https://blog.csdn.net/u013019431/article/details/80776662   在jupyter notebook import pyspark
https://www.douban.com/note/504421303/ 如何初始化

https://blog.csdn.net/dream_an/article/details/51935530 只能创建一次SparkContext引发的错误，所以在前面加个 try sc.stop()
https://www.iteblog.com/archives/1240.html  sortBy()  sortByKey()