BUG: consistency between logical ops & type casts

doc/source/v0.15.0.txt

@@ -650,4 +650,4 @@ Bug Fixes
 - Bug in accessing groups from a ``GroupBy`` when the original grouper
   was a tuple (:issue:`8121`).
 
-
+- Bug in logical operations of series and their consistency with type casts (:issue:`6528`)

pandas/core/ops.py

@@ -636,10 +636,12 @@ def wrapper(self, other):
         if isinstance(other, pd.Series):
             name = _maybe_match_name(self, other)
 
-            other = other.reindex_like(self).fillna(False).astype(bool)
-            return self._constructor(na_op(self.values, other.values),
+            left  = self.astype(bool).values
+            right = other.astype(bool).reindex_like(self)
+            right = right.fillna(False).values
+            return self._constructor(na_op(left, right),
                                      index=self.index,
-                                     name=name).fillna(False).astype(bool)
+                                     name=name)
         elif isinstance(other, pd.DataFrame):
             return NotImplemented
         else:

pandas/tests/test_frame.py

@@ -4992,7 +4992,7 @@ def test_logical_with_nas(self):
         # GH4947
         # bool comparisons should return bool
         result = d['a'] | d['b']
-        expected = Series([False, True])
+        expected = Series(np.logical_or(d['a'], d['b']), dtype='bool')
         assert_series_equal(result, expected)
 
         # GH4604, automatic casting here

pandas/tests/test_series.py

@@ -2368,6 +2368,31 @@ def check(series, other, check_reverse=False):
         check(self.ts, 5, check_reverse=True)
         check(tm.makeFloatSeries(), tm.makeFloatSeries(), check_reverse=True)
 
+    def test_bool_op(self): # GH6528 & GH8151
+        u = pd.Series([nan, nan,   nan,  False, False, True,  True])
+        v = pd.Series([nan, False, True, False, True,  False, True])
+
+        for a, b in [[u, v], [v, u]]:
+            # against numpy logical casted to bool
+            assert_series_equal(a | b, Series(np.logical_or(a, b), dtype='bool'))
+            assert_series_equal(a & b, Series(np.logical_and(a, b), dtype='bool'))
+            assert_series_equal(a ^ b, # np.logical_xor throws with floats!
+                    Series(np.logical_xor(a.values.astype(bool),
+                                          b.values.astype(bool))))
+
+            assert_series_equal(~ a.astype(bool),
+                    Series(np.logical_not(a), dtype='bool'))
+
+            # type cast semantics
+            assert_series_equal(a | b, a.astype(bool) | b.astype(bool))
+            assert_series_equal(a & b, a.astype(bool) & b.astype(bool))
+            assert_series_equal(a ^ b, a.astype(bool) ^ b.astype(bool))
+
+            # symmetry
+            assert_series_equal(a & b, b & a)
+            assert_series_equal(a | b, b | a)
+            assert_series_equal(a ^ b, b ^ a)
+
     def test_neg(self):
         assert_series_equal(-self.series, -1 * self.series)
 
@@ -3418,7 +3443,7 @@ def test_comparison_label_based(self):
 
         # identity
         # we would like s[s|e] == s to hold for any e, whether empty or not
-        for e in [Series([]),Series([1],['z']),Series(['z']),Series(np.nan,b.index),Series(np.nan,a.index)]:
+        for e in [Series([]),Series([1],['z']),Series(['z']),Series(False,b.index),Series(False,a.index)]:
             result = a[a | e]
             assert_series_equal(result,a[a])
 
@@ -6144,4 +6169,3 @@ def test_unique_data_ownership(self):
 if __name__ == '__main__':
     nose.runmodule(argv=[__file__, '-vvs', '-x', '--pdb', '--pdb-failure'],
                    exit=False)
-