Windbag MapReduce Application

Motivation

A simple Mapper and two simple ClassicReducers reinforce our understanding of how pieces of the MapReduce puzzle can be reused. Further, we will reduce the value type of List<Boolean> to both an Integer and a Double in separate Reducers.

Background

A windbag is an exhaustively talkative person. Act I Scene 3 of Hamlet has a famous example.

In this assignment we will try to determine who is the biggest windbag in a particular play with Hamlet and The Importance of Being Earnest serving as two pieces of data.

Code To Implement

WindbagMapper

class:	WindbagMapper.java
methods:	windbagLinePredicate map
package:	mapreduce.apps.windbag.studio
source folder:	student/src/main/java

constructor and instance variable

method: public WindbagMapper(IntPredicate windbagLinePredicate) (sequential implementation only)

Hang onto the value of the windbagLinePredicate parameter as an instance variable for later use.

windbagLinePredicate

This method exists largely as a reminder to use the windbagLinePredicate passed to the constructor.

map

Note: the WindBagMapper is constructed with an IntPredicate. This IntPredicate's test method should be invoked to determine if a PlayLine's word count qualifies it as a windbag line. You can investigate the PlayLine class to see what information it contains.

method: public List<Map.Entry<PlayRole, Boolean>> map(PlayLine item) (sequential implementation only)

TrueCountClassicReducer

This Collector reduces to the number of emitted trues.

For example, if a total of eight (8) values were emitted for a particular key and three (3) of them were true:

[false, true, false, false, true, true, false, false]

then the reduced value would be 3

class:	TrueCountClassicReducer.java
methods:	reduce
package:	mapreduce.apps.windbag.exercise
source folder:	student/src/main/java

method: public Integer reduce(List<Boolean> container) (sequential implementation only)

Warning:This class inherits from ClassicReducer. Be sure to have completed that studio first.

TruePortionClassicReducer

This Collector reduces to the portion of emitted trues.

For example, if a total of eight (8) values were emitted for a particular key and three (3) of them were true:

[false, true, false, false, true, true, false, false]

then the reduced value would be 0.375

class:	TruePortionClassicReducer.java
methods:	reduce
package:	mapreduce.apps.windbag.exercise
source folder:	student/src/main/java

method: public Double reduce(List<Boolean> container) (sequential implementation only)

Warning:This class inherits from ClassicReducer. Be sure to have completed that studio first.

Testing Your Solution

Correctness

class:	WindbagStudioTestSuite.java
package:	mapreduce
source folder:	testing/src/test/java

Output

class:	WindbagApp.java
package:	mapreduce.apps.windbag.client
source folder:	src/main/java

           COUNT
===========================
      HAMLET: 27
        KING: 14
    POLONIUS:  7
     HORATIO:  5
     OPHELIA:  2
       GHOST:  2
FIRST PLAYER:  2
     LAERTES:  1
 ROSENCRANTZ:  1
   VOLTEMAND:  1
 PLAYER KING:  1
   GENTLEMAN:  1
PLAYER QUEEN:  1
       QUEEN:  1



          PORTION
===========================
   VOLTEMAND: 1.000000
   GENTLEMAN: 0.333333
 PLAYER KING: 0.250000
FIRST PLAYER: 0.250000
PLAYER QUEEN: 0.200000
       GHOST: 0.142857
        KING: 0.137255
    POLONIUS: 0.081395
      HAMLET: 0.075419
     HORATIO: 0.046729
     OPHELIA: 0.034483
 ROSENCRANTZ: 0.022222
     LAERTES: 0.016129
       QUEEN: 0.014493