BUG: IntervalIndex.get_loc/get_indexer wrong return value / error

pandas/core/frame.py

@@ -4615,6 +4615,7 @@ def dropna(self, axis=0, how='any', thresh=None, subset=None,
                 else:
                     raise TypeError('must specify how or thresh')
 
+            #result = self._take(mask.to_numpy().nonzero()[0], axis=axis)
             result = self.loc(axis=axis)[mask]
 
         if inplace:

pandas/core/indexes/interval.py

@@ -766,8 +766,13 @@ def get_loc(self, key, method=None):
                 key = Interval(left, right, key.closed)
             else:
                 key = self._maybe_cast_slice_bound(key, 'left', None)
-
-            start, stop = self._find_non_overlapping_monotonic_bounds(key)
+            try:
+                start, stop = self._find_non_overlapping_monotonic_bounds(key)
+            except TypeError:
+                # get loc should raise KeyError
+                # if key is hashable but
+                # of an incorrect type
+                raise KeyError
 
             if start is None or stop is None:
                 return slice(start, stop)
@@ -819,7 +824,14 @@ def get_indexer(self, target, method=None, limit=None, tolerance=None):
             return np.arange(len(self), dtype='intp')
 
         if self.is_non_overlapping_monotonic:
-            start, stop = self._find_non_overlapping_monotonic_bounds(target)
+            try:
+                start, stop = (
+                    self._find_non_overlapping_monotonic_bounds()
+                )
+            except TypeError:
+                # This is probably wrong
+                # but not sure what I should do here
+                return np.array([-1])
 
             start_plus_one = start + 1
             if not ((start_plus_one < stop).any()):

pandas/tests/indexes/interval/test_interval.py

@@ -886,6 +886,13 @@ def test_symmetric_difference(self, closed, sort):
         result = index.symmetric_difference(other, sort=sort)
         tm.assert_index_equal(result, expected)
 
+    def test_interval_range_get_indexer_with_different_input_type(self):
+        # not sure about this one
+        index = pd.interval_range(0, 1)
+        # behaviour should be the same as Int64Index and return an
+        # array with values of -1
+        assert np.all(index.get_indexer(['gg']) == np.array([-1]))
+
     @pytest.mark.parametrize('op_name', [
         'union', 'intersection', 'difference', 'symmetric_difference'])
     @pytest.mark.parametrize("sort", [None, False])

pandas/tests/indexing/test_categorical.py

@@ -78,6 +78,12 @@ def test_getitem_scalar(self):
         result = s[cats[0]]
         assert result == expected
 
+    def test_contains_interval_range(self):
+        """Check we can use contains """
+        intervals = pd.interval_range(0.0, 1.0)
+        cats = pd.Categorical(intervals)
+        assert 'gg' not in cats
+
     def test_slicing_directly(self):
         cat = Categorical(["a", "b", "c", "d", "a", "b", "c"])
         sliced = cat[3]

pandas/tests/indexing/test_loc.py

@@ -778,3 +778,9 @@ def test_loc_setitem_empty_append_raises(self):
         msg = "cannot copy sequence with size 2 to array axis with dimension 0"
         with pytest.raises(ValueError, match=msg):
             df.loc[0:2, 'x'] = data
+
+    def test_loc_getitem_interval_index(self):
+        """ GH25087, test get_loc returns key error for interval indexes"""
+        idx = pd.interval_range(0, 1.0)
+        with pytest.raises(KeyError):
+            idx.get_loc('gg')