2. RPS selection

2.1. Python Game design

The image shows all 9 combinations of moves.

Firstly, work out all the if and elif statements for the 9 possible move combinations.

The first two are below:

if human_move == 'rock' and computer_move == 'rock':

``elif human_move == ‘rock’ and computer_move == ‘paper:’

The computer makes a random choice from the list using random.choice(['rock', 'paper', 'scissors']).

The user is asked to input one of rock, paper or scissors.

The choices are printed.

The choices are compared using if and multiple elif statements.

import random


while True:
    computer_move = random.choice(['rock', 'paper', 'scissors'])
    human_move = input('Type your move: rock, paper or scissors. ')

    print('Human Played: ' + human_move)
    print('Computer Played: ' + computer_move)

    if human_move == 'rock' and computer_move == 'rock':
        print('Tie!')
    elif human_move == 'rock' and computer_move == 'paper':
        print('Computer Wins!')
    elif human_move == 'rock' and computer_move == 'scissors':
        print('Human Wins!')

    elif human_move == 'paper' and computer_move == 'rock':
        print('Human Wins!')
    elif human_move == 'paper' and computer_move == 'paper':
        print('Tie!')
    elif human_move == 'paper' and computer_move == 'scissors':
        print('Computer Wins!')

    elif human_move == 'scissors' and computer_move == 'rock':
        print('Computer Wins!')
    elif human_move == 'scissors' and computer_move == 'paper':
        print('Human Wins!')
    elif human_move == 'scissors' and computer_move == 'scissors':
        print('Tie!')

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2.2. Python Game design: nested if

Nested if statements are used by firstly checking the value of the human move, then checking the computer move within the nested code.

import random


while True:
    computer_move = random.choice(['rock', 'paper', 'scissors'])
    human_move = input('Type your move: rock, paper or scissors. ')

    print('Human Played: ' + human_move)
    print('Computer Played: ' + computer_move)

    if human_move == 'rock':
        if computer_move == 'rock':
            print('Tie!')
        elif computer_move == 'paper':
            print('Computer Wins!')
        elif computer_move == 'scissors':
            print('Human Wins!')

    elif human_move == 'paper':
        if computer_move == 'rock':
            print('Human Wins!')
        elif computer_move == 'paper':
            print("Tie!")
        elif computer_move == 'scissors':
            print('Computer Wins!')

    elif human_move == 'scissors':
        if computer_move == 'rock':
            print('Computer Wins!')
        elif computer_move == 'paper':
            print('Human Wins!')
        elif computer_move == 'scissors':
            print("Tie!")

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Tasks

1. Modify the python code to allow the user to input R, P or S instead of rock, paper or scissors.

2. Modify the python code to print R, P or S instead of the rock, paper or scissors.

3. Add checking of the user input in the python code so that only R, P or S is accepted, and print a message to type one of them if a user inputs something different.

4. Add counters so that the total wins, losses and draws is printed after each game in python.

5. Add if-else in the python game to ask to continue playing and break out of the while True loop if the response is N for No.

6. Modify the code to ask for the number of games to play and replace the while True loop with a for-loop for the entered number of games.

---

2.3. Microbit version

The Microbit version of the game code, using selection, is below.

from microbit import *
import random


display.scroll('A for R   B for S   A&B for P', delay=80)

while True:
    microbit_move = random.choice(['R', 'P', 'S'])
    while True:
        # short pause to allow time to hold down 2 buttons
        sleep(300)
        if button_a.is_pressed() and button_b.is_pressed():
            human_move = 'R'
            break
        elif button_a.is_pressed():
            human_move = 'S'
            break
        elif button_b.is_pressed():
            human_move = 'P'
            break

    display.scroll(human_move + ' v ' + microbit_move, delay=60)

    if human_move == 'R' and microbit_move == 'R':
        display.show(Image.MEH)
    elif human_move == 'R' and microbit_move == 'P':
        display.show(Image.NO)
    elif human_move == 'R' and microbit_move == 'S':
        display.show(Image.YES)

    elif human_move == 'P' and microbit_move == 'R':
        display.show(Image.YES)
    elif human_move == 'P' and microbit_move == 'P':
        display.show(Image.MEH)
    elif human_move == 'P' and microbit_move == 'S':
        display.show(Image.NO)

    elif human_move == 'S' and microbit_move == 'R':
        display.show(Image.NO)
    elif human_move == 'S' and microbit_move == 'P':
        display.show(Image.YES)
    elif human_move == 'S' and microbit_move == 'S':
        display.show(Image.MEH)

    sleep(500)
    display.clear()

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Tasks

1. Modify the microbit code so that after the first game, arrows to the A button and B button are shown to prompt the user to play another game.

2. Add counters so that the total wins, losses and ties is scrolled after each game. e.g. ‘W3 L2 T4’

3. Use if-else after each game to ask to continue playing by pressing the A button or to exit by pressing the B button.

4. Modify the display of the R, P or S to use custom images instead.