HackerRank MapReduce - Word Counts

Explanation Video Link on Youtube

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# This template is based on the framework supplied for a similar challenge, in a Coursera Data Science course: https://www.coursera.org/course/datasci
# And the code supplied here: https://github.com/uwescience/datasci_course_materials/blob/master/assignment3/wordcount.py
import json
import sys
from collections import OrderedDict
class MapReduce:
    def __init__(self):
        self.intermediate = OrderedDict()
        self.result = []

    def emitIntermediate(self, key, value):
        self.intermediate.setdefault(key, [])
        self.intermediate[key].append(value)

    def emit(self, value):
        self.result.append(value) 

    def execute(self, data, mapper, reducer):
        for line in data:
            record = json.loads(line)
            mapper(record)

        for key in self.intermediate:
            reducer(key, self.intermediate[key])

        for item in self.result:
            print "{\"key\":\""+item[0]+"\",\"value\":" + str(item[1]) + "}"

mapReducer = MapReduce()

def mapper(record):
    key = record["key"]
    value = record["value"]
    words = value.split()
    for w in words:		
      mapReducer.emitIntermediate(w, 1)

def reducer(key, list_of_values):
    total = 0
    
    for v in list_of_values:
      total += v

    mapReducer.emit((key, total))

if __name__ == '__main__':
  inputData = []
  counter = 0
  for line in sys.stdin:
	counter += 1
	inputData.append(json.dumps({"key":counter,"value":line}))
  mapReducer.execute(inputData, mapper, reducer)