rock-Spock-paper-lizard-scissors

# rock-Spock-paper-lizard-scissors game
# Ode to Big Bang Theory television show
# http://www.codeskulptor.org/#user2-LHdperqFop-0.py
# Heidi A. Heffelfinger
# October 16, 2012
# Code is based on Rice University template

# This program determines winner by equating strings:
# "rock", "paper", "scissors", "lizard", "Spock" to numbers
# as follows:
#
# 0 - rock
# 1 - Spock
# 2 - paper
# 3 - lizard
# 4 - scissors

import random

def number_to_name(number):
    '''(int) -> str

    Returns a string matching the corresponding number.
    Precondition: string must be 0, 1, 2, 3, or 4

    >>> number_to_name(0)
    'rock'
    >>> number_to_name(2)
    'paper'
    >>> number_to_name(4)
    'scissors'
    '''

    if (number == 0):
        return 'rock'
    elif (number == 1):
        return 'Spock'
    elif (number == 2):
        return 'paper'
    elif (number == 3):
        return 'lizard'
    elif (number == 4):
        return 'scissors'

def name_to_number(name):
    '''(str) -> int

    Returns an integer between 0 and 4 for given string, name.
    Precondition: name must be 'rock', 'Spock', 'paper', 'lizard', or 'scissors'

    >>> name_to_number('rock')
    0
    >>> name_to_number('paper')
    2
    >>> name_to_number('scissors')
    4
    '''

    if (name == 'rock'):
        return 0
    elif (name == 'Spock'):
        return 1
    elif (name == 'paper'):
        return 2
    elif (name == 'lizard'):
        return 3
    elif (name == 'scissors'):
        return 4

def rpsls(guess):
    '''(str) -> str

    Prints player's choice (guess), prints randomly generated computer choice, and
    returns and prints winner between player's choice and computer choice.

    rpsls("rock") ## with random number generation of 1
    >>>
    Player chooses rock
    Computer chooses Spock
    Computer wins!

    rpsls("scissors") ## with random number generation of 4
    >>>
    Player chooses scissors
    Computer chooses scissors
    Player and Computer tie.

    rpsls("lizard") ## with random number generation of 2
    >>>
    Player chooses lizard
    Computer chooses paper
    Player wins!
    '''

    player_number = name_to_number(guess) #converts players guess to number
    comp_number = random.randrange(0,5) #computes a random guess for computer

    win_value = (comp_number - player_number) % 5 #computes win_value
    if win_value == 0: # if difference is 0, both tie
        winner = "Player and Computer tie."
    elif win_value >= 3: # if difference is 3 or 4, the Player wins
        winner = "Player wins!"
    else: # if difference is 1 or 2, the Computer wins
        winner = "Computer wins!"

    # print results
    print("Player chooses " + number_to_name(player_number))
    print("Computer chooses " + number_to_name(comp_number))
    print(winner)
    print()

# test code
rpsls("rock")
rpsls("Spock")
rpsls("paper")
rpsls("lizard")
rpsls("scissors")