Use DataArray.cf.is_flag_variable

Author: dcherian

cf_xarray/accessor.py

@@ -886,19 +886,8 @@ def __getattr__(self, attr):
         )
 
 
-def _is_cf_flag_variable(da):
-    if (
-        isinstance(da, xr.DataArray)
-        and "flag_meanings" in da.attrs
-        and "flag_values" in da.attrs
-    ):
-        return True
-    else:
-        return False
-
-
 def create_flag_dict(da):
-    if not _is_cf_flag_variable(da):
+    if not da.cf.is_flag_variable:
         raise ValueError(
             "Comparisons are only supported for DataArrays that represent CF flag variables."
             ".attrs must contain 'flag_values' and 'flag_meanings'"
@@ -1256,7 +1245,7 @@ def make_text_section(subtitle, attr, valid_values, default_keys=None):
 
             return "\n".join(rows) + "\n"
 
-        if _is_cf_flag_variable(self._obj):
+        if self._obj.is_flag_variable(self._obj):
             flag_dict = create_flag_dict(self._obj)
             text = f"CF Flag variable with mapping:\n\t{flag_dict!r}\n\n"
         else:
@@ -2188,4 +2177,18 @@ def __getitem__(self, key: Union[str, List[str]]) -> DataArray:
 
         return _getitem(self, key)
 
-    pass
+    @property
+    def is_flag_variable(self):
+        """
+        Returns True if the DataArray satisfies CF conventions for flag variables.
+
+        Flag masks are not supported yet.
+        """
+        if (
+            isinstance(self._obj, xr.DataArray)
+            and "flag_meanings" in self._obj.attrs
+            and "flag_values" in self._obj.attrs
+        ):
+            return True
+        else:
+            return False

doc/api.rst

@@ -31,6 +31,7 @@ Attributes
     DataArray.cf.cell_measures
     DataArray.cf.coordinates
     DataArray.cf.formula_terms
+    DataArray.cf.is_flag_variable
     DataArray.cf.standard_names
     DataArray.cf.plot