[Spark][python]从 web log 中提取出 UserID 作为key 值，形成新的 RDD

针对RDD, 使用 keyBy 来构筑 key-line 对：

[training@localhost ~]$ cat webs.log

56.31.230.188 - 90700 "GET/KDDOC-00101.html HTTP/1.0"
56.32.230.186 - 90700 "GET/contents.css HTTP/1.0"
202.156.27.99 - 25223 "GET /KDDOC-00220.html HTTP/1.0"
[training@localhost ~]$
[training@localhost ~]$ hdfs dfs -put webs.log
[training@localhost ~]$
[training@localhost ~]$ hdfs dfs -cat webs.log
56.31.230.188 - 90700 "GET/KDDOC-00101.html HTTP/1.0"
56.32.230.186 - 90700 "GET/contents.css HTTP/1.0"
202.156.27.99 - 25223 "GET /KDDOC-00220.html HTTP/1.0"
[training@localhost ~]$
[training@localhost ~]$

In [23]: mylogs = sc.textFile("webs.log")

In [25]: mylogs001 = mylogs.keyBy(lambda line: line.split(' ')[2])

In [26]: mylogs001.take(1)
Out[26]: [(u'90700', u'56.31.230.188 - 90700 "GET/KDDOC-00101.html HTTP/1.0"')]

In [28]: mylogs001.take(2)
Out[28]:
[(u'90700', u'56.31.230.188 - 90700 "GET/KDDOC-00101.html HTTP/1.0"'),
(u'90700', u'56.32.230.186 - 90700 "GET/contents.css HTTP/1.0"')]

作一个对比，看看 mylogs001.take(3) 和 mylogs.take(3)

In [30]: mylogs001.take(3)
Out[30]:
[(u'90700', u'56.31.230.188 - 90700 "GET/KDDOC-00101.html HTTP/1.0"'),
(u'90700', u'56.32.230.186 - 90700 "GET/contents.css HTTP/1.0"'),
(u'25223', u'202.156.27.99 - 25223 "GET /KDDOC-00220.html HTTP/1.0"')]

In [31]: mylogs.take(3)
Out[31]:
[u'56.31.230.188 - 90700 "GET/KDDOC-00101.html HTTP/1.0"',
u'56.32.230.186 - 90700 "GET/contents.css HTTP/1.0"',
u'202.156.27.99 - 25223 "GET /KDDOC-00220.html HTTP/1.0"']