Merge pull request #2572 from szarnyasg/iss2571

Relational API on Pandas: Add missing where clause

docs/guides/python/relational_api_pandas.md

@@ -19,7 +19,7 @@ input_df = pandas.DataFrame.from_dict({'i': [1, 2, 3, 4],
 rel = con.from_df(input_df)
 
 # chain together relational operators (this is a lazy operation, so the operations are not yet executed)
-# equivalent to: SELECT i, j, i*2 AS two_i FROM input_df ORDER BY i DESC LIMIT 2
+# equivalent to: SELECT i, j, i*2 AS two_i FROM input_df WHERE i >= 2 ORDER BY i DESC LIMIT 2
 transformed_rel = rel.filter('i >= 2').project('i, j, i*2 as two_i').order('i desc').limit(2)
 
 # trigger execution by requesting .df() of the relation