Backport PR #21921: BUG:Clip with a list-like threshold with a nan is…

… broken (GH19992)
pandas-dev · Jul 18, 2018 · 5c83562 · 5c83562
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Showing 4 changed files with 28 additions and 8 deletions.
diff --git a/doc/source/whatsnew/v0.23.4.txt b/doc/source/whatsnew/v0.23.4.txt
@@ -58,3 +58,7 @@ Bug Fixes
 
 -
 -
+
+**Missing**
+
+- Bug in :func:`Series.clip` and :func:`DataFrame.clip` cannot accept list-like threshold containing ``NaN`` (:issue:`19992`)
diff --git a/pandas/core/generic.py b/pandas/core/generic.py
@@ -6433,9 +6433,11 @@ def clip(self, lower=None, upper=None, axis=None, inplace=False,
         # GH 17276
         # numpy doesn't like NaN as a clip value
         # so ignore
-        if np.any(pd.isnull(lower)):
+        # GH 19992
+        # numpy doesn't drop a list-like bound containing NaN
+        if not is_list_like(lower) and np.any(pd.isnull(lower)):
             lower = None
-        if np.any(pd.isnull(upper)):
+        if not is_list_like(upper) and np.any(pd.isnull(upper)):
             upper = None
 
         # GH 2747 (arguments were reversed)

diff --git a/pandas/tests/frame/test_analytics.py b/pandas/tests/frame/test_analytics.py
@@ -2195,13 +2195,23 @@ def test_clip_with_na_args(self):
         """Should process np.nan argument as None """
         # GH # 17276
         tm.assert_frame_equal(self.frame.clip(np.nan), self.frame)
-        tm.assert_frame_equal(self.frame.clip(upper=[1, 2, np.nan]),
-                              self.frame)
-        tm.assert_frame_equal(self.frame.clip(lower=[1, np.nan, 3]),
-                              self.frame)
         tm.assert_frame_equal(self.frame.clip(upper=np.nan, lower=np.nan),
                               self.frame)
 
+        # GH #19992
+        df = DataFrame({'col_0': [1, 2, 3], 'col_1': [4, 5, 6],
+                        'col_2': [7, 8, 9]})
+
+        result = df.clip(lower=[4, 5, np.nan], axis=0)
+        expected = DataFrame({'col_0': [4, 5, np.nan], 'col_1': [4, 5, np.nan],
+                              'col_2': [7, 8, np.nan]})
+        tm.assert_frame_equal(result, expected)
+
+        result = df.clip(lower=[4, 5, np.nan], axis=1)
+        expected = DataFrame({'col_0': [4, 4, 4], 'col_1': [5, 5, 6],
+                              'col_2': [np.nan, np.nan, np.nan]})
+        tm.assert_frame_equal(result, expected)
+
     # Matrix-like
     def test_dot(self):
         a = DataFrame(np.random.randn(3, 4), index=['a', 'b', 'c'],

diff --git a/pandas/tests/series/test_analytics.py b/pandas/tests/series/test_analytics.py
@@ -1140,11 +1140,15 @@ def test_clip_with_na_args(self):
         s = Series([1, 2, 3])
 
         assert_series_equal(s.clip(np.nan), Series([1, 2, 3]))
-        assert_series_equal(s.clip(upper=[1, 1, np.nan]), Series([1, 2, 3]))
-        assert_series_equal(s.clip(lower=[1, np.nan, 1]), Series([1, 2, 3]))
         assert_series_equal(s.clip(upper=np.nan, lower=np.nan),
                             Series([1, 2, 3]))
 
+        # GH #19992
+        assert_series_equal(s.clip(lower=[0, 4, np.nan]),
+                            Series([1, 4, np.nan]))
+        assert_series_equal(s.clip(upper=[1, np.nan, 1]),
+                            Series([1, np.nan, 1]))
+
     def test_clip_against_series(self):
         # GH #6966