issues: 398152613

Code Sample, a copy-pastable example if possible

This code doesn't work anymore on master.

python a = xr.DataArray(np.arange(21).reshape(3, 7), dims=['x', 'time'], coords={'x': [1, 2, 3], 'time': pd.date_range('01-01-2001', periods=7, freq='D')}) xi = xr.DataArray(np.linspace(1, 3, 50), dims=['time'], coords={'time': pd.date_range('01-01-2001', periods=50, freq='H')}) a.interp(x=xi, time=xi.time)

Problem description

The above code now raises the error

```

AttributeError Traceback (most recent call last) <ipython-input-26-dda3a6d5725b> in <module> 6 dims=['time'], 7 coords={'time': pd.date_range('01-01-2001', periods=50, freq='H')}) ----> 8 a.interp(x=xi, time=xi.time)

~/work/python/xarray/xarray/core/dataarray.py in interp(self, coords, method, assume_sorted, kwargs, coords_kwargs) 1032 ds = self._to_temp_dataset().interp( 1033 coords, method=method, kwargs=kwargs, assume_sorted=assume_sorted, -> 1034 coords_kwargs) 1035 return self._from_temp_dataset(ds) 1036

~/work/python/xarray/xarray/core/dataset.py in interp(self, coords, method, assume_sorted, kwargs, coords_kwargs) 2008 in indexers.items() if k in var.dims} 2009 variables[name] = missing.interp( -> 2010 var, var_indexers, method, kwargs) 2011 elif all(d not in indexers for d in var.dims): 2012 # keep unrelated object array

~/work/python/xarray/xarray/core/missing.py in interp(var, indexes_coords, method, *kwargs) 468 new_dims = broadcast_dims + list(destination[0].dims) 469 interped = interp_func(var.transpose(original_dims).data, --> 470 x, destination, method, kwargs) 471 472 result = Variable(new_dims, interped, attrs=var.attrs)

~/work/python/xarray/xarray/core/missing.py in interp_func(var, x, new_x, method, kwargs) 535 new_axis=new_axis, drop_axis=drop_axis) 536 --> 537 return _interpnd(var, x, new_x, func, kwargs) 538 539

~/work/python/xarray/xarray/core/missing.py in _interpnd(var, x, new_x, func, kwargs) 558 var = var.transpose(range(-len(x), var.ndim - len(x))) 559 # stack new_x to 1 vector, with reshape --> 560 xi = np.stack([x1.values.ravel() for x1 in new_x], axis=-1) 561 rslt = func(x, var, xi, **kwargs) 562 # move back the interpolation axes to the last position

~/work/python/xarray/xarray/core/missing.py in <listcomp>(.0) 558 var = var.transpose(range(-len(x), var.ndim - len(x))) 559 # stack new_x to 1 vector, with reshape --> 560 xi = np.stack([x1.values.ravel() for x1 in new_x], axis=-1) 561 rslt = func(x, var, xi, **kwargs) 562 # move back the interpolation axes to the last position

AttributeError: 'numpy.ndarray' object has no attribute 'values' ```

I think the issue is this line which returns a numpy array instead of a Variable. This was added in the coarsen PR (cc @fujiisoup) https://github.com/pydata/xarray/blob/d4c46829b283ab7e7b7db8b86dae77861ce68f3c/xarray/core/utils.py#L636