基本流程为:
cat data | map | sort | reduce
cat devProbe | ./mapper.py | sort| ./reducer.py
echo "foo foo quux labs foo bar quux" | ./mapper.py | sort -k1,1 | ./reducer.py
# -k, -key=POS1[,POS2] 键以pos1开始,以pos2结束
如不执行下述命令,可以再py文件前加上python调用
chmod +x mapper.py
chmod +x reducer.py
对于分布式环境下,可以使用以下命令:
hadoop jar /[YOUR_PATH]/hadoop/tools/lib/hadoop-streaming-2.6.0-cdh5.4.4.jar
-file mapper.py -mapper mapper.py
-file reducer.py -reducer reducer.py
-input [IN_FILE] -output [OUT_DIR]
mapper.py
#!/usr/bin/python # -*- coding: UTF-8 -*- __author__ = 'Manhua' import sys for line in sys.stdin: line = line.strip() item = line.split('`') print "%s %s" % (item[0]+'`'+item[1], 1)
reducer.py
#!/usr/bin/python # -*- coding: UTF-8 -*- __author__ = 'Manhua' import sys current_word = None current_count = 0 word = None for line in sys.stdin: line = line.strip() word, count = line.split(' ', 1) try: count = int(count) except ValueError: #count如果不是数字的话,直接忽略掉 continue if current_word == word: current_count += count else: if current_word: print "%s %s" % (current_word, current_count) current_count = count current_word = word if word == current_word: #不要忘记最后的输出 print "%s %s" % (current_word, current_count)