RDD flatMap 操作例子：

flatMap，对原RDD的每个元素(行)执行函数操作，然后把每行都“拍扁”

[training@localhost ~]$ hdfs dfs -put cats.txt
[training@localhost ~]$ hdfs dfa -cat cats.txt
Error: Could not find or load main class dfa
[training@localhost ~]$ hdfs dfs -cat cats.txt
The cat on the mat
The aardvark sat on the sofa

mydata=sc.textFile("cats.txt")

mydata.count()
Out[14]: 2

mydata.take(2)
Out[15]: [u'The cat on the mat', u'The aardvark sat on the sofa']

myflatdata=mydata.flatMap(lambda line: line.split(' '))
myflatdta.count()
Out[19]: 11

myflatdata.take(2)
Out[20]: [u'The', u'cat']

myflatdata.take(11)
Out[21]:
[u'The',
u'cat',
u'on',
u'the',
u'mat',
u'The',
u'aardvark',
u'sat',
u'on',
u'the',
u'sofa']