BUG: Possibly invalidate the item_cache when numpy implicty converts a v...

doc/source/release.rst

@@ -287,7 +287,7 @@ pandas 0.12
   - Fixed insertion issue into DataFrame, after rename (:issue:`4032`)
   - Fixed testing issue where too many sockets where open thus leading to a
     connection reset issue (:issue:`3982`, :issue:`3985`)
-
+  - Possibly invalidate the item_cache when numpy implicty converts a view to a copy (:issue:`3970`)
 
 pandas 0.11.0
 =============

pandas/core/generic.py

@@ -1,5 +1,6 @@
 # pylint: disable=W0231,E1101
 
+import weakref
 import numpy as np
 
 from pandas.core.index import MultiIndex
@@ -666,6 +667,7 @@ def _get_item_cache(self, item):
             values = self._data.get(item)
             res = self._box_item_values(item, values)
             cache[item] = res
+            res._cacher = weakref.ref(self)
             return res
 
     def _box_item_values(self, key, values):
@@ -1065,6 +1067,7 @@ def take(self, indices, axis=0, convert=True):
             new_data = self._data.reindex_axis(new_items, axis=0)
         else:
             new_data = self._data.take(indices, axis=axis, verify=False)
+
         return self._constructor(new_data)
 
     def tz_convert(self, tz, axis=0, copy=True):

pandas/core/indexing.py

@@ -184,6 +184,14 @@ def setter(item, v):
             if np.prod(values.shape):
                 values[indexer] = value
 
+            # we might need to invalidate a cached version of myself
+            cacher = getattr(self.obj,'_cacher',None)
+            if cacher is not None:
+                try:
+                    cacher()._clear_item_cache()
+                except:
+                    pass
+
     def _align_series(self, indexer, ser):
         # indexer to assign Series can be tuple or scalar
         if isinstance(indexer, tuple):
@@ -709,6 +717,7 @@ def _getbool_axis(self, key, axis=0):
                 return self.obj.take(inds, axis=axis, convert=False)
             except (Exception), detail:
                 raise self._exception(detail)
+
     def _get_slice_axis(self, slice_obj, axis=0):
         """ this is pretty simple as we just have to deal with labels """
         obj = self.obj

pandas/core/internals.py

@@ -1650,6 +1650,7 @@ def _consolidate_inplace(self):
             self._known_consolidated = True
 
     def get(self, item):
+
         if self.items.is_unique:
             _, block = self._find_block(item)
             return block.get(item)

pandas/tests/test_indexing.py

@@ -1066,7 +1066,18 @@ def test_iloc_non_unique_indexing(self):
         result = df2.loc[idx]
         assert_frame_equal(result, expected)
 
-
+    def test_series_iloc(self):
+        # GH 3970
+
+        df = DataFrame({ "aa":range(5), "bb":[2.2]*5})
+        df["cc"] = 0.0
+        ck = [True]*len(df)
+        df["bb"].loc[0] = .13 # works
+        df_tmp = df.iloc[ck]
+        df["bb"].loc[0] = .15 # doesn't work
+        expected = DataFrame({ "aa":range(5), "bb":[0.15,2.2,2.2,2.2,2.2], "cc": 0.0 })
+        assert_frame_equal(df, expected)
+
 if __name__ == '__main__':
     import nose
     nose.runmodule(argv=[__file__, '-vvs', '-x', '--pdb', '--pdb-failure'],