# objrrball.py
# Simulation of a racquet game.
# Illustrates design with objects.
from random import random
class Player:
# A Player keeps track of service probability and score
def __init__(self, prob):
# Create a player with this probability
self.prob = prob
self.score = 0
def winsServe(self):
# Returns True with probability self.prob
return random() <= self.prob
def incScore(self):
# Add a point to this player's score
self.score = self.score + 1
def getScore(self):
# Returns this player's current score
return self.score
class RBallGame:
# A RBallGame represents a game in progress. A game has two players
# and keeps track of which one is currently serving.
def __init__(self, probA, probB):
# Create a new game having players with the given probs.
self.playerA = Player(probA)
self.playerB = Player(probB)
self.server = self.playerA # Player A always serves first
def play(self):
# Play the game to completion
while not self.isOver():
if self.server.winsServe():
self.server.incScore()
else:
self.changeServer()
def isOver(self):
# Returns game is finished (i.e. one of the players has won).
a,b = self.getScores()
return a == 15 or b == 15 or \
(a == 7 and b == 0) or (b==7 and a == 0)
def changeServer(self):
# Switch which player is serving
if self.server == self.playerA:
self.server = self.playerB
else:
self.server = self.playerA
def getScores(self):
# Returns the current scores of player A and player B
return self.playerA.getScore(), self.playerB.getScore()
class SimStats:
# SimStatistics handles accumulation of statistics across multiple
# (completed) games. This version tracks the wins and shutouts for
# each player.
def __init__(self):
# Create a new accumulator for a series of games
self.winsA = 0
self.winsB = 0
self.shutsA = 0
self.shutsB = 0
def update(self, aGame):
# Determine the outcome if aGame and update statistics
a, b = aGame.getScores()
if a > b: # A won the game
self.winsA = self.winsA + 1
if b == 0:
self.shutsA = self.shutsA + 1
else: # B won the game
self.winsB = self.winsB + 1
if a == 0:
self.shutsB = self.shutsB + 1
def printReport(self):
# Print a nicely formatted report
n = self.winsA + self.winsB
print "Summary of", n , "games:"
print
print " wins (% total) shutouts (% wins) "
print "--------------------------------------------"
self.printLine("A", self.winsA, self.shutsA, n)
self.printLine("B", self.winsB, self.shutsB, n)
def printLine(self, label, wins, shuts, n):
template = "Player %s: %4d %5.1f%% %11d %s"
if wins == 0: # Avoid division by zero!
shutStr = "-----"
else:
shutStr = "%4.1f%%" % (float(shuts)/wins*100)
print template % (label, wins, float(wins)/n*100, shuts, shutStr)
def printIntro():
print "This program simulates games of racquetball between two"
print 'players called "A" and "B". The ability of each player is'
print "indicated by a probability (a number between 0 and 1) that"
print "the player wins the point when serving. Player A always"
print "has the first serve.\n"
def getInputs():
# Returns the three simulation parameters
a = input("What is the prob. player A wins a serve? ")
b = input("What is the prob. player B wins a serve? ")
n = input("How many games to simulate? ")
return a, b, n
def main():
printIntro()
probA, probB, n = getInputs()
# Play the games
stats = SimStats()
for i in range(n):
theGame = RBallGame(probA, probB) # create a new game
theGame.play() # play it
stats.update(theGame) # get info about completed game
# Print the results
stats.printReport()
if __name__ == "__main__":
main()
raw_input("\nPress to quit")