Doc: Add example of merging a Series with a Dataframe

doc/source/merging.rst

@@ -714,6 +714,31 @@ either the left or right tables, the values in the joined table will be
  labels=['left', 'right'], vertical=False);
  plt.close('all');
 
+To join a Series and a DataFrame, the Series has to be transformed into a DataFrame first:
+
+.. ipython:: python
+
+ df = pd.DataFrame({"Let": ["A", "B", "C"], "Num": [1, 2, 3]})
+ df
+
+ # The series has a multi-index with levels corresponding to columns in the DataFrame we want to merge with
+ ser = pd.Series(
+ ['a', 'b', 'c', 'd', 'e', 'f'],
+ index=pd.MultiIndex.from_arrays([["A", "B", "C"]*2, [1, 2, 3, 4, 5, 6]])
+ )
+ ser
+
+ # Name the row index levels
+ ser.index.names=['Let','Num']
+ ser
+
+ # reset_index turns the multi-level row index into columns, which requires a DataFrame
+ df2 = ser.reset_index()
+ type(df2)
+
+ # Now we merge the DataFrames
+ pd.merge(df, df2, on=['Let','Num'])
+
 Here is another example with duplicate join keys in ``DataFrame``s:
 
 .. ipython:: python