BUG: PEBKAC bug in Float64Index

Author: cpcloud

doc/source/release.rst

@@ -475,6 +475,8 @@ Bug Fixes
   caused possible color/class mismatch (:issue:`6956`)
 - Bug in ``radviz`` and ``andrews_curves`` where multiple values of 'color'
   were being passed to plotting method (:issue:`6956`)
+- Bug in ``Float64Index.isin()`` where containing ``nan`` s would make indices
+  claim that they contained all the things (:issue:`7066`).
 
 pandas 0.13.1
 -------------

pandas/core/index.py

@@ -2096,7 +2096,8 @@ def isin(self, values):
         """
         value_set = set(values)
         return lib.ismember_nans(self._array_values(), value_set,
-                                 self._hasnans)
+                                 isnull(list(value_set)).any())
+
 
 class MultiIndex(Index):
 

pandas/tests/test_index.py

@@ -913,6 +913,12 @@ def test_contains_not_nans(self):
         i = Float64Index([1.0, 2.0, np.nan])
         self.assertTrue(1.0 in i)
 
+    def test_doesnt_contain_all_the_things(self):
+        i = Float64Index([np.nan])
+        self.assertFalse(i.isin([0]).item())
+        self.assertFalse(i.isin([1]).item())
+        self.assertTrue(i.isin([np.nan]).item())
+
 
 class TestInt64Index(tm.TestCase):
     _multiprocess_can_split_ = True