AIM: To Develop a MapReduce program to calculate the frequency of a given word in agiven file
Map Function – It takes a set of data and converts it into another set of data, where individual
elements are broken down into tuples (Key-Value pair).
Example – (Map function in Word Count)
Input
Set of data
Bus, Car, bus, car, train, car, bus, car, train, bus, TRAIN,BUS, buS, caR, CAR, car, BUS, TRAIN
Output
Convert into another set of data
(Key,Value)
(Bus,1), (Car,1), (bus,1), (car,1), (train,1), (car,1), (bus,1), (car,1), (train,1), (bus,1),
(TRAIN,1),(BUS,1), (buS,1), (caR,1), (CAR,1), (car,1), (BUS,1), (TRAIN,1)
Reduce Function – Takes the output from Map as an input and combines those data tuples
into a smaller set of tuples.
Example – (Reduce function in Word Count)
Input Set of Tuples
(output of Map function)
(Bus,1), (Car,1), (bus,1), (car,1), (train,1), (car,1), (bus,1), (car,1), (train,1), (bus,1),
(TRAIN,1),(BUS,1),
(buS,1),(caR,1),(CAR,1), (car,1), (BUS,1), (TRAIN,1)
Output Converts into smaller set of tuples
(BUS,7), (CAR,7), (TRAIN,4)
Work Flow of Program