The “Invent with Python” Blog

• This tutorial is short.
• To figure out bugs in your code, you might put in print statements/print() calls to display the value of variables.
• Don’t do this. Use the Python logging module.

The logging is better than printing because:

• It’s easy to put a timestamp in each message, which is very handy.
• You can have different levels of urgency for messages, and filter how less urgent messages.
• When you want to later find/remove log messages, you won’t get them confused for real print() calls.
• If you just print to a log file, it’s easy to leave the log function calls in and just ignore them when you don’t need them. (You don’t have to constantly pull out print() calls.)

Using print is for coders with too much time on their hands. Use logging instead. Also, learn to use the Python debugger to debug bugs and Pylint to prevent bugs and make your code readable.

To print log messages to the screen, copy and paste this code:

import logging
logging.basicConfig(level=logging.DEBUG, format='%(asctime)s - %(levelname)s - %(message)s')
logging.debug('This is a log message.')

To write log messages to a file, you can copy and paste this code (the only difference is in bold):

import logging
logging.basicConfig(filename='log_filename.txt', level=logging.DEBUG, format='%(asctime)s - %(levelname)s - %(message)s')
logging.debug('This is a log message.')

Later runs of the program will append to the end of the log file, rather than overwrite the file.

To log messages to a file AND printed to the screen, copy and paste the following:
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Here are a couple games I wrote. The first was so popular that I made a sequel:

Win32 EXEs and source:

Look At This Rock

Look At This Rock 2: A Different Rock

Source (requires Pygame to be installed along with Python):

Source: LookAtThisRock.py and PNG

Source: LookAtThisRock2.py and PNG

Screenshots:

I’ve created a web version of the Caesar Cipher wheel using JQuery and CSS sprites.

JavaScript Cipher Wheel

I also have a Pygame version and Windows executable of this.

I wanted to share this link to a great site with some simple Pygame examples:

Python and Pygame Examples

There is also a textbook draft called “Introduction to Computer Science Using Python and Pygame” by Paul Vincent Craven.

“MooseGesture” is a Python module that implements a basic mouse gesture recognition system. It can identify gestures made up of strokes in the eight cardinal and diagonal directions.

A mouse gesture is holding down the mouse button and moving the mouse cursor in a specific pattern to issue a command.
Mouse gestures are a way of dragging with the mouse in order to draw out a certain pattern. The most mainstream uses of mouse gestures in computer software are for web browsers. (Chrome, Firefox, Opera, Internet Explorer)

Mouse gestures can provide an interesting game mechanic that you can add to your own programs (similar to what the Wiimote does in a few games).

You can download the module (and a simple Pygame test script that uses it) here:

MooseGestures & Test App (zipped)

moosegesture.py

moosegesturetest.py

Simon Gesture – A game that uses the MooseGesture module.

(The screenshot above shows the test app after entering a mouse gesture. It correctly identifies the gesture as Down Right Up.)

(The above screenshot shows a more complicated gesture: Down, Up, Down, Right, Left, Right.)
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Here’s a cipher disk that you can print and cutout to help you manually implement the Caesar Cipher. A program to implement this cipher (and break the cipher) is available in Chapter 14 of the free programming book “Invent Your Own Computer Games with Python” at http://inventwithpython.com/chapter14.html

Simply download and printout the PDF and cut out the two circles and place them on top of each other. The key number is whichever one is opposite the outer “A” letter.

Download the PDF

If you would like to change around the font or the logo, you can also download the original Photoshop file.

High resolution PNG files of the inner and outer circles are also available for download.