FIX: Closes pandas-dev#7879: (drops not nan in panel.to_frame() by default)

Author: hensing

pandas/core/panel.py

@@ -862,15 +862,16 @@ def groupby(self, function, axis='major'):
         axis = self._get_axis_number(axis)
         return PanelGroupBy(self, function, axis=axis)
 
-    def to_frame(self, filter_observations=True):
+    @deprecate_kwarg(old_arg_name='filter_observations', new_arg_name='dropna')
+    def to_frame(self, dropna=False):
         """
         Transform wide format into long (stacked) format as DataFrame whose
         columns are the Panel's items and whose index is a MultiIndex formed
         of the Panel's major and minor axes.
 
         Parameters
         ----------
-        filter_observations : boolean, default True
+        dropna : boolean, default False
             Drop (major, minor) pairs without a complete set of observations
             across all the items
 
@@ -880,7 +881,7 @@ def to_frame(self, filter_observations=True):
         """
         _, N, K = self.shape
 
-        if filter_observations:
+        if dropna is True:
             # shaped like the return DataFrame
             mask = com.notnull(self.values).all(axis=0)
             # size = mask.sum()

pandas/tests/test_panel.py

@@ -1507,19 +1507,19 @@ def test_transpose_copy(self):
 
     def test_to_frame(self):
         # filtered
-        filtered = self.panel.to_frame()
+        filtered = self.panel.to_frame(dropna=True)
         expected = self.panel.to_frame().dropna(how='any')
         assert_frame_equal(filtered, expected)
 
         # unfiltered
-        unfiltered = self.panel.to_frame(filter_observations=False)
+        unfiltered = self.panel.to_frame(dropna=False)
         assert_panel_equal(unfiltered.to_panel(), self.panel)
 
         # names
         self.assertEqual(unfiltered.index.names, ('major', 'minor'))
 
         # unsorted, round trip
-        df = self.panel.to_frame(filter_observations=False)
+        df = self.panel.to_frame(dropna=False)
         unsorted = df.take(np.random.permutation(len(df)))
         pan = unsorted.to_panel()
         assert_panel_equal(pan, self.panel)
@@ -2192,7 +2192,7 @@ def setUp(self):
         tm.add_nans(panel)
 
         self.panel = panel.to_frame()
-        self.unfiltered_panel = panel.to_frame(filter_observations=False)
+        self.unfiltered_panel = panel.to_frame(dropna=False)
 
     def test_ops_differently_indexed(self):
         # trying to set non-identically indexed panel