From 2aca38998c11a6db707b82a81f4252f1bb6a8125 Mon Sep 17 00:00:00 2001
From: Samuel <samuelsinayoko@bmlltech.com>
Date: Sat, 2 Feb 2019 12:22:19 +0000
Subject: [PATCH 01/24] Revert earlier change and use to_numpy

Revert #24048 change that caused bug.
---
 pandas/core/frame.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/core/frame.py b/pandas/core/frame.py
index ade05ab27093e..1730c2cc78e2a 100644
--- a/pandas/core/frame.py
+++ b/pandas/core/frame.py
@@ -4615,7 +4615,7 @@ def dropna(self, axis=0, how='any', thresh=None, subset=None,
                 else:
                     raise TypeError('must specify how or thresh')
 
-            result = self.loc(axis=axis)[mask]
+            result = self._take(mask.nonzero()[0], axis=axis)
 
         if inplace:
             self._update_inplace(result)

From 2d12d2fbc4c906ce7c22121a4b18a649725cfab1 Mon Sep 17 00:00:00 2001
From: Samuel <samuelsinayoko@bmlltech.com>
Date: Sat, 2 Feb 2019 12:25:47 +0000
Subject: [PATCH 02/24] Remove warning by using to_numpy

---
 pandas/core/frame.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/core/frame.py b/pandas/core/frame.py
index 1730c2cc78e2a..daa6a6683e6b9 100644
--- a/pandas/core/frame.py
+++ b/pandas/core/frame.py
@@ -4615,7 +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.nonzero()[0], axis=axis)
+            result = self._take(mask.to_numpy()nonzero()[0], axis=axis)
 
         if inplace:
             self._update_inplace(result)

From f3571011e1d68a9b0c4421b3eada050ce29cba65 Mon Sep 17 00:00:00 2001
From: Samuel <samuelsinayoko@bmlltech.com>
Date: Sat, 2 Feb 2019 12:26:17 +0000
Subject: [PATCH 03/24] Make warning go away

---
 pandas/core/frame.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/core/frame.py b/pandas/core/frame.py
index daa6a6683e6b9..4a930aab7fd93 100644
--- a/pandas/core/frame.py
+++ b/pandas/core/frame.py
@@ -4615,7 +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._take(mask.to_numpy().nonzero()[0], axis=axis)
 
         if inplace:
             self._update_inplace(result)

From 7cc4c372c300ce168ccb2937453b9caa88fe3a2d Mon Sep 17 00:00:00 2001
From: Samuel <samuelsinayoko@bmlltech.com>
Date: Sat, 2 Feb 2019 15:56:02 +0000
Subject: [PATCH 04/24] revert initial bugfix

Write tests first
---
 pandas/core/frame.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/pandas/core/frame.py b/pandas/core/frame.py
index 4a930aab7fd93..9d3922edd9d6e 100644
--- a/pandas/core/frame.py
+++ b/pandas/core/frame.py
@@ -4615,7 +4615,8 @@ 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._take(mask.to_numpy().nonzero()[0], axis=axis)
+            result = self.loc(axis=axis)[mask]
 
         if inplace:
             self._update_inplace(result)

From 8ec653a01a477fb9b9e72668ba44ca21e608e3dc Mon Sep 17 00:00:00 2001
From: Samuel <samuelsinayoko@bmlltech.com>
Date: Sat, 2 Feb 2019 15:56:19 +0000
Subject: [PATCH 05/24] Add test for contains in interval index categorical

When tested with a variable that has the wrong dtype, this raises an
exception instead of False
---
 pandas/tests/indexing/test_categorical.py | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/pandas/tests/indexing/test_categorical.py b/pandas/tests/indexing/test_categorical.py
index 317aac1766cf8..cdfb48fafbdb6 100644
--- a/pandas/tests/indexing/test_categorical.py
+++ b/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]

From 878802e7b7c8930711af5729ddd6479711d729c6 Mon Sep 17 00:00:00 2001
From: Samuel <samuelsinayoko@bmlltech.com>
Date: Sat, 2 Feb 2019 16:07:35 +0000
Subject: [PATCH 06/24] Check get_loc on interval index raises KeyError

When supplied a variable with the wrong type get_loc should raise a
KeyError (not type error). Otherwise things like checking if a variable
is in an index will fail.
---
 pandas/tests/indexing/test_loc.py | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/pandas/tests/indexing/test_loc.py b/pandas/tests/indexing/test_loc.py
index 3bf4a6bee4af9..6e7906eede639 100644
--- a/pandas/tests/indexing/test_loc.py
+++ b/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')

From 4dabe0e45ad5124e459a8d0c04e02fbcfcc6bcfa Mon Sep 17 00:00:00 2001
From: Samuel <samuelsinayoko@bmlltech.com>
Date: Sat, 2 Feb 2019 16:18:00 +0000
Subject: [PATCH 07/24] Add test for get_indexer

---
 pandas/tests/indexes/interval/test_interval.py | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/pandas/tests/indexes/interval/test_interval.py b/pandas/tests/indexes/interval/test_interval.py
index f1fd06c9cab6e..60d3a473138cc 100644
--- a/pandas/tests/indexes/interval/test_interval.py
+++ b/pandas/tests/indexes/interval/test_interval.py
@@ -886,6 +886,12 @@ def test_symmetric_difference(self, closed, sort):
         result = index.symmetric_difference(other, sort=sort)
         tm.assert_index_equal(result, expected)
 
+    def test_get_indexer_errors(self):
+        # not sure about this one
+        index = pd.interval_range(0, 1)
+        with pytest.raises(KeyError):
+            index.get_indexer(['gg'])
+
     @pytest.mark.parametrize('op_name', [
         'union', 'intersection', 'difference', 'symmetric_difference'])
     @pytest.mark.parametrize("sort", [None, False])

From 564d88dadca3113a3e6896d414c7687d81c76874 Mon Sep 17 00:00:00 2001
From: Samuel <samuelsinayoko@bmlltech.com>
Date: Sat, 2 Feb 2019 16:20:34 +0000
Subject: [PATCH 08/24] Add a test for get_indexer with different type

---
 pandas/tests/indexes/interval/test_interval.py | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/pandas/tests/indexes/interval/test_interval.py b/pandas/tests/indexes/interval/test_interval.py
index 60d3a473138cc..8e680d92da670 100644
--- a/pandas/tests/indexes/interval/test_interval.py
+++ b/pandas/tests/indexes/interval/test_interval.py
@@ -886,11 +886,12 @@ def test_symmetric_difference(self, closed, sort):
         result = index.symmetric_difference(other, sort=sort)
         tm.assert_index_equal(result, expected)
 
-    def test_get_indexer_errors(self):
+    def test_interval_range_get_indexer_with_different_input_type(self):
         # not sure about this one
         index = pd.interval_range(0, 1)
-        with pytest.raises(KeyError):
-            index.get_indexer(['gg'])
+        # 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'])

From f4c43e30d8d0ad65ead1078c82041ed75a0ac9ed Mon Sep 17 00:00:00 2001
From: Samuel <samuelsinayoko@bmlltech.com>
Date: Sat, 2 Feb 2019 16:30:50 +0000
Subject: [PATCH 09/24] Make first two tests pass

---
 pandas/core/indexes/interval.py | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/pandas/core/indexes/interval.py b/pandas/core/indexes/interval.py
index 2c63fe33c57fe..507f183c0d73a 100644
--- a/pandas/core/indexes/interval.py
+++ b/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)

From a09a07e4dabe91a8cfe46bec40414a2ddc4225a3 Mon Sep 17 00:00:00 2001
From: Samuel <samuelsinayoko@bmlltech.com>
Date: Sat, 2 Feb 2019 16:30:58 +0000
Subject: [PATCH 10/24] Make third test pass

This is enough for making the test pass but it's not the right implementation
---
 pandas/core/indexes/interval.py | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/pandas/core/indexes/interval.py b/pandas/core/indexes/interval.py
index 507f183c0d73a..b06358910724c 100644
--- a/pandas/core/indexes/interval.py
+++ b/pandas/core/indexes/interval.py
@@ -824,7 +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()):

From 6c887e6b03e5a632dcbf50fd69a149a13773243e Mon Sep 17 00:00:00 2001
From: Samuel <samuelsinayoko@bmlltech.com>
Date: Sun, 3 Feb 2019 18:46:00 +0000
Subject: [PATCH 11/24] remove commented out code

---
 pandas/core/frame.py | 1 -
 1 file changed, 1 deletion(-)

diff --git a/pandas/core/frame.py b/pandas/core/frame.py
index 9d3922edd9d6e..ade05ab27093e 100644
--- a/pandas/core/frame.py
+++ b/pandas/core/frame.py
@@ -4615,7 +4615,6 @@ 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:

From 0a143f261e41fc6fb2c7dd69fb7af745b543746e Mon Sep 17 00:00:00 2001
From: Samuel <samuelsinayoko@bmlltech.com>
Date: Sun, 3 Feb 2019 18:49:12 +0000
Subject: [PATCH 12/24] Improve error message

---
 pandas/core/indexes/interval.py | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/pandas/core/indexes/interval.py b/pandas/core/indexes/interval.py
index b06358910724c..1efbfb204c6d9 100644
--- a/pandas/core/indexes/interval.py
+++ b/pandas/core/indexes/interval.py
@@ -769,10 +769,8 @@ def get_loc(self, key, method=None):
             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
+                # get_loc should raise KeyError
+                raise KeyError('key is hashable but of incorrect type')
 
             if start is None or stop is None:
                 return slice(start, stop)

From 0730cd613f87cf98b301efac335188e3d7f93d02 Mon Sep 17 00:00:00 2001
From: Samuel <samuelsinayoko@bmlltech.com>
Date: Sun, 3 Feb 2019 20:50:53 +0000
Subject: [PATCH 13/24] Rename, move and parametrize indexer test

Include some non-monotonic/overlapping IntervalIndex.
This triggers another bug, due to the fact that self.get_loc(i)
is called on an unexpected key.
---
 pandas/core/indexes/interval.py                | 16 +++++++++++++---
 pandas/tests/indexes/interval/test_interval.py | 14 +++++++-------
 2 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/pandas/core/indexes/interval.py b/pandas/core/indexes/interval.py
index 1efbfb204c6d9..d6f026667a643 100644
--- a/pandas/core/indexes/interval.py
+++ b/pandas/core/indexes/interval.py
@@ -788,7 +788,10 @@ def get_loc(self, key, method=None):
                 left, right = _get_interval_closed_bounds(key)
                 return self._engine.get_loc_interval(left, right)
             else:
-                return self._engine.get_loc(key)
+                try:
+                    return self._engine.get_loc(key)
+                except TypeError:
+                    raise KeyError('No engine for key {!r}'.format(key))
 
     def get_value(self, series, key):
         if com.is_bool_indexer(key):
@@ -829,7 +832,8 @@ def get_indexer(self, target, method=None, limit=None, tolerance=None):
             except TypeError:
                 # This is probably wrong
                 # but not sure what I should do here
-                return np.array([-1])
+                #return np.array([-1])
+                return np.repeat(np.int(-1), len(target))
 
             start_plus_one = start + 1
             if not ((start_plus_one < stop).any()):
@@ -844,7 +848,13 @@ def get_indexer(self, target, method=None, limit=None, tolerance=None):
 
         # non IntervalIndex
         else:
-            indexer = np.concatenate([self.get_loc(i) for i in target])
+            vals = []
+            for i in target:
+                try:
+                    vals.append(self.get_loc(i))
+                except KeyError:
+                    vals.append(np.array([-1]))
+                indexer = np.concatenate(vals)
 
         return ensure_platform_int(indexer)
 
diff --git a/pandas/tests/indexes/interval/test_interval.py b/pandas/tests/indexes/interval/test_interval.py
index 8e680d92da670..0ae519e5727ab 100644
--- a/pandas/tests/indexes/interval/test_interval.py
+++ b/pandas/tests/indexes/interval/test_interval.py
@@ -616,6 +616,13 @@ def test_get_indexer_length_one(self, item, closed):
         expected = np.array([0] * len(item), dtype='intp')
         tm.assert_numpy_array_equal(result, expected)
 
+    @pytest.mark.parametrize('index', [
+        pd.interval_range(0, 1),
+        pd.IntervalIndex.from_tuples([(1, 3), (2, 4), (0, 2)])
+    ])
+    def test_get_indexer_errors(self, index):
+        assert np.all(index.get_indexer(['gg']) == np.array([-1]))
+
     # Make consistent with test_interval_new.py (see #16316, #16386)
     @pytest.mark.parametrize('arrays', [
         (date_range('20180101', periods=4), date_range('20180103', periods=4)),
@@ -886,13 +893,6 @@ 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])

From 246eb57e00f98b3fb199b9b0a5f1753d2ede420a Mon Sep 17 00:00:00 2001
From: Samuel <samuelsinayoko@bmlltech.com>
Date: Sun, 3 Feb 2019 20:58:46 +0000
Subject: [PATCH 14/24] Use numpy_array_equal in indexer test

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

diff --git a/pandas/core/indexes/interval.py b/pandas/core/indexes/interval.py
index d6f026667a643..721ef0c7f06f5 100644
--- a/pandas/core/indexes/interval.py
+++ b/pandas/core/indexes/interval.py
@@ -830,9 +830,6 @@ def get_indexer(self, target, method=None, limit=None, tolerance=None):
                     self._find_non_overlapping_monotonic_bounds()
                 )
             except TypeError:
-                # This is probably wrong
-                # but not sure what I should do here
-                #return np.array([-1])
                 return np.repeat(np.int(-1), len(target))
 
             start_plus_one = start + 1
diff --git a/pandas/tests/indexes/interval/test_interval.py b/pandas/tests/indexes/interval/test_interval.py
index 0ae519e5727ab..e8855f4dd6a73 100644
--- a/pandas/tests/indexes/interval/test_interval.py
+++ b/pandas/tests/indexes/interval/test_interval.py
@@ -621,7 +621,8 @@ def test_get_indexer_length_one(self, item, closed):
         pd.IntervalIndex.from_tuples([(1, 3), (2, 4), (0, 2)])
     ])
     def test_get_indexer_errors(self, index):
-        assert np.all(index.get_indexer(['gg']) == np.array([-1]))
+        expected = np.array([-1], dtype='intp')
+        assert tm.assert_numpy_array_equal(index.get_indexer(['gg']), expected)
 
     # Make consistent with test_interval_new.py (see #16316, #16386)
     @pytest.mark.parametrize('arrays', [

From 93f75ea4a36a9fabc610af7f35634f82a3e3e6e9 Mon Sep 17 00:00:00 2001
From: Samuel <samuelsinayoko@bmlltech.com>
Date: Mon, 4 Feb 2019 06:51:40 +0000
Subject: [PATCH 15/24] Refactor interval index get_loc test

Move the test from indexing/test_loc to index/interval/test_interval.
---
 pandas/tests/indexes/interval/test_interval.py | 8 ++++++++
 pandas/tests/indexing/test_loc.py              | 6 ------
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/pandas/tests/indexes/interval/test_interval.py b/pandas/tests/indexes/interval/test_interval.py
index e8855f4dd6a73..fcbb04d2b71a4 100644
--- a/pandas/tests/indexes/interval/test_interval.py
+++ b/pandas/tests/indexes/interval/test_interval.py
@@ -435,6 +435,14 @@ def test_get_loc_value(self):
         idx = IntervalIndex.from_arrays([0, 2], [1, 3])
         pytest.raises(KeyError, idx.get_loc, 1.5)
 
+        # GH25087, test get_loc returns key error for interval indexes
+        msg = 'key is hashable but of incorrect type'
+        with pytest.raises(KeyError, match=msg):
+            idx.get_loc('a')
+        idx = pd.interval_range(0, 1.0)
+        with pytest.raises(KeyError, match=msg):
+            idx.get_loc('a')
+
     # To be removed, replaced by test_interval_new.py (see #16316, #16386)
     def slice_locs_cases(self, breaks):
         # TODO: same tests for more index types
diff --git a/pandas/tests/indexing/test_loc.py b/pandas/tests/indexing/test_loc.py
index 6e7906eede639..3bf4a6bee4af9 100644
--- a/pandas/tests/indexing/test_loc.py
+++ b/pandas/tests/indexing/test_loc.py
@@ -778,9 +778,3 @@ 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')

From 268db81d6ccfbb82201e071b8b5ebdc5a3abf647 Mon Sep 17 00:00:00 2001
From: Samuel <samuelsinayoko@bmlltech.com>
Date: Mon, 4 Feb 2019 07:31:58 +0000
Subject: [PATCH 16/24] Fix bug introduced in earlier commit

target was missing from call to _find_non_overlapping_monotonic_bounds
---
 pandas/core/indexes/interval.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/core/indexes/interval.py b/pandas/core/indexes/interval.py
index 721ef0c7f06f5..f3c6dbc931a5d 100644
--- a/pandas/core/indexes/interval.py
+++ b/pandas/core/indexes/interval.py
@@ -827,7 +827,7 @@ def get_indexer(self, target, method=None, limit=None, tolerance=None):
         if self.is_non_overlapping_monotonic:
             try:
                 start, stop = (
-                    self._find_non_overlapping_monotonic_bounds()
+                    self._find_non_overlapping_monotonic_bounds(target)
                 )
             except TypeError:
                 return np.repeat(np.int(-1), len(target))

From a5aa1e8c336dcf605392454309c7ca43c3b09b98 Mon Sep 17 00:00:00 2001
From: Sam Sinayoko <samuelsinayoko@bmlltech.com>
Date: Wed, 6 Feb 2019 07:51:59 +0000
Subject: [PATCH 17/24] Add reminder comment to use raise from for python 3

---
 pandas/core/indexes/interval.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/pandas/core/indexes/interval.py b/pandas/core/indexes/interval.py
index f3c6dbc931a5d..478566f6589b6 100644
--- a/pandas/core/indexes/interval.py
+++ b/pandas/core/indexes/interval.py
@@ -770,6 +770,7 @@ def get_loc(self, key, method=None):
                 start, stop = self._find_non_overlapping_monotonic_bounds(key)
             except TypeError:
                 # get_loc should raise KeyError
+                # TODO(py3): use raise from.
                 raise KeyError('key is hashable but of incorrect type')
 
             if start is None or stop is None:

From d480872281d53e8c7ae665379bee5c69bc19e901 Mon Sep 17 00:00:00 2001
From: Sam Sinayoko <samuelsinayoko@bmlltech.com>
Date: Wed, 6 Feb 2019 07:53:57 +0000
Subject: [PATCH 18/24] Include key in error message.

---
 pandas/core/indexes/interval.py                | 7 +++++--
 pandas/tests/indexes/interval/test_interval.py | 5 +++--
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/pandas/core/indexes/interval.py b/pandas/core/indexes/interval.py
index 478566f6589b6..c2f4b9adbe2f3 100644
--- a/pandas/core/indexes/interval.py
+++ b/pandas/core/indexes/interval.py
@@ -771,7 +771,8 @@ def get_loc(self, key, method=None):
             except TypeError:
                 # get_loc should raise KeyError
                 # TODO(py3): use raise from.
-                raise KeyError('key is hashable but of incorrect type')
+                raise KeyError('Key {!r} is hashable but of incorrect type.'
+                               .format(key))
 
             if start is None or stop is None:
                 return slice(start, stop)
@@ -792,7 +793,9 @@ def get_loc(self, key, method=None):
                 try:
                     return self._engine.get_loc(key)
                 except TypeError:
-                    raise KeyError('No engine for key {!r}'.format(key))
+                    msg = ('Key {!r} not found (does match index type {}).'
+                           .format(key, self.dtype))
+                    raise KeyError(msg)
 
     def get_value(self, series, key):
         if com.is_bool_indexer(key):
diff --git a/pandas/tests/indexes/interval/test_interval.py b/pandas/tests/indexes/interval/test_interval.py
index fcbb04d2b71a4..7e4c453f67866 100644
--- a/pandas/tests/indexes/interval/test_interval.py
+++ b/pandas/tests/indexes/interval/test_interval.py
@@ -436,9 +436,10 @@ def test_get_loc_value(self):
         pytest.raises(KeyError, idx.get_loc, 1.5)
 
         # GH25087, test get_loc returns key error for interval indexes
-        msg = 'key is hashable but of incorrect type'
+        key = 'a'
+        msg = 'Key {!r} is hashable but of incorrect type'.format(key)
         with pytest.raises(KeyError, match=msg):
-            idx.get_loc('a')
+            idx.get_loc(key)
         idx = pd.interval_range(0, 1.0)
         with pytest.raises(KeyError, match=msg):
             idx.get_loc('a')

From 6ed1080df9240643d4479981a9e0a95423aad484 Mon Sep 17 00:00:00 2001
From: Sam Sinayoko <samuelsinayoko@bmlltech.com>
Date: Wed, 6 Feb 2019 08:46:43 +0000
Subject: [PATCH 19/24] Add larger interval range to test

---
 pandas/tests/indexes/interval/test_interval.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/pandas/tests/indexes/interval/test_interval.py b/pandas/tests/indexes/interval/test_interval.py
index 7e4c453f67866..bd483d33960de 100644
--- a/pandas/tests/indexes/interval/test_interval.py
+++ b/pandas/tests/indexes/interval/test_interval.py
@@ -627,6 +627,7 @@ def test_get_indexer_length_one(self, item, closed):
 
     @pytest.mark.parametrize('index', [
         pd.interval_range(0, 1),
+        pd.interval_range(0, 3),
         pd.IntervalIndex.from_tuples([(1, 3), (2, 4), (0, 2)])
     ])
     def test_get_indexer_errors(self, index):

From 120e2bc32ce32b7239c2a7e5b8d34295d704bab9 Mon Sep 17 00:00:00 2001
From: Sam Sinayoko <samuelsinayoko@bmlltech.com>
Date: Wed, 6 Feb 2019 08:51:53 +0000
Subject: [PATCH 20/24] get_loc should raise KeyError if the supplied key has
 the wrong type

---
 pandas/core/indexes/interval.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/core/indexes/interval.py b/pandas/core/indexes/interval.py
index c2f4b9adbe2f3..b4509c80ed8bf 100644
--- a/pandas/core/indexes/interval.py
+++ b/pandas/core/indexes/interval.py
@@ -809,7 +809,7 @@ def get_value(self, series, key):
 
             try:
                 loc = self.get_loc(key)
-            except TypeError:
+            except KeyError:
                 # we didn't find exact intervals or are non-unique
                 msg = "unable to slice with this key: {key}".format(key=key)
                 raise ValueError(msg)

From 2c4827236983c4c4755661bede38daa40d3f2067 Mon Sep 17 00:00:00 2001
From: Samuel <samuelsinayoko@bmlltech.com>
Date: Sun, 10 Feb 2019 17:41:18 +0000
Subject: [PATCH 21/24] Only return -1 in get_indexer for incorrect values

Instead of returning [-1, -1, -1] when the middle value is incorrect
type, return [a, -1, b].
---
 pandas/core/indexes/interval.py                | 13 ++++++-------
 pandas/tests/indexes/interval/test_interval.py |  8 ++++++++
 2 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/pandas/core/indexes/interval.py b/pandas/core/indexes/interval.py
index b4509c80ed8bf..436172f1f53fe 100644
--- a/pandas/core/indexes/interval.py
+++ b/pandas/core/indexes/interval.py
@@ -833,12 +833,11 @@ def get_indexer(self, target, method=None, limit=None, tolerance=None):
                 start, stop = (
                     self._find_non_overlapping_monotonic_bounds(target)
                 )
+                start_plus_one = start + 1
+                if not ((start_plus_one < stop).any()):
+                    return np.where(start_plus_one == stop, start, -1)
             except TypeError:
-                return np.repeat(np.int(-1), len(target))
-
-            start_plus_one = start + 1
-            if not ((start_plus_one < stop).any()):
-                return np.where(start_plus_one == stop, start, -1)
+                pass
 
         if not self.is_unique:
             raise ValueError("cannot handle non-unique indices")
@@ -854,8 +853,8 @@ def get_indexer(self, target, method=None, limit=None, tolerance=None):
                 try:
                     vals.append(self.get_loc(i))
                 except KeyError:
-                    vals.append(np.array([-1]))
-                indexer = np.concatenate(vals)
+                    vals.append(-1)
+            indexer = np.array(vals)
 
         return ensure_platform_int(indexer)
 
diff --git a/pandas/tests/indexes/interval/test_interval.py b/pandas/tests/indexes/interval/test_interval.py
index bd483d33960de..32b0dd708776d 100644
--- a/pandas/tests/indexes/interval/test_interval.py
+++ b/pandas/tests/indexes/interval/test_interval.py
@@ -591,6 +591,14 @@ def test_get_indexer(self):
         expected = np.array([-1, 1], dtype='intp')
         tm.assert_numpy_array_equal(actual, expected)
 
+        actual = self.index.get_indexer(['a', 1])
+        expected = np.array([-1, 0], dtype='intp')
+        tm.assert_numpy_array_equal(actual, expected)
+
+        actual = self.index.get_indexer(['a', 1, 'b'])
+        expected = np.array([-1, 0, -1], dtype='intp')
+        tm.assert_numpy_array_equal(actual, expected)
+
     # To be removed, replaced by test_interval_new.py (see #16316, #16386)
     def test_get_indexer_subintervals(self):
 

From 02127ffc4df205ca8076119a2537f8372f0a1eca Mon Sep 17 00:00:00 2001
From: Samuel <samuelsinayoko@bmlltech.com>
Date: Sun, 10 Feb 2019 17:57:01 +0000
Subject: [PATCH 22/24] Better tests for get_indexer_errors

Add mix of invalid and valid values
---
 .../tests/indexes/interval/test_interval.py   | 21 +++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/pandas/tests/indexes/interval/test_interval.py b/pandas/tests/indexes/interval/test_interval.py
index 32b0dd708776d..3759a2ec0ba6d 100644
--- a/pandas/tests/indexes/interval/test_interval.py
+++ b/pandas/tests/indexes/interval/test_interval.py
@@ -633,14 +633,23 @@ def test_get_indexer_length_one(self, item, closed):
         expected = np.array([0] * len(item), dtype='intp')
         tm.assert_numpy_array_equal(result, expected)
 
-    @pytest.mark.parametrize('index', [
-        pd.interval_range(0, 1),
-        pd.interval_range(0, 3),
-        pd.IntervalIndex.from_tuples([(1, 3), (2, 4), (0, 2)])
+    @pytest.mark.parametrize('index,value,expected_index', [
+        (pd.interval_range(0, 1), 0.5, 0),
+        (pd.interval_range(0, 3), 0.5, 0),
+        (pd.IntervalIndex.from_tuples([(1, 3), (2, 4), (0, 2)]), 0.5, 2)
     ])
-    def test_get_indexer_errors(self, index):
+    def test_get_indexer_errors(self, index, value, expected_index):
+        actual = index.get_indexer(['a'])
         expected = np.array([-1], dtype='intp')
-        assert tm.assert_numpy_array_equal(index.get_indexer(['gg']), expected)
+        assert tm.assert_numpy_array_equal(actual, expected)
+
+        actual = index.get_indexer(['a', 'b'])
+        expected = np.array([-1, -1], dtype='intp')
+        assert tm.assert_numpy_array_equal(actual, expected)
+
+        actual = index.get_indexer(['a', value, 'b'])
+        expected = np.array([-1, expected_index, -1], dtype='intp')
+        assert tm.assert_numpy_array_equal(actual, expected)
 
     # Make consistent with test_interval_new.py (see #16316, #16386)
     @pytest.mark.parametrize('arrays', [

From ad13d9e121cb90f49890d54f7c58f18b6f9ea10c Mon Sep 17 00:00:00 2001
From: Sam Sinayoko <samuelsinayoko@bmlltech.com>
Date: Mon, 11 Feb 2019 08:58:58 +0000
Subject: [PATCH 23/24] Fix broken test in test_interval

Fixes test_with_overlaps test
---
 pandas/core/indexes/interval.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/core/indexes/interval.py b/pandas/core/indexes/interval.py
index 436172f1f53fe..2dcf8a12cfb74 100644
--- a/pandas/core/indexes/interval.py
+++ b/pandas/core/indexes/interval.py
@@ -854,7 +854,7 @@ def get_indexer(self, target, method=None, limit=None, tolerance=None):
                     vals.append(self.get_loc(i))
                 except KeyError:
                     vals.append(-1)
-            indexer = np.array(vals)
+            indexer = np.array(vals).flatten()
 
         return ensure_platform_int(indexer)
 

From 0ff356cd374752fbb6b309a3fce515c21c3e747b Mon Sep 17 00:00:00 2001
From: Samuel <samuelsinayoko@bmlltech.com>
Date: Sat, 16 Feb 2019 16:29:02 +0000
Subject: [PATCH 24/24] Fix broken tests in test_concat

interval.get_indexer() should still raise a TypeError in cases
where the types are unorderable. This is needed for DataFrame.append
for example, which was breaking tests in test_concat.
---
 pandas/core/indexes/interval.py | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/pandas/core/indexes/interval.py b/pandas/core/indexes/interval.py
index 2dcf8a12cfb74..c2930d985fb53 100644
--- a/pandas/core/indexes/interval.py
+++ b/pandas/core/indexes/interval.py
@@ -836,8 +836,14 @@ def get_indexer(self, target, method=None, limit=None, tolerance=None):
                 start_plus_one = start + 1
                 if not ((start_plus_one < stop).any()):
                     return np.where(start_plus_one == stop, start, -1)
-            except TypeError:
-                pass
+            except TypeError as err:
+                # Only raise a type error when the types are not
+                # orderable, such as when the caller is combining
+                # an interval index with an integer index.
+                # (see test_append_different_columns_types_raises
+                # in pandas/tests/reshape/test_concat.py for more examples).
+                if err.args and 'unorderable types:' in err.args[0]:
+                    raise
 
         if not self.is_unique:
             raise ValueError("cannot handle non-unique indices")