[SPARK-16992][PYSPARK] use map comprehension in doc

Code is equivalent, but map comprehency is most of the time faster than a map.

Author: Gaetan Semet <gaetan@xeberon.net>

Closes #14863 from Stibbons/map_comprehension.

examples/src/main/python/ml/quantile_discretizer_example.py

@@ -29,7 +29,7 @@ if __name__ == "__main__":
         .getOrCreate()
 
     # $example on$
-    data = [(0, 18.0,), (1, 19.0,), (2, 8.0,), (3, 5.0,), (4, 2.2,)]
+    data = [(0, 18.0), (1, 19.0), (2, 8.0), (3, 5.0), (4, 2.2)]
     df = spark.createDataFrame(data, ["id", "hour"])
     # $example off$
 

examples/src/main/python/ml/vector_slicer_example.py

@@ -32,8 +32,8 @@ if __name__ == "__main__":
 
     # $example on$
     df = spark.createDataFrame([
-        Row(userFeatures=Vectors.sparse(3, {0: -2.0, 1: 2.3}),),
-        Row(userFeatures=Vectors.dense([-2.0, 2.3, 0.0]),)])
+        Row(userFeatures=Vectors.sparse(3, {0: -2.0, 1: 2.3})),
+        Row(userFeatures=Vectors.dense([-2.0, 2.3, 0.0]))])
 
     slicer = VectorSlicer(inputCol="userFeatures", outputCol="features", indices=[1])
 

examples/src/main/python/sql/hive.py

@@ -79,7 +79,7 @@ if __name__ == "__main__":
 
     # You can also use DataFrames to create temporary views within a SparkSession.
     Record = Row("key", "value")
-    recordsDF = spark.createDataFrame(map(lambda i: Record(i, "val_" + str(i)), range(1, 101)))
+    recordsDF = spark.createDataFrame([Record(i, "val_" + str(i)) for i in range(1, 101)])
     recordsDF.createOrReplaceTempView("records")
 
     # Queries can then join DataFrame data with data stored in Hive.