Raspberry Pi Projects for Kids by Inconnu(e)

Author:Inconnu(e) [Inconnu(e)]
Language: fra
Format: epub
Tags: Informatique
Publisher: O'Reilly
Published: 2014-03-19T07:43:08+00:00

Chapter 3

To run a piece of Python code, open IDLE on the Raspberry Pi desktop. Type the previous code into IDLE and you should notice that it can recognize how many spaces to start a line with. When you have finished, press Enter a couple of times, until you see >>>. This shows that Python recognizes that your block of code has completed, and that it is ready to receive a new command. Now, you can run your code by typing in count(5) and pressing Enter. You can change the 5 to any number you like. We're now ready to create our game!

Coding the game

Here's a quick recap on how this example game is going to work. The Raspberry Pi will choose a random button and ask the player to press it. Every time the player presses the right button, they get a point, and every time they press a wrong button, they lose a point. Once the right button has been pressed, the Raspberry Pi selects a new button as the target. The aim is to score as many points as possible in 30 seconds.

In IDLE, navigate to File | New Window. This will bring up a new empty window, which is where all our code will go. This window is better for editing existing code, and I will call it the Edit window. Whenever you want to test or run your code, navigate to Run | Run Module, or press F5 on your keyboard. This will take you back to the first window, which I will call the Shell, with the code ready to run.

Random behavior

The first job, then, is to write some code that will choose a random button for the player to press. Take a look at the following code snippet. There are a few new things here, so we'll go through them one by one afterwards.

import random

options = [22, 23, 24, 25]

def nexttarget():

target = random.choice(options)

print target

return target

On the first line of the code, we import the random module. Python comes with a huge amount of code that other people have written for us, separated into different modules. Some of this code is simple, but makes life more convenient for us, and some of it is complex, allowing us to reuse other people's solutions to the challenges we face and concentrate on exactly what we want to do. In this case, we are making use of a collection of functions that deal with random behavior. We must import a module before we are able to access its contents. Information on the default modules available can be found online.

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