reducer.py

import sys
salesTotal = 0.0
oldKey = None
dummy_Data=["Miami 12.34","Miami 99.07","Miami 55.07","NYC 88.97","NYC 33.56"]

for line in dummy_Data:
	data = line.strip().split(" ")
	if len(data) != 2:
		# Something has gone wrong. Skip this line.
		continue

	thisKey, thisSale = data
	if oldKey and oldKey != thisKey:
  		print oldKey, ":", salesTotal
  		oldKey = thisKey
  		salesTotal = 0

	oldKey = thisKey
	salesTotal += float(thisSale)
	
if oldKey != None:
	print oldKey, ":", salesTotal