利用python進行MapReduce時，可能會遇到報如下錯誤：
java.io.IOException: Cannot run program “e_mapper.py”: error=2, No such file or directory
解決辦法是用如下命令運行mapper.py和reducer.py:
hadoop jar /home/hdfs/project/hadoop-2.6.1/contrib/hadoop-streaming-2.6.1.jar -D stream.non.zero.exit.is.failure=false -mapper “python emapper.py” -reducer “python ereducer.py” -input /input/* -output /output -file /home/hdfs/emotionanalysis/emapper.py -file /home/hdfs/emotionanalysis/ereducer.py