minor cleanups (#173)

Author: dcherian

cf_xarray/accessor.py

@@ -167,7 +167,7 @@ def _apply_single_mapper(mapper):
 
         try:
             results = mapper(obj, key)
-        except Exception as e:
+        except KeyError as e:
             if error:
                 raise e
             else:
@@ -319,7 +319,7 @@ def _get_measure_variable(
     """ tiny wrapper since xarray does not support providing str for weights."""
     varnames = apply_mapper(_get_measure, da, key, error, default)
     if len(varnames) > 1:
-        raise ValueError(f"Multiple measures found for key {key!r}: {varnames!r}.")
+        raise KeyError(f"Multiple measures found for key {key!r}: {varnames!r}.")
     return [da[varnames[0]]]
 
 
@@ -572,7 +572,7 @@ def _getitem(
 
     def check_results(names, k):
         if scalar_key and len(names) > 1:
-            raise ValueError(
+            raise KeyError(
                 f"Receive multiple variables for key {k!r}: {names}. "
                 f"Expected only one. Please pass a list [{k!r}] "
                 f"instead to get all variables matching {k!r}."
@@ -627,7 +627,7 @@ def check_results(names, k):
                     da.coords[k1] = ds.variables[k1]
                 return da
             else:
-                raise ValueError(
+                raise KeyError(
                     f"Received scalar key {key[0]!r} but multiple results: {allnames!r}. "
                     f"Please pass a list instead (['{key[0]}']) to get back a Dataset "
                     f"with {allnames!r}."

cf_xarray/datasets.py

@@ -70,7 +70,6 @@
 anc["q_detection_limit"] = xr.DataArray(
     1e-3, attrs=dict(standard_name="specific_humidity detection_minimum", units="g/g")
 )
-anc
 
 
 multiple = xr.Dataset()

cf_xarray/tests/test_accessor.py

@@ -187,7 +187,7 @@ def test_getitem_standard_name():
 
     ds = airds.copy(deep=True)
     ds["air2"] = ds.air
-    with pytest.raises(ValueError):
+    with pytest.raises(KeyError):
         ds.cf["air_temperature"]
     actual = ds.cf[["air_temperature"]]
     expected = ds[["air", "air2"]]
@@ -508,7 +508,7 @@ def test_plot_xincrease_yincrease():
     ds.lon.attrs["positive"] = "down"
     ds.lat.attrs["positive"] = "down"
 
-    f, ax = plt.subplots(1, 1)
+    _, ax = plt.subplots(1, 1)
     ds.air.isel(time=1).cf.plot(ax=ax, x="X", y="Y")
 
     for lim in [ax.get_xlim(), ax.get_ylim()]: