Python MapReduce

Hadoop can be downloaded and installed from We'll be using the Hadoop streaming API to execute our Python MapReduce program in Hadoop. The Hadoop Streaming API helps in using any program that has a standard input and output as a MapReduce program.

We'll be writing three MapReduce programs using Python, they are as follows:

  • A basic word count
  • Getting the sentiment Score of each review
  • Getting the overall sentiment score from all the reviews

The basic word count

We'll start with the word count MapReduce. Save the following code in a file:

import sys
for l in sys.stdin:
    # Trailing and Leading white space is removed
    l = l.strip()

    # words in the line is split
    word_tokens = l.split()

 # Key Value ...

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