asdf/installs/python/3.8.8/lib/python3.8/site-packages/xarray/core/ops.py in _call_possibly_missing_method(arg, name, args, kwargs) 214 raise 215 else: --> 216 return method(args, *kwargs) 217 218

~/.asdf/installs/python/3.8.8/lib/python3.8/site-packages/numpy/core/_methods.py in _clip(a, min, max, out, casting, kwargs) 153 um.minimum, a, max, out=out, casting=casting, kwargs) 154 elif max is None: --> 155 return _clip_dep_invoke_with_casting( 156 um.maximum, a, min, out=out, casting=casting, **kwargs) 157 else:

~/.asdf/installs/python/3.8.8/lib/python3.8/site-packages/numpy/core/_methods.py in _clip_dep_invoke_with_casting(ufunc, out, casting, args, kwargs) 110 # try to deal with broken casting rules 111 try: --> 112 return ufunc(args, out=out, **kwargs) 113 except _exceptions._UFuncOutputCastingError as e: 114 # Numpy 1.17.0, 2019-02-24

~/.asdf/installs/python/3.8.8/lib/python3.8/site-packages/xarray/core/arithmetic.py in array_ufunc(self, ufunc, method, inputs, kwargs) 68 join = dataset_join = OPTIONS["arithmetic_join"] 69 ---> 70 return apply_ufunc( 71 ufunc, 72 inputs,

~/.asdf/installs/python/3.8.8/lib/python3.8/site-packages/xarray/core/computation.py in apply_ufunc(func, input_core_dims, output_core_dims, exclude_dims, vectorize, join, dataset_join, dataset_fill_value, keep_attrs, kwargs, dask, output_dtypes, output_sizes, meta, dask_gufunc_kwargs, args) 1126 # feed DataArray apply_variable_ufunc through apply_dataarray_vfunc 1127 elif any(isinstance(a, DataArray) for a in args): -> 1128 return apply_dataarray_vfunc( 1129 variables_vfunc, 1130 args,

~/.asdf/installs/python/3.8.8/lib/python3.8/site-packages/xarray/core/computation.py in apply_dataarray_vfunc(func, signature, join, exclude_dims, keep_attrs, args) 269 270 data_vars = [getattr(a, "variable", a) for a in args] --> 271 result_var = func(data_vars) 272 273 if signature.num_outputs > 1:

~/.asdf/installs/python/3.8.8/lib/python3.8/site-packages/xarray/core/computation.py in apply_variable_ufunc(func, signature, exclude_dims, dask, output_dtypes, vectorize, keep_attrs, dask_gufunc_kwargs, *args) 741 data = as_compatible_data(data) 742 if data.ndim != len(dims): --> 743 raise ValueError( 744 "applied function returned data with unexpected " 745 f"number of dimensions. Received {data.ndim} dimension(s) but "

ValueError: applied function returned data with unexpected number of dimensions. Received 3 dimension(s) but expected 2 dimensions with names: ('b', 'c') ```

When the final dimension is missing: ```python

In [28]: da.clip(da.mean('c'))

ValueError Traceback (most recent call last) <ipython-input-28-8e46fcdf9b64> in <module> ----> 1 da.clip(da.mean('c'))

~/.asdf/installs/python/3.8.8/lib/python3.8/site-packages/xarray/core/dataarray.py in func(self, args, kwargs) 2964 ) 2965 with np.errstate(all="ignore"): -> 2966 da = self.array_wrap(f(self.variable.data, args, **kwargs)) 2967 if keep_attrs: 2968 da.attrs = self.attrs

~/.asdf/installs/python/3.8.8/lib/python3.8/site-packages/xarray/core/ops.py in func(self, args, kwargs) 228 def _method_wrapper(name): 229 def func(self, args, **kwargs): --> 230 return _call_possibly_missing_method(self, name, args, kwargs) 231 232 func.name = name

~/.asdf/installs/python/3.8.8/lib/python3.8/site-packages/xarray/core/ops.py in _call_possibly_missing_method(arg, name, args, kwargs) 214 raise 215 else: --> 216 return method(args, *kwargs) 217 218

~/.asdf/installs/python/3.8.8/lib/python3.8/site-packages/numpy/core/_methods.py in _clip(a, min, max, out, casting, kwargs) 153 um.minimum, a, max, out=out, casting=casting, kwargs) 154 elif max is None: --> 155 return _clip_dep_invoke_with_casting( 156 um.maximum, a, min, out=out, casting=casting, **kwargs) 157 else:

~/.asdf/installs/python/3.8.8/lib/python3.8/site-packages/numpy/core/_methods.py in _clip_dep_invoke_with_casting(ufunc, out, casting, args, kwargs) 110 # try to deal with broken casting rules 111 try: --> 112 return ufunc(args, out=out, **kwargs) 113 except _exceptions._UFuncOutputCastingError as e: 114 # Numpy 1.17.0, 2019-02-24

~/.asdf/installs/python/3.8.8/lib/python3.8/site-packages/xarray/core/arithmetic.py in array_ufunc(self, ufunc, method, inputs, kwargs) 68 join = dataset_join = OPTIONS["arithmetic_join"] 69 ---> 70 return apply_ufunc( 71 ufunc, 72 inputs,

~/.asdf/installs/python/3.8.8/lib/python3.8/site-packages/xarray/core/computation.py in apply_ufunc(func, input_core_dims, output_core_dims, exclude_dims, vectorize, join, dataset_join, dataset_fill_value, keep_attrs, kwargs, dask, output_dtypes, output_sizes, meta, dask_gufunc_kwargs, args) 1126 # feed DataArray apply_variable_ufunc through apply_dataarray_vfunc 1127 elif any(isinstance(a, DataArray) for a in args): -> 1128 return apply_dataarray_vfunc( 1129 variables_vfunc, 1130 args,

~/.asdf/installs/python/3.8.8/lib/python3.8/site-packages/xarray/core/computation.py in apply_dataarray_vfunc(func, signature, join, exclude_dims, keep_attrs, args) 269 270 data_vars = [getattr(a, "variable", a) for a in args] --> 271 result_var = func(data_vars) 272 273 if signature.num_outputs > 1:

~/.asdf/installs/python/3.8.8/lib/python3.8/site-packages/xarray/core/computation.py in apply_variable_ufunc(func, signature, exclude_dims, dask, output_dtypes, vectorize, keep_attrs, dask_gufunc_kwargs, args) 722 ) 723 --> 724 result_data = func(input_data) 725 726 if signature.num_outputs == 1:

ValueError: operands could not be broadcast together with shapes (2,4,3) (2,4) ```