Rock-paper-scissors
is a hand game that is played by two people. The players count to three in
unison and simultaneously 'throw' one of three hand signals that
correspond to rock, paper or scissors. The winner is determined by the rules:
·
Rock smashes scissors
·
Scissors cuts paper
·
Paper covers rock
Rock-paper-scissors
is a surprisingly popular game that many people play seriously (see the Wikipedia article for details). Due to the fact that a tie
happens around 1/3 of the time, several variants of Rock-Paper-Scissors exist
that include more choices to make ties more unlikely.
Rock-paper-scissors-lizard-Spock
(RPSLS) is a variant of Rock-paper-scissors that allows five choices. Each
choice wins against two other choices, loses against two other choices and ties
against itself. Much of RPSLS's popularity is that it has been featured in 3
episodes of the TV series "The Big Bang Theory". The Wikipedia entry for RPSLS
gives the complete description of the details of the game.
In our first
mini-project, we will build a Python function rpsls(name) that takes as input the string name, which is one
of "rock","paper", "scissors", "lizard", or "Spock". The function then simulates playing a round of
Rock-paper-scissors-lizard-Spock by generating its own random choice from these
alternatives and then determining the winner using a simple rule that we will
next describe.
While
Rock-paper-scissor-lizard-Spock has a set of ten rules that logically determine
who wins a round of RPSLS, coding up these rules would require a large number
(5x5=25) of if/elif/else clauses in your mini-project
code. A simpler method for determining the winner is to assign each of the five
choices a number:
·
0 — rock
·
1 — Spock
·
2 — paper
·
3 — lizard
·
4 — scissors
In this expanded
list, each choice wins against the preceding two choices and loses against the
following two choices.
1. Build a helper
function name_to_number(name) that converts the string name into a number between 0 and 4 as described above. This function
should use a sequence of if/elif/else clauses. You can use conditions
of the form name == 'paper', etc. to distinguish the cases.To
make debugging your code easier, we suggest including a final else clause that catches cases whenname does not match any of the five
correct input strings and prints an appropriate error message.
2. Next, you should
build a second helper function number_to_name(num) that converts
a number in the range 0 to 4 into its corresponding name as a string. Again, we
suggest including a final else clause that catches cases
when number is not in the correct range.
3. Build the first
part of the main function rpsls(name) that
converts name into the number player_number between 0 and 4 using the helper function name_to_number.
4. Build the second
part of rpsls(name) that generates a random
number comp_number between 0 and 4 using the
functionrandom.randrange(). I suggest experimenting with randrange in a separate CodeSkulptor window before deciding on how to call
it to make sure that you do not accidently generate numbers in the wrong range.
5. Build the last part
of rpsls(name) that determines and prints out
the winner. This test is actually very simple if you use the remainder
operation (% in Python) to the difference between comp_number and player_number. If this is not
immediately obvious to you, I would suggest reviewing the "More
operations" and "RPSLS" videos on remainders and modular
arithmetic as well as experimenting with the remainder operator % in a separate CodeSkulptor window to understand its behavior.
6. Using the helper
function number_to_name, you should produce four print statements; print a blank line, print out the player's choice,
print out the computer's choice and print out the winner.
This will be the only mini-project in the class that is not an interactive game. Since we have not yet learned enough to allow you to play the game interactively, you will simply call your rpsls function repeatedly in the program with different player choices. You will see that we have provided five such calls at the bottom of the template. Running your program repeatedly should generate different computer guesses and different winners each time. While you are testing, feel free to modify those calls, but make sure they are restored when you hand in your mini-project, as your peer assessors will expect them to be there.
The output of
running your program should have the following form:
Player chooses rock
Computer chooses scissors
Player wins!
Player chooses Spock
Computer chooses lizard
Computer wins!
Player chooses paper
Computer chooses lizard
Computer wins!
Player chooses lizard
Computer chooses scissors
Computer wins!
Player chooses scissors
Computer chooses Spock
Computer wins!
Answer : Access my code here
