将 rdd 转换为数据帧：AttributeError: 'RDD' 对象没有属性 'toDF'

Question

from pyspark import SparkContext, SparkConf
from pyspark.sql import SQLContext

conf = SparkConf().setAppName("myApp").setMaster("local")
sc = SparkContext(conf=conf)

a = sc.parallelize([[1, "a"], [2, "b"], [3, "c"], [4, "d"], [5, "e"]]).toDF(['ind', "state"])

a.show()

结果是：

Traceback (most recent call last):
  File "/Users/ktemlyakov/messing_around/SparkStuff/mock_maersk_data.py", line 7, in <module>
    a = sc.parallelize([[1, "a"], [2, "b"], [3, "c"], [4, "d"], [5, "e"]]).toDF(['ind', "state"])
AttributeError: 'RDD' object has no attribute 'toDF'

我错过了什么？

Answer 1

sqlContext不见了; 它需要被创建。以下代码有效：

from pyspark import SparkContext, SparkConf
from pyspark.sql import SQLContext
from pyspark import sql

conf = SparkConf().setAppName("myFirstApp").setMaster("local")
sc = SparkContext(conf=conf)
sqlContext = sql.SQLContext(sc)

a = sc.parallelize([[1, "a"], [2, "b"], [3, "c"], [4, "d"], [5, "e"]]).toDF(['ind', "state"])

a.show()

编辑：

在 Spark 2.0 中，以上可以通过以下方式实现：

from pyspark import SparkConf
from pyspark.sql import SparkSession

spark = SparkSession.builder.master("local").config(conf=SparkConf()).getOrCreate()

a = spark.createDataFrame([[1, "a"], [2, "b"], [3, "c"], [4, "d"], [5, "e"]], ['ind', "state"])
a.show()