BUG: IntervalIndex.take without fill_value (pandas-dev#37330)

Author: jbrockmendel

doc/source/whatsnew/v1.2.0.rst

@@ -434,7 +434,7 @@ Strings
 
 Interval
 ^^^^^^^^
-
+- Bug in :meth:`IntervalIndex.take` with negative indices and ``fill_value=None`` (:issue:`37330`)
 -
 -
 

pandas/core/arrays/_mixins.py

@@ -55,12 +55,17 @@ def take(
         indices: Sequence[int],
         allow_fill: bool = False,
         fill_value: Any = None,
+        axis: int = 0,
     ) -> _T:
         if allow_fill:
             fill_value = self._validate_fill_value(fill_value)
 
         new_data = take(
-            self._ndarray, indices, allow_fill=allow_fill, fill_value=fill_value
+            self._ndarray,
+            indices,
+            allow_fill=allow_fill,
+            fill_value=fill_value,
+            axis=axis,
         )
         return self._from_backing_data(new_data)
 

pandas/core/arrays/interval.py

@@ -544,7 +544,9 @@ def __eq__(self, other):
             if is_interval_dtype(other_dtype):
                 if self.closed != other.categories.closed:
                     return np.zeros(len(self), dtype=bool)
-                other = other.categories.take(other.codes)
+                other = other.categories.take(
+                    other.codes, allow_fill=True, fill_value=other.categories._na_value
+                )
 
         # interval-like -> need same closed and matching endpoints
         if is_interval_dtype(other_dtype):

pandas/core/groupby/generic.py

@@ -714,7 +714,7 @@ def value_counts(
             # lab is a Categorical with categories an IntervalIndex
             lab = cut(Series(val), bins, include_lowest=True)
             lev = lab.cat.categories
-            lab = lev.take(lab.cat.codes)
+            lab = lev.take(lab.cat.codes, allow_fill=True, fill_value=lev._na_value)
             llab = lambda lab, inc: lab[inc]._multiindex.codes[-1]
 
         if is_interval_dtype(lab.dtype):

pandas/core/indexes/base.py

@@ -769,7 +769,7 @@ def _assert_take_fillable(
                 values, indices, allow_fill=allow_fill, fill_value=na_value
             )
         else:
-            taken = values.take(indices)
+            taken = algos.take(values, indices, allow_fill=False, fill_value=na_value)
         return taken
 
     _index_shared_docs[

pandas/core/indexes/interval.py

@@ -909,13 +909,6 @@ def insert(self, loc, item):
         result = IntervalArray.from_arrays(new_left, new_right, closed=self.closed)
         return self._shallow_copy(result)
 
-    @Appender(_index_shared_docs["take"] % _index_doc_kwargs)
-    def take(self, indices, axis=0, allow_fill=True, fill_value=None, **kwargs):
-        result = self._data.take(
-            indices, axis=axis, allow_fill=allow_fill, fill_value=fill_value, **kwargs
-        )
-        return self._shallow_copy(result)
-
     # --------------------------------------------------------------------
     # Rendering Methods
     # __repr__ associated methods are based on MultiIndex

pandas/tests/indexes/categorical/test_astype.py

@@ -25,7 +25,7 @@ def test_astype(self):
         )
 
         result = ci.astype("interval")
-        expected = ii.take([0, 1, -1])
+        expected = ii.take([0, 1, -1], allow_fill=True, fill_value=np.nan)
         tm.assert_index_equal(result, expected)
 
         result = IntervalIndex(result.values)

pandas/tests/indexes/common.py

@@ -407,6 +407,17 @@ def test_take_invalid_kwargs(self):
         with pytest.raises(ValueError, match=msg):
             idx.take(indices, mode="clip")
 
+    def test_take_minus1_without_fill(self, index):
+        # -1 does not get treated as NA unless allow_fill=True is passed
+        if len(index) == 0:
+            # Test is not applicable
+            return
+
+        result = index.take([0, 0, -1])
+
+        expected = index.take([0, 0, len(index) - 1])
+        tm.assert_index_equal(result, expected)
+
     def test_repeat(self):
         rep = 2
         i = self.create_index()