Tutorial for MAHacks Oct 2019
Making a rock-paper-scissor game in Python while learning about Git and Github.
- Learn basic Python syntax
- Learn about refactoring
- Learn about version control, specifically Git
- Learn about some of Githubs cool features
On the project page press the "Fork" button on the upper right hand side. This means that you will have your own copy of the repository in your Github account. You are free to modify as you wish and you can even merge your code back to the original repository through a concept we will learn a bit later, called Pull Requests
Once you have your forked repo clone it from the remote onto your computer.
In the terminal (or git bash if you are on windows):
$ git clone https://github.com/<USERNAME>/python-git-tutorial.git
$ cd python-git-tutorial
$ ls
-- or --
$ dir
You should have the License and the REAME.md
Its time to make some changes! Let's start by create a new branch. Branches are versions of the code. Whenever you want to make a change to your code you should create a new branch. If your code in your branch gets messed up you can just delete it and try again. This means that your master branch will always be clean.
$ git checkout -b new-branch
$ git branch
You should now see that your new-branch is active. Pick your favorite editor and create a new file in here called run.py
Create a new file in your favorite editor and call it run.py
print("Hello World")
Save the file.
python run.py
If you see the output Hello World in you terminal, congrats!
Delete the previous print statement and lets start the game by getting player input.
player = input('rock (r), paper (p) or scissors (s)?')
if player == 'r':
print('O', end=' ')
elif player == 'p':
print('___', end=' ')
elif player == 's':
print('>8', end=' ')
else:
print('??')
print('vs', end=' ')
We are going to import a standard Python library. Importing libraries let's you build on code that has already been written. You can use the standard library or install a library to use through the package manager, pip.
Imports should always got at the top of the file. Below import the randint function from the random library and add the code for the computer to pick below your player code.
from random import randint
...
chosen = randint(1,3)
if chosen == 1 :
computer = 'r'
print('O')
elif chosen == 2 :
computer = 'p'
print('___')
else:
computer = 's'
print('>8')
After the computer is going to pick a random number to determine which choice it makes. When then have to map it to a letter so that we can compare against the player.
chosen = randint(1,3)
if chosen == 1 :
computer = 'r'
print('O')
elif chosen == 2 :
computer = 'p'
print('___')
else:
computer = 's'
print('>8')
Then we compare to the players choice:
if player == computer:
print('DRAW!')
elif player == 'r' and computer == 's':
print('Player wins!')
elif player == 'r' and computer == 'p':
print('Computer wins!')
elif player == 'p' and computer == 'r':
print('Player wins!')
elif player == 'p' and computer == 's':
print('Computer wins!')
elif player == 's' and computer == 'p':
print('Player wins!')
elif player == "s" and computer == 'r':
print('Computer wins!')
else:
print('Huh?')
python run.py
git add run.py
git commit -m 'My first commit'
git push
You should get an error:
fatal: The current branch new-branch has no upstream branch.
To push the current branch and set the remote as upstream, use
git push --set-upstream origin new-branch
Run the suggested command to push your branch to the remote.
Pull requests are one of the most powerful features of git hub. To make a pull request press the New Pull Request button.
The base should be the branch you want to merge changes into. In this case its's master. Compare will be new-branch.
Once you set this up you should see the contents of the run.py. This is a really useful tool to review your code, or a code your buddy wants to merge.
When you are ready hit Merge pull request.
In your terminal:
$ git checkout -b refactor-play-game
Python supports single and multi-line comments as seen below. The comments explain some of the common Python conventions.} Since Python is a white space language it is going to be very important to get the spacing correct or it will change how the interpreter reads your code. By convention, Python uses 4 spaces for indentation. You cannot mix tabs and spaces.
from random import randint
# Single Line comment. This is where the game starts
def play_game():
"""
Muli line comment describe this function. This function is the main function for rock, paper, scissors
It was called play_game to illustrate that python style is snake_case not CamelCase
"""
player = input('rock (r), paper (p) or scissors (s)?')
...
else:
computer = 's'
print('>8')
if __name__ == "__main__":
"""
Common for most Python modules. If this is the main program it will run play.
"""
play_game()
Follow steps 11 and 12 in part one to merge your refactored code into the repository
Python has 2 ways to pass parameters to a function: arguments and keyword arguments commonly refered to as args and kwargs. Args are required to be in the same position everytime. Keyword arguments must follow arguments but can be in any order.
Create a new branch for Part 3 and make the following changes:
def play_game(p_score, c_score=0):
print('Welcome to Rock, Paper, Scissors!')
print('The score is player: {score1}, computer: {score2}'
.format(score1=p_score, score2=c_score))
The change we just made will break the game. How do we fix it?
if __name__ == "__main__":
"""
Common for most Python modules. If this is the main program it will run play.
When we first start the game make sure the score is reset.
"""
play_game(0, c_score=0)
We now need to keep score for when the player or the computer wins.
elif player == 'r' and computer == 's':
print('Player wins!')
p_score = p_score + 1
elif player == 'r' and computer == 'p':
print('Computer wins!')
c_score = c_score + 1
elif player == 'p' and computer == 'r':
print('Player wins!')
p_score = p_score + 1
elif player == 'p' and computer == 's':
print('Computer wins!')
c_score = c_score + 1
elif player == 's' and computer == 'p':
print('Player wins!')
p_score = p_score + 1
elif player == "s" and computer == 'r':
print('Computer wins!')
c_score = c_score + 1
if keep_playing == 'y':
play(p_score, c_score)
else:
if p_score > c_score:
print('Player wins with a final score of {}'.format(p_score))
elif p_score < c_score:
print('Computer wins with a final score of {}'.format(c_score))
else:
print("No winner, it's a draw!")
Create a handicap for the player or the computer. Create a best out of 5 game. Allow the user to change the game to be best out of X.