better mappers draft

cf_xarray/accessor.py

@@ -372,36 +372,46 @@ def _get_with_standard_name(
     return varnames
 
 
+def _get_all(obj: Union[DataArray, Dataset], key: Union[str, List[str]]) -> List[str]:
+    all_mappers = (_get_axis_coord, _get_measure, _get_with_standard_name, _get_measure)
+    results = apply_mapper(all_mappers, obj, key, error=False, default=None)
+    return results
+
+
+def _get_dims(obj: Union[DataArray, Dataset], key: Union[str, List[str]]):
+    return [k for k in _get_all(obj, key) if k in obj.dims]
+
+
+def _get_indexes(obj: Union[DataArray, Dataset], key: Union[str, List[str]]):
+    return [k for k in _get_all(obj, key) if k in obj.indexes]
+
+
+def _get_coords(obj: Union[DataArray, Dataset], key: Union[str, List[str]]):
+    return [k for k in _get_all(obj, key) if k in obj.coords]
+
+
 #: Default mappers for common keys.
 _DEFAULT_KEY_MAPPERS: Mapping[str, Tuple[Mapper, ...]] = {
-    "dim": (_get_axis_coord, _get_with_standard_name),
-    "dims": (_get_axis_coord, _get_with_standard_name),  # transpose
-    "drop_dims": (_get_axis_coord, _get_with_standard_name),  # drop_dims
-    "dimensions": (_get_axis_coord, _get_with_standard_name),  # stack
-    "dims_dict": (_get_axis_coord, _get_with_standard_name),  # swap_dims, rename_dims
-    "shifts": (_get_axis_coord, _get_with_standard_name),  # shift, roll
-    "pad_width": (_get_axis_coord, _get_with_standard_name),  # shift, roll
-    "names": (
-        _get_axis_coord,
-        _get_measure,
-        _get_with_standard_name,
-    ),  # set_coords, reset_coords, drop_vars
-    "labels": (_get_axis_coord, _get_measure, _get_with_standard_name),  # drop
-    "coords": (_get_axis_coord, _get_with_standard_name),  # interp
-    "indexers": (_get_axis_coord, _get_with_standard_name),  # sel, isel, reindex
+    "dim": (_get_dims,),  # (_get_axis_coord, _get_with_standard_name),
+    "dims": (_get_dims,),  # (_get_axis_coord, _get_with_standard_name),  # transpose
+    "drop_dims": (_get_dims,),  # drop_dims
+    "dimensions": (_get_dims,),  # stack
+    "dims_dict": (_get_dims,),  # swap_dims, rename_dims
+    "shifts": (_get_dims,),  # shift, roll
+    "pad_width": (_get_dims,),  # shift, roll
+    "names": (_get_all,),  # set_coords, reset_coords, drop_vars
+    "labels": (_get_indexes,),  # drop_sel
+    "coords": (_get_dims,),  # interp
+    "indexers": (_get_indexes,),  # sel, isel, reindex
     # "indexes": (_get_axis_coord,),  # set_index
-    "dims_or_levels": (_get_axis_coord, _get_with_standard_name),  # reset_index
-    "window": (_get_axis_coord, _get_with_standard_name),  # rolling_exp
+    "dims_or_levels": (_get_dims,),  # reset_index
+    "window": (_get_dims,),  # rolling_exp
     "coord": (_get_axis_coord_single,),  # differentiate, integrate
-    "group": (
-        _get_axis_coord_single,
-        _get_groupby_time_accessor,
-        _get_with_standard_name,
-    ),
-    "indexer": (_get_axis_coord_single,),  # resample
-    "variables": (_get_axis_coord, _get_with_standard_name),  # sortby
+    "group": (_get_all, _get_groupby_time_accessor),  # groupby
+    "indexer": (_get_indexes,),  # resample
+    "variables": (_get_all,),  # sortby
     "weights": (_get_measure_variable,),  # type: ignore
-    "chunks": (_get_axis_coord, _get_with_standard_name),  # chunk
+    "chunks": (_get_dims,),  # chunk
 }
 
 
@@ -430,13 +440,20 @@ def _build_docstring(func):
     can be used for arguments.
     """
 
+    get_all_docstring = (
+        f"One or more of {(_AXIS_NAMES + _COORD_NAMES)!r};\n\t\t\tor standard names"
+    )
     # this list will need to be updated any time a new mapper is added
     mapper_docstrings = {
         _get_axis_coord: f"One or more of {(_AXIS_NAMES + _COORD_NAMES)!r}",
         _get_axis_coord_single: f"One of {(_AXIS_NAMES + _COORD_NAMES)!r}",
         _get_groupby_time_accessor: "Time variable accessor e.g. 'T.month'",
         _get_with_standard_name: "Standard names",
         _get_measure_variable: f"One of {_CELL_MEASURES!r}",
+        _get_all: get_all_docstring,
+        _get_indexes: get_all_docstring + "present in .indexes",
+        _get_dims: get_all_docstring + "present in .dims",
+        _get_coords: get_all_docstring + "present in .coords",
     }
 
     sig = inspect.signature(func)
@@ -1374,6 +1391,12 @@ def guess_coord_axis(self, verbose: bool = False) -> Union[DataArray, Dataset]:
                     obj[var].attrs = dict(ChainMap(obj[var].attrs, ATTRS[axis]))
         return obj
 
+    def drop(self, *args, **kwargs):
+        raise NotImplementedError(
+            "cf-xarray does not support .drop."
+            "Please use .cf.drop_vars or .cf.drop_sel as appropriate."
+        )
+
 
 @xr.register_dataset_accessor("cf")
 class CFDatasetAccessor(CFAccessor):

cf_xarray/tests/test_accessor.py

@@ -849,8 +849,7 @@ def test_standard_name_mapper():
 
 
 @pytest.mark.parametrize("obj", objects)
-@pytest.mark.parametrize("attr", ["drop", "drop_vars", "set_coords"])
-@pytest.mark.filterwarnings("ignore:dropping .* using `drop` .* deprecated")
+@pytest.mark.parametrize("attr", ["drop_vars", "set_coords"])
 def test_drop_vars_and_set_coords(obj, attr):
 
     # DataArray object has no attribute set_coords

doc/whats-new.rst

@@ -9,7 +9,7 @@ v0.4.1 (unreleased)
 - Replace ``cf.describe()`` with :py:meth:`Dataset.cf.__repr__`. By `Mattia Almansi`_.
 - Automatically set ``x`` or ``y`` for :py:attr:`DataArray.cf.plot`. By `Deepak Cherian`_.
 - Added scripts to document :ref:`criteria` with tables. By `Mattia Almansi`_.
-- Support for ``.drop()``, ``.drop_vars()``, ``.drop_sel()``, ``.drop_dims()``, ``.set_coords()``, ``.reset_coords()``. By `Mattia Almansi`_.
+- Support for ``.drop_vars()``, ``.drop_sel()``, ``.drop_dims()``, ``.set_coords()``, ``.reset_coords()``. By `Mattia Almansi`_.
 - Support for using ``standard_name`` in more functions. (:pr:`128`) By `Deepak Cherian`_
 - Allow :py:meth:`DataArray.cf.__getitem__` with standard names. By `Deepak Cherian`_
 - Rewrite the ``values`` of :py:attr:`Dataset.coords` and :py:attr:`Dataset.data_vars` with objects returned