python - xarray 的 loc API 给出 ​​KeyError：“不是在索引中找到所有值”

Question

我在使用 xarray 的 loc API 时遇到问题。我正在尝试选择满足特定条件的数据。下面应该是一个可重现的例子：

import xarray as xr
da = xr.tutorial.load_dataset('air_temperature').air
mask = 100*xr.ones_like(da[0])
da[0].loc[da[0]<mask]

但这会产生以下错误：

---------------------------------------------------------------------------
KeyError                                  Traceback (most recent call last)
<ipython-input-238-75b6b6f544d4> in <module>
      1 da = xr.tutorial.load_dataset('air_temperature').air
      2 mask = 100*xr.ones_like(da[0])
----> 3 da[0].loc[da[0]<mask]

~/miniconda3/envs/ensemble/lib/python3.7/site-packages/xarray/core/dataarray.py in __getitem__(self, key)
    194             labels = indexing.expanded_indexer(key, self.data_array.ndim)
    195             key = dict(zip(self.data_array.dims, labels))
--> 196         return self.data_array.sel(**key)
    197 
    198     def __setitem__(self, key, value) -> None:

~/miniconda3/envs/ensemble/lib/python3.7/site-packages/xarray/core/dataarray.py in sel(self, indexers, method, tolerance, drop, **indexers_kwargs)
   1045             method=method,
   1046             tolerance=tolerance,
-> 1047             **indexers_kwargs
   1048         )
   1049         return self._from_temp_dataset(ds)

~/miniconda3/envs/ensemble/lib/python3.7/site-packages/xarray/core/dataset.py in sel(self, indexers, method, tolerance, drop, **indexers_kwargs)
   1998         indexers = either_dict_or_kwargs(indexers, indexers_kwargs, "sel")
   1999         pos_indexers, new_indexes = remap_label_indexers(
-> 2000             self, indexers=indexers, method=method, tolerance=tolerance
   2001         )
   2002         result = self.isel(indexers=pos_indexers, drop=drop)

~/miniconda3/envs/ensemble/lib/python3.7/site-packages/xarray/core/coordinates.py in remap_label_indexers(obj, indexers, method, tolerance, **indexers_kwargs)
    390 
    391     pos_indexers, new_indexes = indexing.remap_label_indexers(
--> 392         obj, v_indexers, method=method, tolerance=tolerance
    393     )
    394     # attach indexer's coordinate to pos_indexers

~/miniconda3/envs/ensemble/lib/python3.7/site-packages/xarray/core/indexing.py in remap_label_indexers(data_obj, indexers, method, tolerance)
    259             coords_dtype = data_obj.coords[dim].dtype
    260             label = maybe_cast_to_coords_dtype(label, coords_dtype)
--> 261             idxr, new_idx = convert_label_indexer(index, label, dim, method, tolerance)
    262             pos_indexers[dim] = idxr
    263             if new_idx is not None:

~/miniconda3/envs/ensemble/lib/python3.7/site-packages/xarray/core/indexing.py in convert_label_indexer(index, label, index_name, method, tolerance)
    191             indexer = get_indexer_nd(index, label, method, tolerance)
    192             if np.any(indexer < 0):
--> 193                 raise KeyError("not all values found in index %r" % index_name)
    194     return indexer, new_index
    195 

KeyError: "not all values found in index 'lat'"

由于在尺寸和坐标方面mask与 xarray.DataArray 相同da，我认为这个错误没有意义......我错过了什么还是这可能是一个错误？

预先感谢您的帮助。

标签： pythonpandasindexingpython-xarray