Add __contains__

Author: dcherian

cf_xarray/accessor.py

@@ -728,6 +728,12 @@ def __getattr__(self, attr):
             wrap_classes=True,
         )
 
+    def __contains__(self, item: str) -> bool:
+        """
+        Check whether item is a valid key for indexing with .cf
+        """
+        return item in self.get_valid_keys()
+
     @property
     def plot(self):
         return _CFWrappedPlotMethods(self._obj, self)

cf_xarray/tests/test_accessor.py

@@ -306,6 +306,8 @@ def test_dataset_plot(obj):
     ),
 )
 def test_getitem(obj, key, expected_key):
+    assert key in obj.cf
+
     actual = obj.cf[key]
     if isinstance(obj, xr.Dataset):
         expected_key = [expected_key]

doc/examples/introduction.ipynb

@@ -14,8 +14,8 @@
    "execution_count": null,
    "metadata": {
     "ExecuteTime": {
-     "end_time": "2020-06-30T23:25:30.534525Z",
-     "start_time": "2020-06-30T23:25:29.588662Z"
+     "end_time": "2020-07-24T20:12:00.609657Z",
+     "start_time": "2020-07-24T20:11:59.698753Z"
     }
    },
    "outputs": [],
@@ -37,8 +37,8 @@
    "execution_count": null,
    "metadata": {
     "ExecuteTime": {
-     "end_time": "2020-06-30T23:25:30.589498Z",
-     "start_time": "2020-06-30T23:25:30.536512Z"
+     "end_time": "2020-07-24T20:12:00.805176Z",
+     "start_time": "2020-07-24T20:12:00.718615Z"
     }
    },
    "outputs": [],
@@ -61,8 +61,8 @@
    "execution_count": null,
    "metadata": {
     "ExecuteTime": {
-     "end_time": "2020-06-30T23:25:30.651949Z",
-     "start_time": "2020-06-30T23:25:30.591221Z"
+     "end_time": "2020-07-24T20:12:02.140074Z",
+     "start_time": "2020-07-24T20:12:02.050083Z"
     }
    },
    "outputs": [],
@@ -434,15 +434,36 @@
    "execution_count": null,
    "metadata": {
     "ExecuteTime": {
-     "end_time": "2020-06-30T23:25:31.205009Z",
-     "start_time": "2020-06-30T23:25:31.186385Z"
+     "end_time": "2020-07-24T20:12:06.956464Z",
+     "start_time": "2020-07-24T20:12:06.908943Z"
     }
    },
    "outputs": [],
    "source": [
     "pop.cf.get_valid_keys()"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "You can test for presence of these keys\n"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "ExecuteTime": {
+     "end_time": "2020-07-24T20:12:36.699151Z",
+     "start_time": "2020-07-24T20:12:36.664209Z"
+    }
+   },
+   "outputs": [],
+   "source": [
+    "\"sea_water_x_velocity\" in pop.cf"
+   ]
+  },
   {
    "cell_type": "markdown",
    "metadata": {},