Issue #806 DataFrame/Series.align can now specify fill_value or fill_method

pandas/core/frame.py

@@ -1669,7 +1669,8 @@ def lookup(self, row_labels, col_labels):
     #----------------------------------------------------------------------
     # Reindexing and alignment
 
-    def align(self, other, join='outer', axis=None, level=None, copy=True):
+    def align(self, other, join='outer', axis=None, level=None, copy=True,
+              fill_value=None, fill_method=None):
         """
         Align two DataFrame object on their index and columns with the
         specified join method for each axis Index
@@ -1683,6 +1684,11 @@ def align(self, other, join='outer', axis=None, level=None, copy=True):
         level : int or name
             Broadcast across a level, matching Index values on the
             passed MultiIndex level
+        copy : boolean, default True
+            Always returns new objects. If copy=False and no reindexing is
+            required then original objects are returned.
+        fill_value : object, default None
+        fill_method : str, default None
 
         Returns
         -------
@@ -1691,15 +1697,19 @@ def align(self, other, join='outer', axis=None, level=None, copy=True):
         """
         if isinstance(other, DataFrame):
             return self._align_frame(other, join=join, axis=axis, level=level,
-                                     copy=copy)
+                                     copy=copy, 
+                                     fill_value=fill_value,
+                                     fill_method=fill_method)
         elif isinstance(other, Series):
             return self._align_series(other, join=join, axis=axis, level=level,
-                                      copy=copy)
+                                      copy=copy, 
+                                      fill_value=fill_value,
+                                      fill_method=fill_method)
         else:  # pragma: no cover
             raise TypeError('unsupported type: %s' % type(other))
 
     def _align_frame(self, other, join='outer', axis=None, level=None,
-                     copy=True):
+                     copy=True, fill_value=None, fill_method=None):
         # defaults
         join_index, join_columns = None, None
         ilidx, iridx = None, None
@@ -1721,10 +1731,15 @@ def _align_frame(self, other, join='outer', axis=None, level=None,
                                            join_columns, clidx, copy)
         right = other._reindex_with_indexers(join_index, iridx,
                                              join_columns, cridx, copy)
-        return left, right
+        fill_na = (fill_value is not None) or (fill_method is not None)
+        if fill_na:
+            return (left.fillna(fill_value, method=fill_method),
+                    right.fillna(fill_value, method=fill_method))
+        else:
+            return left, right
 
     def _align_series(self, other, join='outer', axis=None, level=None,
-                      copy=True):
+                      copy=True, fill_value=None, fill_method=None):
         fdata = self._data
         if axis == 0:
             join_index = self.index
@@ -1753,7 +1768,13 @@ def _align_series(self, other, join='outer', axis=None, level=None,
 
         left_result = DataFrame(fdata)
         right_result = other if ridx is None else other.reindex(join_index)
-        return left_result, right_result
+
+        fill_na = (fill_value is not None) or (fill_method is not None)
+        if fill_na:
+            return (left_result.fillna(fill_value, fill_method=fill_method),
+                    right_result.fillna(fill_value, fill_method=fill_method))
+        else:
+            return left_result, right_result
 
     def reindex(self, index=None, columns=None, method=None, level=None,
                 copy=True):
@@ -4080,18 +4101,6 @@ def _to_sdict(data, columns):
     else:  # pragma: no cover
         raise TypeError('No logic to handle %s type' % type(data[0]))
 
-def _list_to_sdict(data, columns):
-    if len(data) > 0 and isinstance(data[0], tuple):
-        content = list(lib.to_object_array_tuples(data).T)
-    elif len(data) > 0:
-        # list of lists
-        content = list(lib.to_object_array(data).T)
-    else:
-        if columns is None:
-            columns = []
-        return {}, columns
-    return _convert_object_array(content, columns)
-
 def _list_of_series_to_sdict(data, columns):
     from pandas.core.index import _get_combined_index
 
@@ -4107,6 +4116,7 @@ def _list_of_series_to_sdict(data, columns):
     else:
         return values, columns
 
+
 def _list_of_dict_to_sdict(data, columns):
     if columns is None:
         gen = (x.keys() for x in data)

pandas/core/series.py

@@ -1786,7 +1786,8 @@ def apply(self, func):
             mapped = lib.map_infer(self.values, func)
             return Series(mapped, index=self.index, name=self.name)
 
-    def align(self, other, join='outer', level=None, copy=True):
+    def align(self, other, join='outer', level=None, copy=True,
+              fill_value=None, fill_method=None):
         """
         Align two Series object with the specified join method
 
@@ -1800,6 +1801,8 @@ def align(self, other, join='outer', level=None, copy=True):
         copy : boolean, default True
             Always return new objects. If copy=False and no reindexing is
             required, the same object will be returned (for better performance)
+        fill_value : object, default None
+        fill_method : str, default 'pad'
 
         Returns
         -------
@@ -1812,7 +1815,12 @@ def align(self, other, join='outer', level=None, copy=True):
 
         left = self._reindex_indexer(join_index, lidx, copy)
         right = other._reindex_indexer(join_index, ridx, copy)
-        return left, right
+        fill_na = (fill_value is not None) or (fill_method is not None)
+        if fill_na:
+            return (left.fillna(fill_value, method=fill_method),
+                    right.fillna(fill_value, method=fill_method))
+        else:
+            return left, right
 
     def _reindex_indexer(self, new_index, indexer, copy):
         if indexer is not None:

pandas/tests/test_frame.py

@@ -3180,8 +3180,15 @@ def test_align(self):
 
         # axis = 0
         other = self.frame.ix[:-5, :3]
-        af, bf = self.frame.align(other, axis=0)
-        self.assert_(bf.columns.equals(other.columns))
+        af, bf = self.frame.align(other, axis=0, fill_value=-1)
+        self.assert_(bf.columns.equals(other.columns))        
+        #test fill value
+        join_idx = self.frame.index.join(other.index)
+        diff_a = self.frame.index.diff(join_idx)
+        diff_b = other.index.diff(join_idx)
+        diff_a_vals = af.reindex(diff_a).values
+        diff_b_vals = bf.reindex(diff_b).values
+        self.assert_((diff_a_vals == -1).all())
 
         af, bf = self.frame.align(other, join='right', axis=0)
         self.assert_(bf.columns.equals(other.columns))
@@ -3194,6 +3201,14 @@ def test_align(self):
         self.assert_(bf.columns.equals(self.frame.columns))
         self.assert_(bf.index.equals(other.index))
 
+        #test fill value
+        join_idx = self.frame.index.join(other.index)
+        diff_a = self.frame.index.diff(join_idx)
+        diff_b = other.index.diff(join_idx)
+        diff_a_vals = af.reindex(diff_a).values
+        diff_b_vals = bf.reindex(diff_b).values
+        self.assert_((diff_a_vals == -1).all())
+
         af, bf = self.frame.align(other, join='inner', axis=1)
         self.assert_(bf.columns.equals(other.columns))
 

pandas/tests/test_series.py

@@ -1783,10 +1783,18 @@ def test_apply(self):
         assert_series_equal(result, self.ts * 2)
 
     def test_align(self):
-        def _check_align(a, b, how='left'):
-            aa, ab = a.align(b, join=how)
-
+        def _check_align(a, b, how='left', fill=None):
+            aa, ab = a.align(b, join=how, fill_value=fill)
+                        
             join_index = a.index.join(b.index, how=how)
+            if fill is not None:
+                diff_a = aa.index.diff(join_index)                
+                diff_b = ab.index.diff(join_index)
+                if len(diff_a) > 0:
+                    self.assert_((aa.reindex(diff_a) == fill).all())
+                if len(diff_b) > 0:
+                    self.assert_((ab.reindex(diff_b) == fill).all())
+
             ea = a.reindex(join_index)
             eb = b.reindex(join_index)
 
@@ -1795,6 +1803,7 @@ def _check_align(a, b, how='left'):
 
         for kind in JOIN_TYPES:
             _check_align(self.ts[2:], self.ts[:-5])
+            _check_align(self.ts[2:], self.ts[:-5], -1)
 
             # empty left
             _check_align(self.ts[:0], self.ts[:-5])