Streaming执行Python版WordCount

一：先写map类

import sysfor line in sys.stdin:line = line.strip( )words = line.split( )for word in words:print('%s\t%s' % (word, 1))

二：写reduce类

import syscurrent_word = Nonecurrent_count = 0word = Nonefor line in sys.stdin:line = line.strip()word, count = line.split('\t',1)try:count = int(count)except ValueError:continueif current_word == word:current_count += countelse:if current_word:print('%s\t%s' % (current_word,current_count))current_count = countcurrent_word = wordif current_word == word:print('%s\t%s' % (current_word,current_count))

三：利用hadoop Streaming执行Python的内容。

hadoop jar /home/hadoop/hadoop-2.6.0-cdh6.5.2/share/hadoop/tools/lib/hadoop-streaming-2.6.0-cdh6.5.2.jar -input /user/hadoop/aa.txt -output /user/hadoop/python_output -mapper "python mapper.py" -reducer "python reducer.py" -file mapper.py -file reducer.py

说明：

输入和输出路径，本身就是hdfs上的，不需要特殊指定hdfs。

不加×××部分的引号的话，会报错误：

Error: java.lang.RuntimeException: PipeMapRed.waitOutputThreads(): subprocess failed with code 2

不加粉色部分的内容的话，会报错误：

Error: java.lang.RuntimeException: Error in configuring object