From 516590b03f3f84df689338131a7caf5af651fdc2 Mon Sep 17 00:00:00 2001
From: Brock <jbrockmendel@gmail.com>
Date: Tue, 17 Nov 2020 13:21:55 -0800
Subject: [PATCH 1/2] REF: de-duplicate pointwise get_indexer for IntervalIndex

---
 pandas/core/indexes/base.py     |  2 +-
 pandas/core/indexes/interval.py | 52 ++++++++++++++++++---------------
 2 files changed, 29 insertions(+), 25 deletions(-)

diff --git a/pandas/core/indexes/base.py b/pandas/core/indexes/base.py
index 9ea0ff323a33d..5c90269106d40 100644
--- a/pandas/core/indexes/base.py
+++ b/pandas/core/indexes/base.py
@@ -3122,7 +3122,7 @@ def get_indexer(
                 target, method=method, limit=limit, tolerance=tolerance
             )
 
-        if not self.is_unique:
+        if not self._index_as_unique:
             raise InvalidIndexError(
                 "Reindexing only valid with uniquely valued Index objects"
             )
diff --git a/pandas/core/indexes/interval.py b/pandas/core/indexes/interval.py
index 267d1330faceb..633f4e3127bf6 100644
--- a/pandas/core/indexes/interval.py
+++ b/pandas/core/indexes/interval.py
@@ -704,7 +704,7 @@ def get_indexer(
 
         self._check_indexing_method(method)
 
-        if self.is_overlapping:
+        if not self._index_as_unique:
             raise InvalidIndexError(
                 "cannot handle overlapping indices; "
                 "use IntervalIndex.get_indexer_non_unique"
@@ -741,17 +741,7 @@ def get_indexer(
             indexer = self._engine.get_indexer(target_as_index.values)
         else:
             # heterogeneous scalar index: defer elementwise to get_loc
-            # (non-overlapping so get_loc guarantees scalar of KeyError)
-            indexer = []
-            for key in target_as_index:
-                try:
-                    loc = self.get_loc(key)
-                except KeyError:
-                    loc = -1
-                except InvalidIndexError as err:
-                    # i.e. non-scalar key
-                    raise TypeError(key) from err
-                indexer.append(loc)
+            return self._get_indexer_pointwise(target_as_index)[0]
 
         return ensure_platform_int(indexer)
 
@@ -777,18 +767,8 @@ def get_indexer_non_unique(
             target_as_index, IntervalIndex
         ):
             # target_as_index might contain intervals: defer elementwise to get_loc
-            indexer, missing = [], []
-            for i, key in enumerate(target_as_index):
-                try:
-                    locs = self.get_loc(key)
-                    if isinstance(locs, slice):
-                        locs = np.arange(locs.start, locs.stop, locs.step, dtype="intp")
-                    locs = np.array(locs, ndmin=1)
-                except KeyError:
-                    missing.append(i)
-                    locs = np.array([-1])
-                indexer.append(locs)
-            indexer = np.concatenate(indexer)
+            return self._get_indexer_pointwise(target_as_index)
+
         else:
             target_as_index = self._maybe_convert_i8(target_as_index)
             indexer, missing = self._engine.get_indexer_non_unique(
@@ -797,6 +777,30 @@ def get_indexer_non_unique(
 
         return ensure_platform_int(indexer), ensure_platform_int(missing)
 
+    def _get_indexer_pointwise(self, target: Index):
+        """
+        pointwise implementation for get_indexer and get_indexer_non_unique.
+        """
+        indexer, missing = [], []
+        for i, key in enumerate(target):
+            try:
+                locs = self.get_loc(key)
+                if isinstance(locs, slice):
+                    # Only needed for get_indexer_non_unique
+                    locs = np.arange(locs.start, locs.stop, locs.step, dtype="intp")
+                locs = np.array(locs, ndmin=1)
+            except KeyError:
+                missing.append(i)
+                locs = np.array([-1])
+            except InvalidIndexError as err:
+                # i.e. non-scalar key
+                raise TypeError(key) from err
+
+            indexer.append(locs)
+
+        indexer = np.concatenate(indexer)
+        return ensure_platform_int(indexer), ensure_platform_int(missing)
+
     @property
     def _index_as_unique(self):
         return not self.is_overlapping

From 14dd579e5242ccda63b1f062ebbce76b490eaf0f Mon Sep 17 00:00:00 2001
From: Brock <jbrockmendel@gmail.com>
Date: Tue, 17 Nov 2020 18:51:30 -0800
Subject: [PATCH 2/2] annotate

---
 pandas/core/indexes/base.py     | 2 +-
 pandas/core/indexes/interval.py | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/pandas/core/indexes/base.py b/pandas/core/indexes/base.py
index db85619663d9d..1b3e4864843f3 100644
--- a/pandas/core/indexes/base.py
+++ b/pandas/core/indexes/base.py
@@ -3124,7 +3124,7 @@ def get_indexer(
                 target, method=method, limit=limit, tolerance=tolerance
             )
 
-        if not self._index_as_unique:
+        if not self.is_unique:
             raise InvalidIndexError(
                 "Reindexing only valid with uniquely valued Index objects"
             )
diff --git a/pandas/core/indexes/interval.py b/pandas/core/indexes/interval.py
index 2d9f190937659..b0f8be986fe5d 100644
--- a/pandas/core/indexes/interval.py
+++ b/pandas/core/indexes/interval.py
@@ -698,7 +698,7 @@ def get_indexer(
 
         self._check_indexing_method(method)
 
-        if not self._index_as_unique:
+        if self.is_overlapping:
             raise InvalidIndexError(
                 "cannot handle overlapping indices; "
                 "use IntervalIndex.get_indexer_non_unique"
@@ -766,7 +766,7 @@ def get_indexer_non_unique(
 
         return ensure_platform_int(indexer), ensure_platform_int(missing)
 
-    def _get_indexer_pointwise(self, target: Index):
+    def _get_indexer_pointwise(self, target: Index) -> Tuple[np.ndarray, np.ndarray]:
         """
         pointwise implementation for get_indexer and get_indexer_non_unique.
         """