Merge pull request pandas-dev#6824 from jreback/fillna

BUG: Regression from 0.13 with fillna and a Series on datetime-like (6344)

Author: jreback

doc/source/release.rst

@@ -321,6 +321,7 @@ Bug Fixes
 - Bug with numpy < 1.7.2 when reading long strings from ``HDFStore`` (:issue:`6166`)
 - Bug in ``DataFrame._reduce`` where non bool-like (0/1) integers were being
   coverted into bools. (:issue:`6806`)
+- Regression from 0.13 with ``fillna`` and a Series on datetime-like (:issue:`6344`)
 
 pandas 0.13.1
 -------------

pandas/core/internals.py

@@ -374,7 +374,7 @@ def fillna(self, value, limit=None, inplace=False, downcast=None):
             else:
                 return [self.copy()]
 
-        mask = com.isnull(self.values)
+        mask = isnull(self.values)
         if limit is not None:
             if self.ndim > 2:
                 raise NotImplementedError
@@ -1306,7 +1306,7 @@ def fill_value(self):
 
     def _try_fill(self, value):
         """ if we are a NaT, return the actual fill value """
-        if isinstance(value, type(tslib.NaT)) or isnull(value):
+        if isinstance(value, type(tslib.NaT)) or np.array(isnull(value)).all():
             value = tslib.iNaT
         elif isinstance(value, np.timedelta64):
             pass
@@ -1688,7 +1688,7 @@ def fill_value(self):
 
     def _try_fill(self, value):
         """ if we are a NaT, return the actual fill value """
-        if isinstance(value, type(tslib.NaT)) or isnull(value):
+        if isinstance(value, type(tslib.NaT)) or np.array(isnull(value)).all():
             value = tslib.iNaT
         return value
 
@@ -1697,7 +1697,7 @@ def fillna(self, value, limit=None,
 
         # straight putmask here
         values = self.values if inplace else self.values.copy()
-        mask = com.isnull(self.values)
+        mask = isnull(self.values)
         value = self._try_fill(value)
         if limit is not None:
             if self.ndim > 2:

pandas/tests/test_frame.py

@@ -7221,6 +7221,18 @@ def test_fillna(self):
         result = df.fillna(999,limit=1)
         assert_frame_equal(result, expected)
 
+        # with datelike
+        # GH 6344
+        df = DataFrame({
+            'Date':[pd.NaT, Timestamp("2014-1-1")],
+            'Date2':[ Timestamp("2013-1-1"), pd.NaT]
+            })
+
+        expected = df.copy()
+        expected['Date'] = expected['Date'].fillna(df.ix[0,'Date2'])
+        result = df.fillna(value={'Date':df['Date2']})
+        assert_frame_equal(result, expected)
+
     def test_fillna_dtype_conversion(self):
         # make sure that fillna on an empty frame works
         df = DataFrame(index=["A","B","C"], columns = [1,2,3,4,5])