Address requested changes

Author: Albert Villanova del Moral

doc/source/whatsnew/v0.20.0.txt

@@ -751,38 +751,38 @@ joins (methods ``DataFrame.join`` and ``pd.merge``) and the .align methods.
 
   .. ipython:: python
 
-     idx1 = pd.Index([2, 1, 0])
-     idx1
-     idx2 = pd.Index([1, 2, 3])
-     idx2
+     left = pd.Index([2, 1, 0])
+     left
+     right = pd.Index([1, 2, 3])
+     right
 
   Previous Behavior:
 
   .. code-block:: ipython
 
-     In [4]: idx1.intersection(idx2)
+     In [4]: left.intersection(right)
      Out[4]: Int64Index([1, 2], dtype='int64')
 
   New Behavior:
 
   .. ipython:: python
 
-     idx1.intersection(idx2)
+     left.intersection(right)
 
 - ``DataFrame.join`` and ``pd.merge``
 
   .. ipython:: python
 
-     df1 = pd.DataFrame({'a': [20, 10, 0]}, index=[2, 1, 0])
-     df1
-     df2 = pd.DataFrame({'b': [100, 200, 300]}, index=[1, 2, 3])
-     df2
+     left = pd.DataFrame({'a': [20, 10, 0]}, index=[2, 1, 0])
+     left
+     right = pd.DataFrame({'b': [100, 200, 300]}, index=[1, 2, 3])
+     right
 
   Previous Behavior:
 
   .. code-block:: ipython
 
-     In [4]: df1.join(df2, how='inner')
+     In [4]: left.join(right, how='inner')
      Out[4]:
          a    b
      1  10  100
@@ -792,7 +792,7 @@ joins (methods ``DataFrame.join`` and ``pd.merge``) and the .align methods.
 
   .. ipython:: python
 
-     df1.join(df2, how='inner')
+     left.join(right, how='inner')
 
 
 .. _whatsnew_0200.api:

pandas/core/frame.py

@@ -124,14 +124,14 @@
 ----------%s
 right : DataFrame
 how : {'left', 'right', 'outer', 'inner'}, default 'inner'
-    * left: use only keys from left frame (SQL: left outer join), preserving
-      their order
-    * right: use only keys from right frame (SQL: right outer join), preserving
-      their order
-    * outer: use union of keys from both frames (SQL: full outer join), and
-      sort them lexicographically
-    * inner: use intersection of keys from both frames (SQL: inner join),
-      preserving the order of the left keys
+    * left: use only keys from left frame, similar to a SQL left outer join;
+      preserve key order
+    * right: use only keys from right frame, similar to a SQL right outer join;
+      preserve key order
+    * outer: use union of keys from both frames, similar to a SQL full outer
+      join; sort keys lexicographically
+    * inner: use intersection of keys from both frames, similar to a SQL inner
+      join; preserve the order of the left keys
 on : label or list
     Field names to join on. Must be found in both DataFrames. If on is
     None and not merging on indexes, then it merges on the intersection of

pandas/tests/frame/test_join.py

@@ -14,12 +14,12 @@ def frame():
 
 
 @pytest.fixture
-def df1():
+def left():
     return DataFrame({'a': [20, 10, 0]}, index=[2, 1, 0])
 
 
 @pytest.fixture
-def df2():
+def right():
     return DataFrame({'b': [300, 100, 200]}, index=[3, 1, 2])
 
 
@@ -49,9 +49,9 @@ def df2():
      ('outer', True, DataFrame({'a': [0, 10, 20, np.nan],
                                 'b': [np.nan, 100, 200, 300]},
                                index=[0, 1, 2, 3]))])
-def test_join(df1, df2, how, sort, expected):
+def test_join(left, right, how, sort, expected):
 
-    result = df1.join(df2, how=how, sort=sort)
+    result = left.join(right, how=how, sort=sort)
     tm.assert_frame_equal(result, expected)
 
 

pandas/tests/tools/test_merge.py

@@ -1358,13 +1358,13 @@ def test_dtype_on_merged_different(self, change, how, left, right):
 
 
 @pytest.fixture
-def df1():
+def left():
     return DataFrame({'a': [20, 10, 0]}, index=[2, 1, 0])
 
 
 @pytest.fixture
-def df2():
-    return DataFrame({'b': [100, 200, 300]}, index=[1, 2, 3])
+def right():
+    return DataFrame({'b': [300, 100, 200]}, index=[3, 1, 2])
 
 
 class TestMergeOnIndexes(object):
@@ -1383,8 +1383,8 @@ class TestMergeOnIndexes(object):
          ('left', True, DataFrame({'a': [0, 10, 20],
                                    'b': [np.nan, 100, 200]},
                                   index=[0, 1, 2])),
-         ('right', False, DataFrame({'a': [10, 20, np.nan],
-                                     'b': [100, 200, 300]},
+         ('right', False, DataFrame({'a': [np.nan, 10, 20],
+                                     'b': [300, 100, 200]},
                                     index=[1, 2, 3])),
          ('right', True, DataFrame({'a': [10, 20, np.nan],
                                     'b': [100, 200, 300]},
@@ -1395,9 +1395,9 @@ class TestMergeOnIndexes(object):
          ('outer', True, DataFrame({'a': [0, 10, 20, np.nan],
                                     'b': [np.nan, 100, 200, 300]},
                                    index=[0, 1, 2, 3]))])
-    def test_merge_on_indexes(self, df1, df2, how, sort, expected):
+    def test_merge_on_indexes(self, left, right, how, sort, expected):
 
-        result = pd.merge(df1, df2,
+        result = pd.merge(left, right,
                           left_index=True,
                           right_index=True,
                           how=how,