fix pyspark test error

python/pyspark/sql/functions.py

@@ -1826,13 +1826,13 @@ def map_from_arrays(col1, col2):
     :param col1: name of column containing a set of keys. All elements should not be null
     :param col2: name of column containing a set of values
 
-    >>> df = spark.createDataFrame([([2, 5], ["Alice", "Bob"])], ['k', 'v'])
+    >>> df = spark.createDataFrame([([2, 5], ['a', 'b'])], ['k', 'v'])
     >>> df.select(map_from_arrays(df.k, df.v).alias("map")).show()
-    +----------------------+
-    |                   map|
-    +----------------------+
-    |[2 -> Alice, 5 -> Bob]|
-    +----------------------+
+    +----------------+
+    |             map|
+    +----------------+
+    |[2 -> a, 5 -> b]|
+    +----------------+
     """
     sc = SparkContext._active_spark_context
     return Column(sc._jvm.functions.map_from_arrays(_to_java_column(col1), _to_java_column(col2)))