From 75c915f9c72394c24fd96c936f5aee1f49e17ff2 Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Fri, 31 Jan 2020 23:13:15 -0600
Subject: [PATCH 01/58] Add test

---
 pandas/tests/arrays/test_boolean.py | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/pandas/tests/arrays/test_boolean.py b/pandas/tests/arrays/test_boolean.py
index cb9b07db4a0df..d5b9a5b0a3f10 100644
--- a/pandas/tests/arrays/test_boolean.py
+++ b/pandas/tests/arrays/test_boolean.py
@@ -929,3 +929,13 @@ def test_diff():
     result = s.diff()
     expected = pd.Series(expected)
     tm.assert_series_equal(result, expected)
+
+
+def test_nullable_boolean_filter():
+    s = pd.Series([1, 2, 3])
+    mask = pd.array([True, True, None], dtype="boolean")
+
+    result = s[mask]
+    expected = s.iloc[:2]
+
+    tm.assert_series_equal(result, expected)

From 9c5b9f06f54e570134a846dfde488c5c7b720671 Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Sun, 2 Feb 2020 17:53:52 -0600
Subject: [PATCH 02/58] Remove test that checks for error

---
 pandas/tests/indexing/test_na_indexing.py | 18 ------------------
 1 file changed, 18 deletions(-)

diff --git a/pandas/tests/indexing/test_na_indexing.py b/pandas/tests/indexing/test_na_indexing.py
index befe4fee8ecf8..f1ccaacfec049 100644
--- a/pandas/tests/indexing/test_na_indexing.py
+++ b/pandas/tests/indexing/test_na_indexing.py
@@ -59,21 +59,3 @@ def test_series_mask_boolean(values, dtype, mask, box_mask, frame):
 
     result = ser.loc[mask]
     tm.assert_equal(result, expected)
-
-
-@pytest.mark.parametrize("frame", [True, False])
-def test_indexing_with_na_raises(frame):
-    s = pd.Series([1, 2, 3], name="name")
-
-    if frame:
-        s = s.to_frame()
-    mask = pd.array([True, False, None], dtype="boolean")
-    match = "cannot mask with array containing NA / NaN values"
-    with pytest.raises(ValueError, match=match):
-        s[mask]
-
-    with pytest.raises(ValueError, match=match):
-        s.loc[mask]
-
-    with pytest.raises(ValueError, match=match):
-        s.iloc[mask]

From 2441b40a3eb1360134bb9843b8d2e05f30f09bba Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Sun, 2 Feb 2020 18:00:05 -0600
Subject: [PATCH 03/58] Add frame test

---
 pandas/tests/arrays/test_boolean.py | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/pandas/tests/arrays/test_boolean.py b/pandas/tests/arrays/test_boolean.py
index d5b9a5b0a3f10..01a9604edc580 100644
--- a/pandas/tests/arrays/test_boolean.py
+++ b/pandas/tests/arrays/test_boolean.py
@@ -931,7 +931,7 @@ def test_diff():
     tm.assert_series_equal(result, expected)
 
 
-def test_nullable_boolean_filter():
+def test_nullable_boolean_index_series():
     s = pd.Series([1, 2, 3])
     mask = pd.array([True, True, None], dtype="boolean")
 
@@ -939,3 +939,13 @@ def test_nullable_boolean_filter():
     expected = s.iloc[:2]
 
     tm.assert_series_equal(result, expected)
+
+
+def test_nullable_boolean_index_frame():
+    df = pd.DataFrame({"a": [1, 2, 3]})
+    mask = pd.array([True, True, None], dtype="boolean")
+
+    result = df[mask]
+    expected = df.iloc[:2, :]
+
+    tm.assert_frame_equal(result, expected)

From d71d1ba7ba7ceb3f95d5f2bed3aa819724a1c74d Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Sun, 2 Feb 2020 18:02:32 -0600
Subject: [PATCH 04/58] Don't raise with nullable boolean

---
 pandas/core/common.py   | 6 ------
 pandas/core/indexing.py | 7 +++++++
 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/pandas/core/common.py b/pandas/core/common.py
index a76119da2707a..ea0a219e9537d 100644
--- a/pandas/core/common.py
+++ b/pandas/core/common.py
@@ -114,7 +114,6 @@ def is_bool_indexer(key: Any) -> bool:
     check_array_indexer : Check that `key` is a valid array to index,
         and convert to an ndarray.
     """
-    na_msg = "cannot mask with array containing NA / NaN values"
     if isinstance(key, (ABCSeries, np.ndarray, ABCIndex)) or (
         is_array_like(key) and is_extension_array_dtype(key.dtype)
     ):
@@ -127,11 +126,6 @@ def is_bool_indexer(key: Any) -> bool:
                 return False
             return True
         elif is_bool_dtype(key.dtype):
-            # an ndarray with bool-dtype by definition has no missing values.
-            # So we only need to check for NAs in ExtensionArrays
-            if is_extension_array_dtype(key.dtype):
-                if np.any(key.isna()):
-                    raise ValueError(na_msg)
             return True
     elif isinstance(key, list):
         try:
diff --git a/pandas/core/indexing.py b/pandas/core/indexing.py
index 7e56148b7569e..4a60e3ff6d24f 100755
--- a/pandas/core/indexing.py
+++ b/pandas/core/indexing.py
@@ -8,6 +8,8 @@
 from pandas.util._decorators import Appender
 
 from pandas.core.dtypes.common import (
+    is_bool_dtype,
+    is_extension_array_dtype,
     is_float,
     is_integer,
     is_iterator,
@@ -2229,6 +2231,11 @@ def check_bool_indexer(index: Index, key) -> np.ndarray:
                 "the indexed object do not match)."
             )
         result = result.astype(bool)._values
+    elif is_extension_array_dtype(key) and is_bool_dtype(key):
+        mask = isna(key)
+        if mask.any():
+            result[mask] = False
+        result = np.asarray(result, dtype=bool)
     else:
         # key might be sparse / object-dtype bool, check_array_indexer needs bool array
         result = np.asarray(result, dtype=bool)

From 4d3a264f47497f03f51795e964395118d618e77e Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Sun, 2 Feb 2020 18:10:53 -0600
Subject: [PATCH 05/58] Don't modify result

---
 pandas/core/indexing.py | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/pandas/core/indexing.py b/pandas/core/indexing.py
index 4a60e3ff6d24f..dcf9c676e99de 100755
--- a/pandas/core/indexing.py
+++ b/pandas/core/indexing.py
@@ -2234,8 +2234,9 @@ def check_bool_indexer(index: Index, key) -> np.ndarray:
     elif is_extension_array_dtype(key) and is_bool_dtype(key):
         mask = isna(key)
         if mask.any():
-            result[mask] = False
-        result = np.asarray(result, dtype=bool)
+            result = np.asarray(np.where(~mask, result, False), dtype=bool)
+        else:
+            result = np.asarray(result, dtype=bool)
     else:
         # key might be sparse / object-dtype bool, check_array_indexer needs bool array
         result = np.asarray(result, dtype=bool)

From 543ef9ab262e1004e967f112d4a37927f10ebe7f Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Sun, 2 Feb 2020 18:11:12 -0600
Subject: [PATCH 06/58] Add frame test

---
 pandas/tests/arrays/test_boolean.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/pandas/tests/arrays/test_boolean.py b/pandas/tests/arrays/test_boolean.py
index 01a9604edc580..b3dc4dbc11b3d 100644
--- a/pandas/tests/arrays/test_boolean.py
+++ b/pandas/tests/arrays/test_boolean.py
@@ -931,7 +931,7 @@ def test_diff():
     tm.assert_series_equal(result, expected)
 
 
-def test_nullable_boolean_index_series():
+def test_nullable_boolean_mask_series():
     s = pd.Series([1, 2, 3])
     mask = pd.array([True, True, None], dtype="boolean")
 
@@ -941,7 +941,7 @@ def test_nullable_boolean_index_series():
     tm.assert_series_equal(result, expected)
 
 
-def test_nullable_boolean_index_frame():
+def test_nullable_boolean_mask_frame():
     df = pd.DataFrame({"a": [1, 2, 3]})
     mask = pd.array([True, True, None], dtype="boolean")
 

From d3e7a6909207f93e9e172cdc93bb6c0217f2badf Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Sun, 2 Feb 2020 18:16:42 -0600
Subject: [PATCH 07/58] Update whatsnew

---
 doc/source/whatsnew/v1.1.0.rst | 1 +
 1 file changed, 1 insertion(+)

diff --git a/doc/source/whatsnew/v1.1.0.rst b/doc/source/whatsnew/v1.1.0.rst
index e07a8fa0469f4..f47038ff8300c 100644
--- a/doc/source/whatsnew/v1.1.0.rst
+++ b/doc/source/whatsnew/v1.1.0.rst
@@ -202,6 +202,7 @@ Sparse
 ExtensionArray
 ^^^^^^^^^^^^^^
 
+- Enabled filtering with nullable Boolean arrays. (:issue:`31503`)
 -
 -
 

From ad7ae6684b99636ac17b65a3bc79671f695fb8f2 Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Sun, 2 Feb 2020 20:04:37 -0600
Subject: [PATCH 08/58] Fill NA

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

diff --git a/pandas/core/indexing.py b/pandas/core/indexing.py
index dcf9c676e99de..bf96bd09b77b4 100755
--- a/pandas/core/indexing.py
+++ b/pandas/core/indexing.py
@@ -2234,9 +2234,9 @@ def check_bool_indexer(index: Index, key) -> np.ndarray:
     elif is_extension_array_dtype(key) and is_bool_dtype(key):
         mask = isna(key)
         if mask.any():
-            result = np.asarray(np.where(~mask, result, False), dtype=bool)
+            result = np.asarray(key.fillna(False), dtype=bool)
         else:
-            result = np.asarray(result, dtype=bool)
+            result = np.asarray(key, dtype=bool)
     else:
         # key might be sparse / object-dtype bool, check_array_indexer needs bool array
         result = np.asarray(result, dtype=bool)

From f6e9ce598ffa103159b9a6b6fb3b13a2730ebc0c Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Mon, 3 Feb 2020 12:24:50 -0600
Subject: [PATCH 09/58] Remove some more tests

---
 pandas/tests/arrays/categorical/test_indexing.py | 11 -----------
 pandas/tests/extension/base/getitem.py           | 16 ----------------
 2 files changed, 27 deletions(-)

diff --git a/pandas/tests/arrays/categorical/test_indexing.py b/pandas/tests/arrays/categorical/test_indexing.py
index 85d5a6a3dc3ac..652ae2a9dde87 100644
--- a/pandas/tests/arrays/categorical/test_indexing.py
+++ b/pandas/tests/arrays/categorical/test_indexing.py
@@ -239,17 +239,6 @@ def test_mask_with_boolean(index):
     tm.assert_series_equal(result, expected)
 
 
-@pytest.mark.parametrize("index", [True, False])
-def test_mask_with_boolean_raises(index):
-    s = Series(range(3))
-    idx = Categorical([True, False, None])
-    if index:
-        idx = CategoricalIndex(idx)
-
-    with pytest.raises(ValueError, match="NA / NaN"):
-        s[idx]
-
-
 @pytest.fixture
 def non_coercible_categorical(monkeypatch):
     """
diff --git a/pandas/tests/extension/base/getitem.py b/pandas/tests/extension/base/getitem.py
index 8615a8df22dcc..50be6494a8e63 100644
--- a/pandas/tests/extension/base/getitem.py
+++ b/pandas/tests/extension/base/getitem.py
@@ -158,22 +158,6 @@ def test_getitem_boolean_array_mask(self, data):
         result = pd.Series(data)[mask]
         self.assert_series_equal(result, expected)
 
-    def test_getitem_boolean_array_mask_raises(self, data):
-        mask = pd.array(np.zeros(data.shape, dtype="bool"), dtype="boolean")
-        mask[:2] = pd.NA
-
-        msg = (
-            "Cannot mask with a boolean indexer containing NA values|"
-            "cannot mask with array containing NA / NaN values"
-        )
-        with pytest.raises(ValueError, match=msg):
-            data[mask]
-
-        s = pd.Series(data)
-
-        with pytest.raises(ValueError):
-            s[mask]
-
     @pytest.mark.parametrize(
         "idx",
         [[0, 1, 2], pd.array([0, 1, 2], dtype="Int64"), np.array([0, 1, 2])],

From 12344071edfcbe84007457ad0f812fe367dbc67b Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Mon, 3 Feb 2020 12:49:25 -0600
Subject: [PATCH 10/58] Delete another test

---
 pandas/tests/series/indexing/test_boolean.py | 8 --------
 1 file changed, 8 deletions(-)

diff --git a/pandas/tests/series/indexing/test_boolean.py b/pandas/tests/series/indexing/test_boolean.py
index 28f3c0f7429f8..b78dd2fc84f12 100644
--- a/pandas/tests/series/indexing/test_boolean.py
+++ b/pandas/tests/series/indexing/test_boolean.py
@@ -70,14 +70,6 @@ def test_getitem_boolean_object(string_series):
     s2[mask] = 5
     tm.assert_series_equal(cop, s2)
 
-    # nans raise exception
-    omask[5:10] = np.nan
-    msg = "cannot mask with array containing NA / NaN values"
-    with pytest.raises(ValueError, match=msg):
-        s[omask]
-    with pytest.raises(ValueError, match=msg):
-        s[omask] = 5
-
 
 def test_getitem_setitem_boolean_corner(datetime_series):
     ts = datetime_series

From 9b7e87936f84678e74c4a955017c28b0d3b146f0 Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Mon, 3 Feb 2020 17:35:36 -0600
Subject: [PATCH 11/58] Use to_numpy

---
 pandas/core/indexing.py | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/pandas/core/indexing.py b/pandas/core/indexing.py
index 77ce84509a25b..3785ecbd07818 100755
--- a/pandas/core/indexing.py
+++ b/pandas/core/indexing.py
@@ -2225,11 +2225,7 @@ def check_bool_indexer(index: Index, key) -> np.ndarray:
             )
         result = result.astype(bool)._values
     elif is_extension_array_dtype(key) and is_bool_dtype(key):
-        mask = isna(key)
-        if mask.any():
-            result = np.asarray(key.fillna(False), dtype=bool)
-        else:
-            result = np.asarray(key, dtype=bool)
+        result = key.to_numpy(dtype=bool, na_value=False)
     else:
         # key might be sparse / object-dtype bool, check_array_indexer needs bool array
         result = np.asarray(result, dtype=bool)

From efdd29a9284646f61de00f7ecb6ebd6eae390b24 Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Mon, 3 Feb 2020 17:56:32 -0600
Subject: [PATCH 12/58] Update whatsnew

---
 doc/source/whatsnew/v1.1.0.rst | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/doc/source/whatsnew/v1.1.0.rst b/doc/source/whatsnew/v1.1.0.rst
index 52bd13eff3bc1..d7c1864d21fb2 100644
--- a/doc/source/whatsnew/v1.1.0.rst
+++ b/doc/source/whatsnew/v1.1.0.rst
@@ -36,6 +36,11 @@ For example:
    ser["2014"]
    ser.loc["May 2015"]
 
+Indexing with Nullable Boolean Arrays
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Previously indexing with a nullable Boolean array would raise a ``ValueError``, however this is now permitted with ``NA`` being treated as ``False``. (:issue:`31503`)
+
 .. _whatsnew_110.enhancements.other:
 
 Other enhancements
@@ -212,7 +217,6 @@ Sparse
 ExtensionArray
 ^^^^^^^^^^^^^^
 
-- Enabled filtering with nullable Boolean arrays. (:issue:`31503`)
 -
 -
 

From 7fa36b6a3fd051412d9af46d97ab616eb98830aa Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Mon, 3 Feb 2020 17:59:18 -0600
Subject: [PATCH 13/58] Don't check for NA

---
 pandas/core/common.py | 2 --
 1 file changed, 2 deletions(-)

diff --git a/pandas/core/common.py b/pandas/core/common.py
index e7b1d1097a085..9b1394daf671f 100644
--- a/pandas/core/common.py
+++ b/pandas/core/common.py
@@ -121,8 +121,6 @@ def is_bool_indexer(key: Any) -> bool:
             key = np.asarray(values_from_object(key))
 
             if not lib.is_bool_array(key):
-                if isna(key).any():
-                    raise ValueError(na_msg)
                 return False
             return True
         elif is_bool_dtype(key.dtype):

From b8e3d6b11957ee3d8ad1f2c2e8ab25484c6c18a9 Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Mon, 3 Feb 2020 18:30:50 -0600
Subject: [PATCH 14/58] Revert "Remove test that checks for error"

This reverts commit 9c5b9f06f54e570134a846dfde488c5c7b720671.
---
 pandas/tests/indexing/test_na_indexing.py | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/pandas/tests/indexing/test_na_indexing.py b/pandas/tests/indexing/test_na_indexing.py
index f1ccaacfec049..befe4fee8ecf8 100644
--- a/pandas/tests/indexing/test_na_indexing.py
+++ b/pandas/tests/indexing/test_na_indexing.py
@@ -59,3 +59,21 @@ def test_series_mask_boolean(values, dtype, mask, box_mask, frame):
 
     result = ser.loc[mask]
     tm.assert_equal(result, expected)
+
+
+@pytest.mark.parametrize("frame", [True, False])
+def test_indexing_with_na_raises(frame):
+    s = pd.Series([1, 2, 3], name="name")
+
+    if frame:
+        s = s.to_frame()
+    mask = pd.array([True, False, None], dtype="boolean")
+    match = "cannot mask with array containing NA / NaN values"
+    with pytest.raises(ValueError, match=match):
+        s[mask]
+
+    with pytest.raises(ValueError, match=match):
+        s.loc[mask]
+
+    with pytest.raises(ValueError, match=match):
+        s.iloc[mask]

From bc3fe3f0c2c9a2f1f51e46bf0fd6f0e4a4794c54 Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Mon, 3 Feb 2020 18:40:04 -0600
Subject: [PATCH 15/58] Update NA test

---
 pandas/tests/indexing/test_na_indexing.py | 26 ++++++++++++++++-------
 1 file changed, 18 insertions(+), 8 deletions(-)

diff --git a/pandas/tests/indexing/test_na_indexing.py b/pandas/tests/indexing/test_na_indexing.py
index befe4fee8ecf8..4a9c93d753cc7 100644
--- a/pandas/tests/indexing/test_na_indexing.py
+++ b/pandas/tests/indexing/test_na_indexing.py
@@ -62,18 +62,28 @@ def test_series_mask_boolean(values, dtype, mask, box_mask, frame):
 
 
 @pytest.mark.parametrize("frame", [True, False])
-def test_indexing_with_na_raises(frame):
+def test_na_treated_as_false(frame):
     s = pd.Series([1, 2, 3], name="name")
 
     if frame:
         s = s.to_frame()
+
     mask = pd.array([True, False, None], dtype="boolean")
-    match = "cannot mask with array containing NA / NaN values"
-    with pytest.raises(ValueError, match=match):
-        s[mask]
 
-    with pytest.raises(ValueError, match=match):
-        s.loc[mask]
+    result = s[mask]
+    expected = s[mask.fillna(False)]
+
+    result_loc = s.loc[mask]
+    expected_loc = s.loc[mask.fillna(False)]
 
-    with pytest.raises(ValueError, match=match):
-        s.iloc[mask]
+    result_iloc = s.iloc[mask]
+    expected_iloc = s.iloc[mask.fillna(False)]
+
+    if frame:
+        tm.assert_frame_equal(result, expected)
+        tm.assert_frame_equal(result_loc, expected_loc)
+        tm.assert_frame_equal(result_iloc, expected_iloc)
+    else:
+        tm.assert_series_equal(result, expected)
+        tm.assert_series_equal(result_loc, expected_loc)
+        tm.assert_series_equal(result_iloc, expected_iloc)

From 73ad2211ac0ad37a502d8eee52805d6f87ae7454 Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Mon, 3 Feb 2020 18:45:42 -0600
Subject: [PATCH 16/58] Revert "Remove some more tests"

This reverts commit f6e9ce598ffa103159b9a6b6fb3b13a2730ebc0c.
---
 pandas/tests/arrays/categorical/test_indexing.py | 11 +++++++++++
 pandas/tests/extension/base/getitem.py           | 16 ++++++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/pandas/tests/arrays/categorical/test_indexing.py b/pandas/tests/arrays/categorical/test_indexing.py
index 652ae2a9dde87..85d5a6a3dc3ac 100644
--- a/pandas/tests/arrays/categorical/test_indexing.py
+++ b/pandas/tests/arrays/categorical/test_indexing.py
@@ -239,6 +239,17 @@ def test_mask_with_boolean(index):
     tm.assert_series_equal(result, expected)
 
 
+@pytest.mark.parametrize("index", [True, False])
+def test_mask_with_boolean_raises(index):
+    s = Series(range(3))
+    idx = Categorical([True, False, None])
+    if index:
+        idx = CategoricalIndex(idx)
+
+    with pytest.raises(ValueError, match="NA / NaN"):
+        s[idx]
+
+
 @pytest.fixture
 def non_coercible_categorical(monkeypatch):
     """
diff --git a/pandas/tests/extension/base/getitem.py b/pandas/tests/extension/base/getitem.py
index 50be6494a8e63..8615a8df22dcc 100644
--- a/pandas/tests/extension/base/getitem.py
+++ b/pandas/tests/extension/base/getitem.py
@@ -158,6 +158,22 @@ def test_getitem_boolean_array_mask(self, data):
         result = pd.Series(data)[mask]
         self.assert_series_equal(result, expected)
 
+    def test_getitem_boolean_array_mask_raises(self, data):
+        mask = pd.array(np.zeros(data.shape, dtype="bool"), dtype="boolean")
+        mask[:2] = pd.NA
+
+        msg = (
+            "Cannot mask with a boolean indexer containing NA values|"
+            "cannot mask with array containing NA / NaN values"
+        )
+        with pytest.raises(ValueError, match=msg):
+            data[mask]
+
+        s = pd.Series(data)
+
+        with pytest.raises(ValueError):
+            s[mask]
+
     @pytest.mark.parametrize(
         "idx",
         [[0, 1, 2], pd.array([0, 1, 2], dtype="Int64"), np.array([0, 1, 2])],

From 547d7bc7cd1fdbd38320723fb28c4a4906e51366 Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Mon, 3 Feb 2020 18:51:07 -0600
Subject: [PATCH 17/58] Update Categorical test

Not sure how applicable the CategoricalIndex part is
here so going to remove for now
---
 pandas/tests/arrays/categorical/test_indexing.py | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/pandas/tests/arrays/categorical/test_indexing.py b/pandas/tests/arrays/categorical/test_indexing.py
index 85d5a6a3dc3ac..b01c5d5f178c5 100644
--- a/pandas/tests/arrays/categorical/test_indexing.py
+++ b/pandas/tests/arrays/categorical/test_indexing.py
@@ -239,15 +239,14 @@ def test_mask_with_boolean(index):
     tm.assert_series_equal(result, expected)
 
 
-@pytest.mark.parametrize("index", [True, False])
-def test_mask_with_boolean_raises(index):
+def test_mask_with_boolean_na_treated_as_false():
     s = Series(range(3))
     idx = Categorical([True, False, None])
-    if index:
-        idx = CategoricalIndex(idx)
 
-    with pytest.raises(ValueError, match="NA / NaN"):
-        s[idx]
+    result = s[idx]
+    expected = s[idx.fillna(False)]
+
+    tm.assert_series_equal(result, expected)
 
 
 @pytest.fixture

From 5649445e86e1d3e553823efba187661725c9eab3 Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Mon, 3 Feb 2020 18:56:08 -0600
Subject: [PATCH 18/58] Update getitem tests

---
 pandas/tests/extension/base/getitem.py | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/pandas/tests/extension/base/getitem.py b/pandas/tests/extension/base/getitem.py
index 8615a8df22dcc..cfa883a07eed0 100644
--- a/pandas/tests/extension/base/getitem.py
+++ b/pandas/tests/extension/base/getitem.py
@@ -158,21 +158,21 @@ def test_getitem_boolean_array_mask(self, data):
         result = pd.Series(data)[mask]
         self.assert_series_equal(result, expected)
 
-    def test_getitem_boolean_array_mask_raises(self, data):
+    def test_getitem_boolean_na_treated_as_false(self, data):
         mask = pd.array(np.zeros(data.shape, dtype="bool"), dtype="boolean")
         mask[:2] = pd.NA
 
-        msg = (
-            "Cannot mask with a boolean indexer containing NA values|"
-            "cannot mask with array containing NA / NaN values"
-        )
-        with pytest.raises(ValueError, match=msg):
-            data[mask]
+        result = data[mask]
+        expected = data[mask.fillna(False)]
+
+        tm.assert_frame_equal(result, expected)
 
         s = pd.Series(data)
 
-        with pytest.raises(ValueError):
-            s[mask]
+        result = s[mask]
+        expected = s[mask.fillna(False)]
+
+        tm.assert_series_equal(result, expected)
 
     @pytest.mark.parametrize(
         "idx",

From bb3d143f8b769f79b6cdfb95a74196cc29150e85 Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Mon, 3 Feb 2020 19:55:07 -0600
Subject: [PATCH 19/58] Update indexers.py

---
 pandas/core/indexers.py | 23 ++++++++++++++---------
 1 file changed, 14 insertions(+), 9 deletions(-)

diff --git a/pandas/core/indexers.py b/pandas/core/indexers.py
index fe475527f4596..6da2150595a09 100644
--- a/pandas/core/indexers.py
+++ b/pandas/core/indexers.py
@@ -10,6 +10,7 @@
 from pandas.core.dtypes.common import (
     is_array_like,
     is_bool_dtype,
+    is_extension_array_dtype,
     is_integer_dtype,
     is_list_like,
 )
@@ -333,14 +334,11 @@ def check_array_indexer(array: AnyArrayLike, indexer: Any) -> Any:
     ...
     IndexError: Boolean index has wrong length: 3 instead of 2.
 
-    A ValueError is raised when the mask cannot be converted to
-    a bool-dtype ndarray.
+    NA values are treated as False.
 
     >>> mask = pd.array([True, pd.NA])
     >>> pd.api.indexers.check_array_indexer(arr, mask)
-    Traceback (most recent call last):
-    ...
-    ValueError: Cannot mask with a boolean indexer containing NA values
+    array([ True, False])
 
     A numpy boolean mask will get passed through (if the length is correct):
 
@@ -392,10 +390,17 @@ def check_array_indexer(array: AnyArrayLike, indexer: Any) -> Any:
 
     dtype = indexer.dtype
     if is_bool_dtype(dtype):
-        try:
-            indexer = np.asarray(indexer, dtype=bool)
-        except ValueError:
-            raise ValueError("Cannot mask with a boolean indexer containing NA values")
+        if is_extension_array_dtype(dtype):
+            indexer = indexer.to_numpy(dtype=bool, na_value=False)
+        else:
+            try:
+                indexer = np.asarray(indexer, dtype=bool)
+            except ValueError:
+                msg = (
+                    "Cannot mask with a non-ExtensionArray boolean indexer "
+                    " containing missing values"
+                )
+                raise ValueError(msg)
 
         # GH26658
         if len(indexer) != len(array):

From f107252431710d535aa9a5652ad852e05571bb29 Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Mon, 3 Feb 2020 20:19:16 -0600
Subject: [PATCH 20/58] tm -> self

---
 pandas/tests/extension/base/getitem.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/pandas/tests/extension/base/getitem.py b/pandas/tests/extension/base/getitem.py
index cfa883a07eed0..eb0f0e91e8fe6 100644
--- a/pandas/tests/extension/base/getitem.py
+++ b/pandas/tests/extension/base/getitem.py
@@ -165,14 +165,14 @@ def test_getitem_boolean_na_treated_as_false(self, data):
         result = data[mask]
         expected = data[mask.fillna(False)]
 
-        tm.assert_frame_equal(result, expected)
+        self.assert_frame_equal(result, expected)
 
         s = pd.Series(data)
 
         result = s[mask]
         expected = s[mask.fillna(False)]
 
-        tm.assert_series_equal(result, expected)
+        self.assert_series_equal(result, expected)
 
     @pytest.mark.parametrize(
         "idx",

From 7b924b7ca4f6fc15a1b071d7553a3b6ceb23e50d Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Mon, 3 Feb 2020 20:23:22 -0600
Subject: [PATCH 21/58] Assert for EA not DataFrame

---
 pandas/tests/extension/base/getitem.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/tests/extension/base/getitem.py b/pandas/tests/extension/base/getitem.py
index eb0f0e91e8fe6..aa1fbbb41bfb9 100644
--- a/pandas/tests/extension/base/getitem.py
+++ b/pandas/tests/extension/base/getitem.py
@@ -165,7 +165,7 @@ def test_getitem_boolean_na_treated_as_false(self, data):
         result = data[mask]
         expected = data[mask.fillna(False)]
 
-        self.assert_frame_equal(result, expected)
+        self.assert_extension_array_equal(result, expected)
 
         s = pd.Series(data)
 

From 46d77dfc39d426971a2a9fc6ad5e594ed75e2ebb Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Tue, 4 Feb 2020 12:50:09 -0600
Subject: [PATCH 22/58] Don't try / except

---
 pandas/core/indexers.py | 9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

diff --git a/pandas/core/indexers.py b/pandas/core/indexers.py
index 6da2150595a09..8b7716707bb04 100644
--- a/pandas/core/indexers.py
+++ b/pandas/core/indexers.py
@@ -393,14 +393,7 @@ def check_array_indexer(array: AnyArrayLike, indexer: Any) -> Any:
         if is_extension_array_dtype(dtype):
             indexer = indexer.to_numpy(dtype=bool, na_value=False)
         else:
-            try:
-                indexer = np.asarray(indexer, dtype=bool)
-            except ValueError:
-                msg = (
-                    "Cannot mask with a non-ExtensionArray boolean indexer "
-                    " containing missing values"
-                )
-                raise ValueError(msg)
+            indexer = np.asarray(indexer, dtype=bool)
 
         # GH26658
         if len(indexer) != len(array):

From ac71cbf1bf3dae6e1114e9578543711ed8046789 Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Tue, 4 Feb 2020 12:50:37 -0600
Subject: [PATCH 23/58] Change check_indexer test

Removed the test on [True, False, None] which is no longer raising.
Not clear to me what the correct behavior should be, but this is now
returning a pandas array with pd.NA instead of None.
---
 pandas/tests/indexing/test_check_indexer.py | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/pandas/tests/indexing/test_check_indexer.py b/pandas/tests/indexing/test_check_indexer.py
index 82f8c12229824..0275a286bff29 100644
--- a/pandas/tests/indexing/test_check_indexer.py
+++ b/pandas/tests/indexing/test_check_indexer.py
@@ -31,15 +31,16 @@ def test_valid_input(indexer, expected):
     tm.assert_numpy_array_equal(result, expected)
 
 
-@pytest.mark.parametrize(
-    "indexer", [[True, False, None], pd.array([True, False, None], dtype="boolean")],
-)
-def test_bool_raise_missing_values(indexer):
-    array = np.array([1, 2, 3])
+def test_boolean_na_returns_indexer():
+    # TODO: What to do now about list input that contains
+    # bools and None?
+    arr = np.array([1, 2, 3])
+    indexer = pd.array([True, False, None], dtype="boolean")
 
-    msg = "Cannot mask with a boolean indexer containing NA values"
-    with pytest.raises(ValueError, match=msg):
-        check_array_indexer(array, indexer)
+    result = check_array_indexer(arr, indexer)
+    expected = np.array([True, False, False], dtype=bool)
+
+    tm.assert_numpy_array_equal(result, expected)
 
 
 @pytest.mark.parametrize(

From e5ed092fd8a7af391c09525918ffe4e3e14f5f1d Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Tue, 4 Feb 2020 16:48:59 -0600
Subject: [PATCH 24/58] Modify __getitem__ for datetimelike

---
 pandas/core/arrays/datetimelike.py | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/pandas/core/arrays/datetimelike.py b/pandas/core/arrays/datetimelike.py
index 4f14ac2a14157..22b2dffb4e97b 100644
--- a/pandas/core/arrays/datetimelike.py
+++ b/pandas/core/arrays/datetimelike.py
@@ -24,6 +24,7 @@
     is_datetime64tz_dtype,
     is_datetime_or_timedelta_dtype,
     is_dtype_equal,
+    is_extension_array_dtype,
     is_float_dtype,
     is_integer_dtype,
     is_list_like,
@@ -520,7 +521,11 @@ def __getitem__(self, key):
         if com.is_bool_indexer(key):
             # first convert to boolean, because check_array_indexer doesn't
             # allow object dtype
-            key = np.asarray(key, dtype=bool)
+            if is_extension_array_dtype(key):
+                key = key.to_numpy(dtype=bool, na_value=False)
+            else:
+                key = np.asarray(key, dtype=bool)
+
             key = check_array_indexer(self, key)
             if key.all():
                 key = slice(0, None, None)

From 9fcdb23b82d0959307aa8677927ecc6f4f5579b7 Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Tue, 4 Feb 2020 17:10:12 -0600
Subject: [PATCH 25/58] Add back ValueError for non-boolean with NA

---
 pandas/core/common.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/pandas/core/common.py b/pandas/core/common.py
index 9b1394daf671f..345a4fbc308d8 100644
--- a/pandas/core/common.py
+++ b/pandas/core/common.py
@@ -121,6 +121,9 @@ def is_bool_indexer(key: Any) -> bool:
             key = np.asarray(values_from_object(key))
 
             if not lib.is_bool_array(key):
+                na_msg = "Cannot mask with non-boolean array containing NA / NaN values"
+                if isna(key).any():
+                    raise ValueError(na_msg)
                 return False
             return True
         elif is_bool_dtype(key.dtype):

From c2dfa93a522e3c784dde562a06c911b61e12a619 Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Tue, 4 Feb 2020 17:30:07 -0600
Subject: [PATCH 26/58] Revert "Delete another test"

This reverts commit 12344071edfcbe84007457ad0f812fe367dbc67b.
---
 pandas/tests/series/indexing/test_boolean.py | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/pandas/tests/series/indexing/test_boolean.py b/pandas/tests/series/indexing/test_boolean.py
index b78dd2fc84f12..28f3c0f7429f8 100644
--- a/pandas/tests/series/indexing/test_boolean.py
+++ b/pandas/tests/series/indexing/test_boolean.py
@@ -70,6 +70,14 @@ def test_getitem_boolean_object(string_series):
     s2[mask] = 5
     tm.assert_series_equal(cop, s2)
 
+    # nans raise exception
+    omask[5:10] = np.nan
+    msg = "cannot mask with array containing NA / NaN values"
+    with pytest.raises(ValueError, match=msg):
+        s[omask]
+    with pytest.raises(ValueError, match=msg):
+        s[omask] = 5
+
 
 def test_getitem_setitem_boolean_corner(datetime_series):
     ts = datetime_series

From a9a12b19f85e3c61d253093d8859f659ed9463e6 Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Tue, 4 Feb 2020 17:31:49 -0600
Subject: [PATCH 27/58] Fixup error message

---
 pandas/tests/series/indexing/test_boolean.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/tests/series/indexing/test_boolean.py b/pandas/tests/series/indexing/test_boolean.py
index 28f3c0f7429f8..8878a4a6526af 100644
--- a/pandas/tests/series/indexing/test_boolean.py
+++ b/pandas/tests/series/indexing/test_boolean.py
@@ -72,7 +72,7 @@ def test_getitem_boolean_object(string_series):
 
     # nans raise exception
     omask[5:10] = np.nan
-    msg = "cannot mask with array containing NA / NaN values"
+    msg = "Cannot mask with non-boolean array containing NA / NaN values"
     with pytest.raises(ValueError, match=msg):
         s[omask]
     with pytest.raises(ValueError, match=msg):

From 7c10f33643c54cb732b8c3bd41850a646f3e9899 Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Tue, 4 Feb 2020 21:04:13 -0600
Subject: [PATCH 28/58] Add before and after examples

---
 doc/source/whatsnew/v1.1.0.rst | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/doc/source/whatsnew/v1.1.0.rst b/doc/source/whatsnew/v1.1.0.rst
index d7c1864d21fb2..6d1c9a6b8a2ab 100644
--- a/doc/source/whatsnew/v1.1.0.rst
+++ b/doc/source/whatsnew/v1.1.0.rst
@@ -41,6 +41,26 @@ Indexing with Nullable Boolean Arrays
 
 Previously indexing with a nullable Boolean array would raise a ``ValueError``, however this is now permitted with ``NA`` being treated as ``False``. (:issue:`31503`)
 
+*pandas 1.0.x*
+
+.. code-block:: python
+
+    >>> s = pd.Series([1, 2, 3, 4])
+    >>> mask = pd.array([True, True, False, None], dtype="boolean")
+    >>> s[mask]
+    Traceback (most recent call last):
+    ...
+    ValueError: cannot mask with array containing NA / NaN values
+
+*pandas 1.1.0*
+
+.. code-block:: python
+
+    >>> s[mask]
+    0    1
+    1    2
+    dtype: int64
+
 .. _whatsnew_110.enhancements.other:
 
 Other enhancements

From cf3d60de75aa2ead0f02b71adb262658e422a894 Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Tue, 4 Feb 2020 21:21:16 -0600
Subject: [PATCH 29/58] Get rid of some tests

---
 pandas/tests/arrays/test_boolean.py | 20 --------------------
 1 file changed, 20 deletions(-)

diff --git a/pandas/tests/arrays/test_boolean.py b/pandas/tests/arrays/test_boolean.py
index b3dc4dbc11b3d..cb9b07db4a0df 100644
--- a/pandas/tests/arrays/test_boolean.py
+++ b/pandas/tests/arrays/test_boolean.py
@@ -929,23 +929,3 @@ def test_diff():
     result = s.diff()
     expected = pd.Series(expected)
     tm.assert_series_equal(result, expected)
-
-
-def test_nullable_boolean_mask_series():
-    s = pd.Series([1, 2, 3])
-    mask = pd.array([True, True, None], dtype="boolean")
-
-    result = s[mask]
-    expected = s.iloc[:2]
-
-    tm.assert_series_equal(result, expected)
-
-
-def test_nullable_boolean_mask_frame():
-    df = pd.DataFrame({"a": [1, 2, 3]})
-    mask = pd.array([True, True, None], dtype="boolean")
-
-    result = df[mask]
-    expected = df.iloc[:2, :]
-
-    tm.assert_frame_equal(result, expected)

From 157d8b98d00e686b0437aa91b84341aa7f261ebc Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Tue, 4 Feb 2020 22:09:26 -0600
Subject: [PATCH 30/58] Cast another way

---
 pandas/core/arrays/datetimelike.py | 5 +----
 pandas/core/indexing.py            | 6 +++---
 2 files changed, 4 insertions(+), 7 deletions(-)

diff --git a/pandas/core/arrays/datetimelike.py b/pandas/core/arrays/datetimelike.py
index 22b2dffb4e97b..8544a2dcf1f49 100644
--- a/pandas/core/arrays/datetimelike.py
+++ b/pandas/core/arrays/datetimelike.py
@@ -24,7 +24,6 @@
     is_datetime64tz_dtype,
     is_datetime_or_timedelta_dtype,
     is_dtype_equal,
-    is_extension_array_dtype,
     is_float_dtype,
     is_integer_dtype,
     is_list_like,
@@ -521,9 +520,7 @@ def __getitem__(self, key):
         if com.is_bool_indexer(key):
             # first convert to boolean, because check_array_indexer doesn't
             # allow object dtype
-            if is_extension_array_dtype(key):
-                key = key.to_numpy(dtype=bool, na_value=False)
-            else:
+            if is_object_dtype(key):
                 key = np.asarray(key, dtype=bool)
 
             key = check_array_indexer(self, key)
diff --git a/pandas/core/indexing.py b/pandas/core/indexing.py
index 3785ecbd07818..90952e201e4d2 100755
--- a/pandas/core/indexing.py
+++ b/pandas/core/indexing.py
@@ -2224,12 +2224,12 @@ def check_bool_indexer(index: Index, key) -> np.ndarray:
                 "the indexed object do not match)."
             )
         result = result.astype(bool)._values
-    elif is_extension_array_dtype(key) and is_bool_dtype(key):
-        result = key.to_numpy(dtype=bool, na_value=False)
-    else:
+    elif is_object_dtype(key):
         # key might be sparse / object-dtype bool, check_array_indexer needs bool array
         result = np.asarray(result, dtype=bool)
         result = check_array_indexer(index, result)
+    else:
+        result = check_array_indexer(index, result)
 
     return result
 

From 250f22828a1044ddba0bf2363e3c3500a047a30d Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Wed, 5 Feb 2020 08:03:26 -0600
Subject: [PATCH 31/58] Import

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

diff --git a/pandas/core/indexing.py b/pandas/core/indexing.py
index 90952e201e4d2..81e69b245d5e2 100755
--- a/pandas/core/indexing.py
+++ b/pandas/core/indexing.py
@@ -15,6 +15,7 @@
     is_iterator,
     is_list_like,
     is_numeric_dtype,
+    is_object_dtype,
     is_scalar,
     is_sequence,
 )

From 647f0f63f10b9d346f4f79692ba5cf769b797927 Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Wed, 5 Feb 2020 09:41:22 -0600
Subject: [PATCH 32/58] Don't import unused

---
 pandas/core/indexing.py | 2 --
 1 file changed, 2 deletions(-)

diff --git a/pandas/core/indexing.py b/pandas/core/indexing.py
index 81e69b245d5e2..cb8575b49e37e 100755
--- a/pandas/core/indexing.py
+++ b/pandas/core/indexing.py
@@ -8,8 +8,6 @@
 from pandas.util._decorators import Appender
 
 from pandas.core.dtypes.common import (
-    is_bool_dtype,
-    is_extension_array_dtype,
     is_float,
     is_integer,
     is_iterator,

From a9e73deac9617e7eea12bf9aacc036605d2a1150 Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Mon, 10 Feb 2020 08:18:26 -0600
Subject: [PATCH 33/58] Update whatsnew

---
 doc/source/whatsnew/v1.1.0.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/doc/source/whatsnew/v1.1.0.rst b/doc/source/whatsnew/v1.1.0.rst
index 34779ef508149..fa53b89df5be0 100644
--- a/doc/source/whatsnew/v1.1.0.rst
+++ b/doc/source/whatsnew/v1.1.0.rst
@@ -39,7 +39,7 @@ For example:
 Indexing with Nullable Boolean Arrays
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-Previously indexing with a nullable Boolean array would raise a ``ValueError``, however this is now permitted with ``NA`` being treated as ``False``. (:issue:`31503`)
+Previously indexing with a nullable Boolean array containing ``NA`` would raise a ``ValueError``, however this is now permitted with ``NA`` being treated as ``False``. (:issue:`31503`)
 
 *pandas 1.0.x*
 

From adc307518db31dd4ee9c4408cdb2c87760eac4ba Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Mon, 10 Feb 2020 08:21:42 -0600
Subject: [PATCH 34/58] Update boolean.rst

---
 doc/source/user_guide/boolean.rst | 10 +---------
 1 file changed, 1 insertion(+), 9 deletions(-)

diff --git a/doc/source/user_guide/boolean.rst b/doc/source/user_guide/boolean.rst
index 5276bc6142206..3da2be09d2b7c 100644
--- a/doc/source/user_guide/boolean.rst
+++ b/doc/source/user_guide/boolean.rst
@@ -20,8 +20,7 @@ Nullable Boolean Data Type
 Indexing with NA values
 -----------------------
 
-pandas does not allow indexing with NA values. Attempting to do so
-will raise a ``ValueError``.
+pandas allows indexing with ``NA`` values, which are treated as ``False``.
 
 .. ipython:: python
    :okexcept:
@@ -30,13 +29,6 @@ will raise a ``ValueError``.
    mask = pd.array([True, False, pd.NA], dtype="boolean")
    s[mask]
 
-The missing values will need to be explicitly filled with True or False prior
-to using the array as a mask.
-
-.. ipython:: python
-
-   s[mask.fillna(False)]
-
 .. _boolean.kleene:
 
 Kleene Logical Operations

From 29ff823e6d4cc53ec2081a5e45fc0bb719d0bb59 Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Mon, 10 Feb 2020 08:24:06 -0600
Subject: [PATCH 35/58] check_array_indexer docstring

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

diff --git a/pandas/core/indexers.py b/pandas/core/indexers.py
index 8b7716707bb04..e9bdc99cef3ed 100644
--- a/pandas/core/indexers.py
+++ b/pandas/core/indexers.py
@@ -334,7 +334,7 @@ def check_array_indexer(array: AnyArrayLike, indexer: Any) -> Any:
     ...
     IndexError: Boolean index has wrong length: 3 instead of 2.
 
-    NA values are treated as False.
+    NA values in a boolean array are treated as False.
 
     >>> mask = pd.array([True, pd.NA])
     >>> pd.api.indexers.check_array_indexer(arr, mask)

From 0a58605193c48f5a70db26a6a700cad8e4a96ced Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Mon, 10 Feb 2020 08:34:26 -0600
Subject: [PATCH 36/58] Edit 1.1.0 whatsnew

---
 doc/source/whatsnew/v1.1.0.rst | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/doc/source/whatsnew/v1.1.0.rst b/doc/source/whatsnew/v1.1.0.rst
index fa53b89df5be0..8e6f213a6a58a 100644
--- a/doc/source/whatsnew/v1.1.0.rst
+++ b/doc/source/whatsnew/v1.1.0.rst
@@ -41,12 +41,17 @@ Indexing with Nullable Boolean Arrays
 
 Previously indexing with a nullable Boolean array containing ``NA`` would raise a ``ValueError``, however this is now permitted with ``NA`` being treated as ``False``. (:issue:`31503`)
 
+.. ipython:: python
+
+    s = pd.Series([1, 2, 3, 4])
+    mask = pd.array([True, True, False, None], dtype="boolean")
+    s
+    mask
+
 *pandas 1.0.x*
 
 .. code-block:: python
 
-    >>> s = pd.Series([1, 2, 3, 4])
-    >>> mask = pd.array([True, True, False, None], dtype="boolean")
     >>> s[mask]
     Traceback (most recent call last):
     ...
@@ -54,12 +59,9 @@ Previously indexing with a nullable Boolean array containing ``NA`` would raise
 
 *pandas 1.1.0*
 
-.. code-block:: python
+.. ipython:: python
 
-    >>> s[mask]
-    0    1
-    1    2
-    dtype: int64
+    s[mask]
 
 .. _whatsnew_110.enhancements.other:
 

From b38a20912f4bbd62848e466c9b7a583668f38e14 Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Mon, 10 Feb 2020 09:05:45 -0600
Subject: [PATCH 37/58] Add to indexing.rst

---
 doc/source/user_guide/indexing.rst | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/doc/source/user_guide/indexing.rst b/doc/source/user_guide/indexing.rst
index a8cdf4a61073d..cc17fcd9e4263 100644
--- a/doc/source/user_guide/indexing.rst
+++ b/doc/source/user_guide/indexing.rst
@@ -59,7 +59,7 @@ of multi-axis indexing.
       slices, **both** the start and the stop are included, when present in the
       index! See :ref:`Slicing with labels <indexing.slicing_with_labels>`
       and :ref:`Endpoints are inclusive <advanced.endpoints_are_inclusive>`.)
-    * A boolean array
+    * A boolean array (any ``NA`` values will be treated as ``False``).
     * A ``callable`` function with one argument (the calling Series or DataFrame) and
       that returns valid output for indexing (one of the above).
 
@@ -75,7 +75,7 @@ of multi-axis indexing.
     * An integer e.g. ``5``.
     * A list or array of integers ``[4, 3, 0]``.
     * A slice object with ints ``1:7``.
-    * A boolean array.
+    * A boolean array (any ``NA`` values will be treated as ``False``).
     * A ``callable`` function with one argument (the calling Series or DataFrame) and
       that returns valid output for indexing (one of the above).
 
@@ -374,6 +374,12 @@ For getting values with a boolean array:
    df1.loc['a'] > 0
    df1.loc[:, df1.loc['a'] > 0]
 
+NA values in a boolean array propogate as ``False``:
+
+   mask = pd.array([True, False, True, False, pd.NA, False], dtype="boolean")
+   mask
+   df1[mask]
+
 For getting a value explicitly:
 
 .. ipython:: python

From 5088cbb426684baab0bc87ca85f6d940fa5c7696 Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Mon, 10 Feb 2020 09:16:13 -0600
Subject: [PATCH 38/58] Add back index parameter

---
 pandas/tests/arrays/categorical/test_indexing.py | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/pandas/tests/arrays/categorical/test_indexing.py b/pandas/tests/arrays/categorical/test_indexing.py
index b01c5d5f178c5..a866eb08f1f4e 100644
--- a/pandas/tests/arrays/categorical/test_indexing.py
+++ b/pandas/tests/arrays/categorical/test_indexing.py
@@ -239,9 +239,12 @@ def test_mask_with_boolean(index):
     tm.assert_series_equal(result, expected)
 
 
-def test_mask_with_boolean_na_treated_as_false():
+@pytest.mark.parametrize("index", [True, False])
+def test_mask_with_boolean_na_treated_as_false(index):
     s = Series(range(3))
     idx = Categorical([True, False, None])
+    if index:
+        idx = CategoricalIndex(idx)
 
     result = s[idx]
     expected = s[idx.fillna(False)]

From 54efdd95a85cb330e296ffba2ed82409d245e3c0 Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Mon, 10 Feb 2020 09:19:49 -0600
Subject: [PATCH 39/58] Add some True values in test

---
 pandas/tests/extension/base/getitem.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/pandas/tests/extension/base/getitem.py b/pandas/tests/extension/base/getitem.py
index aa1fbbb41bfb9..d69efb90388e5 100644
--- a/pandas/tests/extension/base/getitem.py
+++ b/pandas/tests/extension/base/getitem.py
@@ -161,6 +161,7 @@ def test_getitem_boolean_array_mask(self, data):
     def test_getitem_boolean_na_treated_as_false(self, data):
         mask = pd.array(np.zeros(data.shape, dtype="bool"), dtype="boolean")
         mask[:2] = pd.NA
+        mask[2:4] = True
 
         result = data[mask]
         expected = data[mask.fillna(False)]

From c6b81ed1bdebdd360f9b50b28d89831ca21e9e15 Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Mon, 10 Feb 2020 10:09:50 -0600
Subject: [PATCH 40/58] Edit boolean.rst

---
 doc/source/user_guide/boolean.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/doc/source/user_guide/boolean.rst b/doc/source/user_guide/boolean.rst
index 3da2be09d2b7c..971fea2d6c9d3 100644
--- a/doc/source/user_guide/boolean.rst
+++ b/doc/source/user_guide/boolean.rst
@@ -20,7 +20,7 @@ Nullable Boolean Data Type
 Indexing with NA values
 -----------------------
 
-pandas allows indexing with ``NA`` values, which are treated as ``False``.
+pandas allows indexing with ``NA`` values in a boolean array, which are treated as ``False``.
 
 .. ipython:: python
    :okexcept:

From 67800c67b257e381b9aacf9bd751108cc03708b4 Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Mon, 10 Feb 2020 10:44:11 -0600
Subject: [PATCH 41/58] Add list back to check_array_indexer test

---
 pandas/tests/indexing/test_check_indexer.py | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/pandas/tests/indexing/test_check_indexer.py b/pandas/tests/indexing/test_check_indexer.py
index 0275a286bff29..64f841fdcc41b 100644
--- a/pandas/tests/indexing/test_check_indexer.py
+++ b/pandas/tests/indexing/test_check_indexer.py
@@ -31,11 +31,11 @@ def test_valid_input(indexer, expected):
     tm.assert_numpy_array_equal(result, expected)
 
 
-def test_boolean_na_returns_indexer():
-    # TODO: What to do now about list input that contains
-    # bools and None?
+@pytest.mark.parametrize(
+    "indexer", [[True, False, None], pd.array([True, False, None], dtype="boolean")],
+)
+def test_boolean_na_returns_indexer(indexer):
     arr = np.array([1, 2, 3])
-    indexer = pd.array([True, False, None], dtype="boolean")
 
     result = check_array_indexer(arr, indexer)
     expected = np.array([True, False, False], dtype=bool)

From 578fd3cdf134627013a084e703f6186d019eef75 Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Mon, 10 Feb 2020 14:54:12 -0600
Subject: [PATCH 42/58] Account for pd.NA in is_bool_indexer

---
 pandas/core/common.py | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/pandas/core/common.py b/pandas/core/common.py
index 526a9144ddcbf..1892e19dd3681 100644
--- a/pandas/core/common.py
+++ b/pandas/core/common.py
@@ -13,7 +13,7 @@
 
 import numpy as np
 
-from pandas._libs import lib, tslibs
+from pandas._libs import lib, tslibs, missing as libmissing
 from pandas._typing import T
 
 from pandas.core.dtypes.cast import construct_1d_object_array_from_listlike
@@ -133,11 +133,7 @@ def is_bool_indexer(key: Any) -> bool:
         elif is_bool_dtype(key.dtype):
             return True
     elif isinstance(key, list):
-        try:
-            arr = np.asarray(key)
-            return arr.dtype == np.bool_ and len(arr) == len(key)
-        except TypeError:  # pragma: no cover
-            return False
+        return all(k is libmissing.NA or k is True or k is False for k in key)
 
     return False
 

From a5593850b97f09fc72e9411851addcd433290b5c Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Mon, 10 Feb 2020 14:55:14 -0600
Subject: [PATCH 43/58] Include list mask in test

---
 pandas/tests/extension/base/getitem.py | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/pandas/tests/extension/base/getitem.py b/pandas/tests/extension/base/getitem.py
index d69efb90388e5..8eae9425b01a1 100644
--- a/pandas/tests/extension/base/getitem.py
+++ b/pandas/tests/extension/base/getitem.py
@@ -158,20 +158,26 @@ def test_getitem_boolean_array_mask(self, data):
         result = pd.Series(data)[mask]
         self.assert_series_equal(result, expected)
 
-    def test_getitem_boolean_na_treated_as_false(self, data):
+    @pytest.mark.parametrize("use_list_mask", [True, False])
+    def test_getitem_boolean_na_treated_as_false(self, data, use_list_mask):
         mask = pd.array(np.zeros(data.shape, dtype="bool"), dtype="boolean")
         mask[:2] = pd.NA
         mask[2:4] = True
+        filled_mask = mask.fillna(False)
+
+        if use_list_mask:
+            mask = list(mask)
+            filled_mask = list(filled_mask)
 
         result = data[mask]
-        expected = data[mask.fillna(False)]
+        expected = data[filled_mask]
 
         self.assert_extension_array_equal(result, expected)
 
         s = pd.Series(data)
 
         result = s[mask]
-        expected = s[mask.fillna(False)]
+        expected = s[filled_mask]
 
         self.assert_series_equal(result, expected)
 

From 705947e238c8db258b9df86581368aa68df5260f Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Mon, 10 Feb 2020 16:07:59 -0600
Subject: [PATCH 44/58] Account for empty key

---
 pandas/core/common.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/pandas/core/common.py b/pandas/core/common.py
index 1892e19dd3681..59127286cc19d 100644
--- a/pandas/core/common.py
+++ b/pandas/core/common.py
@@ -133,7 +133,9 @@ def is_bool_indexer(key: Any) -> bool:
         elif is_bool_dtype(key.dtype):
             return True
     elif isinstance(key, list):
-        return all(k is libmissing.NA or k is True or k is False for k in key)
+        return all(k is libmissing.NA or k is True or k is False for k in key) and (
+            len(key) > 0
+        )
 
     return False
 

From 4974778384444d8ff779a85f9456d63f90301589 Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Mon, 10 Feb 2020 17:00:57 -0600
Subject: [PATCH 45/58] Revert "Account for empty key"

This reverts commit 705947e238c8db258b9df86581368aa68df5260f.
---
 pandas/core/common.py | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/pandas/core/common.py b/pandas/core/common.py
index 59127286cc19d..1892e19dd3681 100644
--- a/pandas/core/common.py
+++ b/pandas/core/common.py
@@ -133,9 +133,7 @@ def is_bool_indexer(key: Any) -> bool:
         elif is_bool_dtype(key.dtype):
             return True
     elif isinstance(key, list):
-        return all(k is libmissing.NA or k is True or k is False for k in key) and (
-            len(key) > 0
-        )
+        return all(k is libmissing.NA or k is True or k is False for k in key)
 
     return False
 

From 319b52549825ea4aa7f268a505d12089f311c91d Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Mon, 10 Feb 2020 17:01:21 -0600
Subject: [PATCH 46/58] Revert "Account for pd.NA in is_bool_indexer"

This reverts commit 578fd3cdf134627013a084e703f6186d019eef75.
---
 pandas/core/common.py | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/pandas/core/common.py b/pandas/core/common.py
index 1892e19dd3681..526a9144ddcbf 100644
--- a/pandas/core/common.py
+++ b/pandas/core/common.py
@@ -13,7 +13,7 @@
 
 import numpy as np
 
-from pandas._libs import lib, tslibs, missing as libmissing
+from pandas._libs import lib, tslibs
 from pandas._typing import T
 
 from pandas.core.dtypes.cast import construct_1d_object_array_from_listlike
@@ -133,7 +133,11 @@ def is_bool_indexer(key: Any) -> bool:
         elif is_bool_dtype(key.dtype):
             return True
     elif isinstance(key, list):
-        return all(k is libmissing.NA or k is True or k is False for k in key)
+        try:
+            arr = np.asarray(key)
+            return arr.dtype == np.bool_ and len(arr) == len(key)
+        except TypeError:  # pragma: no cover
+            return False
 
     return False
 

From 8007ce43a5b609cac8ddf46b5f5cc306f6b70eda Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Tue, 11 Feb 2020 13:24:10 -0600
Subject: [PATCH 47/58] Try modifying is_bool_indexer

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

diff --git a/pandas/core/common.py b/pandas/core/common.py
index 526a9144ddcbf..b6cb97082f18b 100644
--- a/pandas/core/common.py
+++ b/pandas/core/common.py
@@ -27,6 +27,8 @@
 from pandas.core.dtypes.inference import _iterable_not_string
 from pandas.core.dtypes.missing import isna, isnull, notnull  # noqa
 
+import pandas as pd
+
 
 class SettingWithCopyError(ValueError):
     pass
@@ -134,8 +136,8 @@ def is_bool_indexer(key: Any) -> bool:
             return True
     elif isinstance(key, list):
         try:
-            arr = np.asarray(key)
-            return arr.dtype == np.bool_ and len(arr) == len(key)
+            arr = pd.array(key)
+            return is_bool_dtype(arr.dtype) and (len(arr) == len(key))
         except TypeError:  # pragma: no cover
             return False
 

From a10765f217ae3e8e566f230c0093cf00b5e4c8ca Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Tue, 11 Feb 2020 14:37:43 -0600
Subject: [PATCH 48/58] Revert "Try modifying is_bool_indexer"

This reverts commit 8007ce43a5b609cac8ddf46b5f5cc306f6b70eda.
---
 pandas/core/common.py | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/pandas/core/common.py b/pandas/core/common.py
index b6cb97082f18b..526a9144ddcbf 100644
--- a/pandas/core/common.py
+++ b/pandas/core/common.py
@@ -27,8 +27,6 @@
 from pandas.core.dtypes.inference import _iterable_not_string
 from pandas.core.dtypes.missing import isna, isnull, notnull  # noqa
 
-import pandas as pd
-
 
 class SettingWithCopyError(ValueError):
     pass
@@ -136,8 +134,8 @@ def is_bool_indexer(key: Any) -> bool:
             return True
     elif isinstance(key, list):
         try:
-            arr = pd.array(key)
-            return is_bool_dtype(arr.dtype) and (len(arr) == len(key))
+            arr = np.asarray(key)
+            return arr.dtype == np.bool_ and len(arr) == len(key)
         except TypeError:  # pragma: no cover
             return False
 

From d7fc3b7a65e2303e25256966974e377c7d719fc2 Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Tue, 11 Feb 2020 14:38:08 -0600
Subject: [PATCH 49/58] Revert "Include list mask in test"

This reverts commit a5593850b97f09fc72e9411851addcd433290b5c.
---
 pandas/tests/extension/base/getitem.py | 12 +++---------
 1 file changed, 3 insertions(+), 9 deletions(-)

diff --git a/pandas/tests/extension/base/getitem.py b/pandas/tests/extension/base/getitem.py
index 8eae9425b01a1..d69efb90388e5 100644
--- a/pandas/tests/extension/base/getitem.py
+++ b/pandas/tests/extension/base/getitem.py
@@ -158,26 +158,20 @@ def test_getitem_boolean_array_mask(self, data):
         result = pd.Series(data)[mask]
         self.assert_series_equal(result, expected)
 
-    @pytest.mark.parametrize("use_list_mask", [True, False])
-    def test_getitem_boolean_na_treated_as_false(self, data, use_list_mask):
+    def test_getitem_boolean_na_treated_as_false(self, data):
         mask = pd.array(np.zeros(data.shape, dtype="bool"), dtype="boolean")
         mask[:2] = pd.NA
         mask[2:4] = True
-        filled_mask = mask.fillna(False)
-
-        if use_list_mask:
-            mask = list(mask)
-            filled_mask = list(filled_mask)
 
         result = data[mask]
-        expected = data[filled_mask]
+        expected = data[mask.fillna(False)]
 
         self.assert_extension_array_equal(result, expected)
 
         s = pd.Series(data)
 
         result = s[mask]
-        expected = s[filled_mask]
+        expected = s[mask.fillna(False)]
 
         self.assert_series_equal(result, expected)
 

From 6f9a2982179818176c156c2d11296fe8cc3770d0 Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Thu, 13 Feb 2020 08:44:28 -0600
Subject: [PATCH 50/58] Update release notes and docs

---
 doc/source/user_guide/boolean.rst  |  2 ++
 doc/source/user_guide/indexing.rst |  2 ++
 doc/source/whatsnew/v1.0.2.rst     | 27 +++++++++++++++++++++++++++
 doc/source/whatsnew/v1.1.0.rst     | 27 ---------------------------
 4 files changed, 31 insertions(+), 27 deletions(-)

diff --git a/doc/source/user_guide/boolean.rst b/doc/source/user_guide/boolean.rst
index de0130bcd890e..d45bdc08e4a60 100644
--- a/doc/source/user_guide/boolean.rst
+++ b/doc/source/user_guide/boolean.rst
@@ -22,6 +22,8 @@ Indexing with NA values
 
 pandas allows indexing with ``NA`` values in a boolean array, which are treated as ``False``.
 
+.. versionchanged:: 1.0.2
+
 .. ipython:: python
    :okexcept:
 
diff --git a/doc/source/user_guide/indexing.rst b/doc/source/user_guide/indexing.rst
index cc17fcd9e4263..2bd3ff626f2e1 100644
--- a/doc/source/user_guide/indexing.rst
+++ b/doc/source/user_guide/indexing.rst
@@ -376,6 +376,8 @@ For getting values with a boolean array:
 
 NA values in a boolean array propogate as ``False``:
 
+.. versionchanged:: 1.0.2
+
    mask = pd.array([True, False, True, False, pd.NA, False], dtype="boolean")
    mask
    df1[mask]
diff --git a/doc/source/whatsnew/v1.0.2.rst b/doc/source/whatsnew/v1.0.2.rst
index 0216007ea5ba8..3815229dc092c 100644
--- a/doc/source/whatsnew/v1.0.2.rst
+++ b/doc/source/whatsnew/v1.0.2.rst
@@ -46,6 +46,33 @@ Bug fixes
 
 .. ---------------------------------------------------------------------------
 
+Indexing with Nullable Boolean Arrays
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Previously indexing with a nullable Boolean array containing ``NA`` would raise a ``ValueError``, however this is now permitted with ``NA`` being treated as ``False``. (:issue:`31503`)
+
+.. ipython:: python
+
+    s = pd.Series([1, 2, 3, 4])
+    mask = pd.array([True, True, False, None], dtype="boolean")
+    s
+    mask
+
+*pandas 1.0.0-1.0.1*
+
+.. code-block:: python
+
+    >>> s[mask]
+    Traceback (most recent call last):
+    ...
+    ValueError: cannot mask with array containing NA / NaN values
+
+*pandas 1.0.2*
+
+.. ipython:: python
+
+    s[mask]
+
 .. _whatsnew_102.contributors:
 
 Contributors
diff --git a/doc/source/whatsnew/v1.1.0.rst b/doc/source/whatsnew/v1.1.0.rst
index b09edaedef625..13827e8fc4c33 100644
--- a/doc/source/whatsnew/v1.1.0.rst
+++ b/doc/source/whatsnew/v1.1.0.rst
@@ -36,33 +36,6 @@ For example:
    ser["2014"]
    ser.loc["May 2015"]
 
-Indexing with Nullable Boolean Arrays
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-Previously indexing with a nullable Boolean array containing ``NA`` would raise a ``ValueError``, however this is now permitted with ``NA`` being treated as ``False``. (:issue:`31503`)
-
-.. ipython:: python
-
-    s = pd.Series([1, 2, 3, 4])
-    mask = pd.array([True, True, False, None], dtype="boolean")
-    s
-    mask
-
-*pandas 1.0.x*
-
-.. code-block:: python
-
-    >>> s[mask]
-    Traceback (most recent call last):
-    ...
-    ValueError: cannot mask with array containing NA / NaN values
-
-*pandas 1.1.0*
-
-.. ipython:: python
-
-    s[mask]
-
 .. _whatsnew_110.enhancements.other:
 
 Other enhancements

From e1e39fe14d8fd4d5db429579db113022acf44231 Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Thu, 13 Feb 2020 08:55:22 -0600
Subject: [PATCH 51/58] Add issue number to tests

---
 pandas/tests/arrays/categorical/test_indexing.py | 1 +
 pandas/tests/extension/base/getitem.py           | 1 +
 pandas/tests/indexing/test_check_indexer.py      | 1 +
 pandas/tests/indexing/test_na_indexing.py        | 1 +
 4 files changed, 4 insertions(+)

diff --git a/pandas/tests/arrays/categorical/test_indexing.py b/pandas/tests/arrays/categorical/test_indexing.py
index a866eb08f1f4e..3d9469c252914 100644
--- a/pandas/tests/arrays/categorical/test_indexing.py
+++ b/pandas/tests/arrays/categorical/test_indexing.py
@@ -241,6 +241,7 @@ def test_mask_with_boolean(index):
 
 @pytest.mark.parametrize("index", [True, False])
 def test_mask_with_boolean_na_treated_as_false(index):
+    # https://github.com/pandas-dev/pandas/issues/31503
     s = Series(range(3))
     idx = Categorical([True, False, None])
     if index:
diff --git a/pandas/tests/extension/base/getitem.py b/pandas/tests/extension/base/getitem.py
index d69efb90388e5..b08a64cc076b6 100644
--- a/pandas/tests/extension/base/getitem.py
+++ b/pandas/tests/extension/base/getitem.py
@@ -159,6 +159,7 @@ def test_getitem_boolean_array_mask(self, data):
         self.assert_series_equal(result, expected)
 
     def test_getitem_boolean_na_treated_as_false(self, data):
+        # https://github.com/pandas-dev/pandas/issues/31503
         mask = pd.array(np.zeros(data.shape, dtype="bool"), dtype="boolean")
         mask[:2] = pd.NA
         mask[2:4] = True
diff --git a/pandas/tests/indexing/test_check_indexer.py b/pandas/tests/indexing/test_check_indexer.py
index 64f841fdcc41b..69d4065234d93 100644
--- a/pandas/tests/indexing/test_check_indexer.py
+++ b/pandas/tests/indexing/test_check_indexer.py
@@ -35,6 +35,7 @@ def test_valid_input(indexer, expected):
     "indexer", [[True, False, None], pd.array([True, False, None], dtype="boolean")],
 )
 def test_boolean_na_returns_indexer(indexer):
+    # https://github.com/pandas-dev/pandas/issues/31503
     arr = np.array([1, 2, 3])
 
     result = check_array_indexer(arr, indexer)
diff --git a/pandas/tests/indexing/test_na_indexing.py b/pandas/tests/indexing/test_na_indexing.py
index 4a9c93d753cc7..345ca30ec77eb 100644
--- a/pandas/tests/indexing/test_na_indexing.py
+++ b/pandas/tests/indexing/test_na_indexing.py
@@ -63,6 +63,7 @@ def test_series_mask_boolean(values, dtype, mask, box_mask, frame):
 
 @pytest.mark.parametrize("frame", [True, False])
 def test_na_treated_as_false(frame):
+    # https://github.com/pandas-dev/pandas/issues/31503
     s = pd.Series([1, 2, 3], name="name")
 
     if frame:

From 5a72b2f9e9c99b133a6173e695c77da759fedd74 Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Thu, 13 Feb 2020 09:36:59 -0600
Subject: [PATCH 52/58] Add some setitem tests

---
 pandas/tests/extension/base/setitem.py | 30 ++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/pandas/tests/extension/base/setitem.py b/pandas/tests/extension/base/setitem.py
index 590bcd586900a..79b0a37c06f5f 100644
--- a/pandas/tests/extension/base/setitem.py
+++ b/pandas/tests/extension/base/setitem.py
@@ -133,6 +133,36 @@ def test_setitem_mask_broadcast(self, data, setter):
         assert ser[0] == data[10]
         assert ser[1] == data[10]
 
+    def test_setitem_boolean_na_mask(self, data, box_in_series):
+        # https://github.com/pandas-dev/pandas/issues/31503
+        if box_in_series:
+            data = pd.Series(data)
+
+        mask = pd.array(np.zeros(len(data), dtype=bool), dtype="boolean")
+        mask[:2] = pd.NA
+        mask[2:4] = True
+        original = data.copy()
+
+        data[mask] = data[mask.fillna(False)]
+
+        if box_in_series:
+            tm.assert_series_equal(data, original)
+        else:
+            tm.assert_extension_array_equal(data, original)
+
+    def test_setitem_boolean_na_mask_frame(self, data):
+        # https://github.com/pandas-dev/pandas/issues/31503
+        df = pd.DataFrame({"a": range(len(data)), "b": data})
+        original = df.copy()
+
+        mask = pd.array(np.zeros(len(data), dtype=bool), dtype="boolean")
+        mask[:2] = pd.NA
+        mask[2:4] = True
+
+        df.loc[mask, "b"] = data[mask.fillna(False)]
+
+        tm.assert_frame_equal(df, original)
+
     def test_setitem_expand_columns(self, data):
         df = pd.DataFrame({"A": data})
         result = df.copy()

From c0e8dc72e2e78f1d4290ab60c583bc4b034c20f7 Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Thu, 13 Feb 2020 10:35:29 -0600
Subject: [PATCH 53/58] Revert "Add some setitem tests"

This reverts commit 5a72b2f9e9c99b133a6173e695c77da759fedd74.
---
 pandas/tests/extension/base/setitem.py | 30 --------------------------
 1 file changed, 30 deletions(-)

diff --git a/pandas/tests/extension/base/setitem.py b/pandas/tests/extension/base/setitem.py
index 79b0a37c06f5f..590bcd586900a 100644
--- a/pandas/tests/extension/base/setitem.py
+++ b/pandas/tests/extension/base/setitem.py
@@ -133,36 +133,6 @@ def test_setitem_mask_broadcast(self, data, setter):
         assert ser[0] == data[10]
         assert ser[1] == data[10]
 
-    def test_setitem_boolean_na_mask(self, data, box_in_series):
-        # https://github.com/pandas-dev/pandas/issues/31503
-        if box_in_series:
-            data = pd.Series(data)
-
-        mask = pd.array(np.zeros(len(data), dtype=bool), dtype="boolean")
-        mask[:2] = pd.NA
-        mask[2:4] = True
-        original = data.copy()
-
-        data[mask] = data[mask.fillna(False)]
-
-        if box_in_series:
-            tm.assert_series_equal(data, original)
-        else:
-            tm.assert_extension_array_equal(data, original)
-
-    def test_setitem_boolean_na_mask_frame(self, data):
-        # https://github.com/pandas-dev/pandas/issues/31503
-        df = pd.DataFrame({"a": range(len(data)), "b": data})
-        original = df.copy()
-
-        mask = pd.array(np.zeros(len(data), dtype=bool), dtype="boolean")
-        mask[:2] = pd.NA
-        mask[2:4] = True
-
-        df.loc[mask, "b"] = data[mask.fillna(False)]
-
-        tm.assert_frame_equal(df, original)
-
     def test_setitem_expand_columns(self, data):
         df = pd.DataFrame({"A": data})
         result = df.copy()

From 607d9ed7e8c41b0607f87092d04f8506c97a3ea2 Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Thu, 13 Feb 2020 11:09:04 -0600
Subject: [PATCH 54/58] Update setitem tests

---
 pandas/tests/extension/base/setitem.py | 18 ++----------------
 pandas/tests/extension/test_numpy.py   |  4 ----
 2 files changed, 2 insertions(+), 20 deletions(-)

diff --git a/pandas/tests/extension/base/setitem.py b/pandas/tests/extension/base/setitem.py
index af70799c0236e..b7bb9fd7d5a08 100644
--- a/pandas/tests/extension/base/setitem.py
+++ b/pandas/tests/extension/base/setitem.py
@@ -98,8 +98,9 @@ def test_setitem_iloc_scalar_multiple_homogoneous(self, data):
         [
             np.array([True, True, True, False, False]),
             pd.array([True, True, True, False, False], dtype="boolean"),
+            pd.array([True, True, True, pd.NA, pd.NA], dtype="boolean"),
         ],
-        ids=["numpy-array", "boolean-array"],
+        ids=["numpy-array", "boolean-array", "boolean-array-na"],
     )
     def test_setitem_mask(self, data, mask, box_in_series):
         arr = data[:5].copy()
@@ -124,21 +125,6 @@ def test_setitem_mask_raises(self, data, box_in_series):
         with pytest.raises(IndexError, match="wrong length"):
             data[mask] = data[0]
 
-    def test_setitem_mask_boolean_array_raises(self, data, box_in_series):
-        # missing values in mask
-        mask = pd.array(np.zeros(data.shape, dtype="bool"), dtype="boolean")
-        mask[:2] = pd.NA
-
-        if box_in_series:
-            data = pd.Series(data)
-
-        msg = (
-            "Cannot mask with a boolean indexer containing NA values|"
-            "cannot mask with array containing NA / NaN values"
-        )
-        with pytest.raises(ValueError, match=msg):
-            data[mask] = data[0]
-
     @pytest.mark.parametrize(
         "idx",
         [[0, 1, 2], pd.array([0, 1, 2], dtype="Int64"), np.array([0, 1, 2])],
diff --git a/pandas/tests/extension/test_numpy.py b/pandas/tests/extension/test_numpy.py
index 80a093530a8cd..61c5925383f88 100644
--- a/pandas/tests/extension/test_numpy.py
+++ b/pandas/tests/extension/test_numpy.py
@@ -415,10 +415,6 @@ def test_setitem_mask(self, data, mask, box_in_series):
     def test_setitem_mask_raises(self, data, box_in_series):
         super().test_setitem_mask_raises(data, box_in_series)
 
-    @skip_nested
-    def test_setitem_mask_boolean_array_raises(self, data, box_in_series):
-        super().test_setitem_mask_boolean_array_raises(data, box_in_series)
-
     @skip_nested
     @pytest.mark.parametrize(
         "idx",

From c6d23f68f1d732a1657f07ccd37ceb877ca61706 Mon Sep 17 00:00:00 2001
From: Daniel Saxton <danielsaxton@DANIELs-MacBook-Pro.local>
Date: Mon, 17 Feb 2020 11:55:35 -0600
Subject: [PATCH 55/58] Add setitem test

---
 pandas/tests/extension/base/setitem.py | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/pandas/tests/extension/base/setitem.py b/pandas/tests/extension/base/setitem.py
index b7bb9fd7d5a08..a4fe89df158fa 100644
--- a/pandas/tests/extension/base/setitem.py
+++ b/pandas/tests/extension/base/setitem.py
@@ -125,6 +125,18 @@ def test_setitem_mask_raises(self, data, box_in_series):
         with pytest.raises(IndexError, match="wrong length"):
             data[mask] = data[0]
 
+    def test_setitem_mask_boolean_array_with_na(self, data, box_in_series):
+        mask = pd.array(np.zeros(data.shape, dtype="bool"), dtype="boolean")
+        mask[:3] = True
+        mask[3:5] = pd.NA
+
+        if box_in_series:
+            data = pd.Series(data)
+
+        data[mask] = data[0]
+
+        assert (data[:3] == data[0]).all()
+
     @pytest.mark.parametrize(
         "idx",
         [[0, 1, 2], pd.array([0, 1, 2], dtype="Int64"), np.array([0, 1, 2])],

From fbda99d30496e9e3a2c037b24bf475ea046f2ecf Mon Sep 17 00:00:00 2001
From: Daniel Saxton <dsaxton@pm.me>
Date: Wed, 19 Feb 2020 09:04:53 -0600
Subject: [PATCH 56/58] Move whatsnew note

---
 doc/source/whatsnew/v1.0.2.rst | 48 ++++++++++++++++------------------
 1 file changed, 23 insertions(+), 25 deletions(-)

diff --git a/doc/source/whatsnew/v1.0.2.rst b/doc/source/whatsnew/v1.0.2.rst
index 093c8df1ba788..25fc9a4590fce 100644
--- a/doc/source/whatsnew/v1.0.2.rst
+++ b/doc/source/whatsnew/v1.0.2.rst
@@ -23,32 +23,8 @@ Fixed regressions
 
 .. ---------------------------------------------------------------------------
 
-.. _whatsnew_102.bug_fixes:
-
-Bug fixes
-~~~~~~~~~
-
-**Categorical**
-
-- Fixed bug where :meth:`Categorical.from_codes` improperly raised a ``ValueError`` when passed nullable integer codes. (:issue:`31779`)
-- Bug in :class:`Categorical` that would ignore or crash when calling :meth:`Series.replace` with a list-like ``to_replace`` (:issue:`31720`)
-
-**I/O**
-
-- Using ``pd.NA`` with :meth:`DataFrame.to_json` now correctly outputs a null value instead of an empty object (:issue:`31615`)
-- Fixed bug in parquet roundtrip with nullable unsigned integer dtypes (:issue:`31896`).
-
-
-
-**Experimental dtypes**
-
-- Fix bug in :meth:`DataFrame.convert_dtypes` for columns that were already using the ``"string"`` dtype (:issue:`31731`).
-- Fixed bug in setting values using a slice indexer with string dtype (:issue:`31772`)
-
-.. ---------------------------------------------------------------------------
-
 Indexing with Nullable Boolean Arrays
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 Previously indexing with a nullable Boolean array containing ``NA`` would raise a ``ValueError``, however this is now permitted with ``NA`` being treated as ``False``. (:issue:`31503`)
 
@@ -74,6 +50,28 @@ Previously indexing with a nullable Boolean array containing ``NA`` would raise
 
     s[mask]
 
+.. _whatsnew_102.bug_fixes:
+
+Bug fixes
+~~~~~~~~~
+
+**Categorical**
+
+- Fixed bug where :meth:`Categorical.from_codes` improperly raised a ``ValueError`` when passed nullable integer codes. (:issue:`31779`)
+- Bug in :class:`Categorical` that would ignore or crash when calling :meth:`Series.replace` with a list-like ``to_replace`` (:issue:`31720`)
+
+**I/O**
+
+- Using ``pd.NA`` with :meth:`DataFrame.to_json` now correctly outputs a null value instead of an empty object (:issue:`31615`)
+- Fixed bug in parquet roundtrip with nullable unsigned integer dtypes (:issue:`31896`).
+
+**Experimental dtypes**
+
+- Fix bug in :meth:`DataFrame.convert_dtypes` for columns that were already using the ``"string"`` dtype (:issue:`31731`).
+- Fixed bug in setting values using a slice indexer with string dtype (:issue:`31772`)
+
+.. ---------------------------------------------------------------------------
+
 .. _whatsnew_102.contributors:
 
 Contributors

From 3bf932740a25ad51f825912a7c076418394a3183 Mon Sep 17 00:00:00 2001
From: Daniel Saxton <dsaxton@pm.me>
Date: Wed, 19 Feb 2020 09:09:11 -0600
Subject: [PATCH 57/58] Add back example

---
 doc/source/user_guide/boolean.rst | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/doc/source/user_guide/boolean.rst b/doc/source/user_guide/boolean.rst
index d45bdc08e4a60..6370a523b9a0d 100644
--- a/doc/source/user_guide/boolean.rst
+++ b/doc/source/user_guide/boolean.rst
@@ -31,6 +31,12 @@ pandas allows indexing with ``NA`` values in a boolean array, which are treated
    mask = pd.array([True, False, pd.NA], dtype="boolean")
    s[mask]
 
+If you would prefer to keep the ``NA`` values you can manually fill them with ``fillna(True)``.
+
+.. ipython:: python
+
+   s[mask.fillna(True)]
+
 .. _boolean.kleene:
 
 Kleene Logical Operations

From 080d1d2129f101460af12b23d6f2b400e1a66e61 Mon Sep 17 00:00:00 2001
From: Daniel Saxton <dsaxton@pm.me>
Date: Fri, 21 Feb 2020 13:44:06 -0600
Subject: [PATCH 58/58] Update comment

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

diff --git a/pandas/core/indexing.py b/pandas/core/indexing.py
index ab909a5792f66..5ae237eb7dc32 100755
--- a/pandas/core/indexing.py
+++ b/pandas/core/indexing.py
@@ -2191,7 +2191,7 @@ def check_bool_indexer(index: Index, key) -> np.ndarray:
             )
         result = result.astype(bool)._values
     elif is_object_dtype(key):
-        # key might be sparse / object-dtype bool, check_array_indexer needs bool array
+        # key might be object-dtype bool, check_array_indexer needs bool array
         result = np.asarray(result, dtype=bool)
         result = check_array_indexer(index, result)
     else: