Table Of ContentTreading on Python Series
Illustrated Guide to Python 3
A Complete Walkthrough of Beginning Python with Unique
Illustrations Showing how Python Really Works
Matt Harrison
Technical Editors: Roger A. Davidson, Andrew McLaughlin
Version: Oct 2, 2017
Copyright © 2017
While every precaution has been taken in the preparation of this book, the
publisher and author assumes no responsibility for errors or omissions, or for
damages resulting from the use of the information contained herein.
Table of Contents
Introduction
Why Python?
Which Version of Python?
The Interpreter
Running Programs
Writing and Reading Data
Variables
More about Objects
Numbers
Strings
dir, help, and pdb
Strings and Methods
Comments, Booleans, and None
Conditionals and Whitespace
Containers: Lists, Tuples, and Sets
Iteration
Dictionaries
Functions
Indexing and Slicing
File Input and Output
Unicode
Classes
Subclassing a Class
Exceptions
Importing Libraries
Libraries: Packages and Modules
A Complete Example
Onto Bigger and Better
File Navigation
Useful Links
About the Author
Also Available
One more thing
Introduction
ARE YOU READY TO JUMPSTART YOUR PYTHON PROGRAMMING CAREER? THIS BOOK WILL
arm you with years of knowledge and experience that are condensed into an easy
to follow format. Rather than taking months reading blogs, websites, and
searching mailing lists and groups, this book will allow a programmer to quickly
become knowledgeable and comfortable with Python.
Programming is fun and Python makes it delightful. Basic Python is not only
easy, but approachable for all ages. I have taught elementary students, teenagers,
“industry” professionals and “golden years” folks the Python programming
language. If you are willing to read and type, you are about to begin an exciting
path. Where it ultimately takes you depends on how hard you are willing to
work.
There are different levels of Python. Basic Python syntax is small and easy to
learn. Once you master basic Python, doors will open to you. You should be able
to read a lot of Python and understand it. From there, you can learn more
advanced topics, specific toolkits, start contributing to open source projects
written in Python, or use that knowledge to learn other programming languages.
A recommended approach for learning the language is to read a chapter and
then sit down at a computer and type out some of the examples found in the
chapter. Python makes it easy to get started, eliminating much of the hassle
found in running programs in other languages. The temptation will likely be to
merely read the book. By jumping in and actually typing the examples you will
learn a lot more than by just reading.
Why Python?
PYTHON IS BOOMING! IT IS THE TOP LANGUAGE BEING TAUGHT IN UNIVERSITIES. PYTHON
developers are among the highest paid. With the boom in data science, Python is
quickly becoming one of the most desired skills for analytics. Operations are
also adopting Python to manage their backend systems. They are discovering
what web developers using Python have known for a long time; namely, that
Python will make you productive.
Python has crossed the tipping point. No longer are only small, agile startups
relying on it. Looking to take advantage of its power and efficiency, enterprises
have also converged on Python. Over the past year, I've taught Python to
hundreds of seasoned developers with years of experience at large companies,
who are moving to Python.
Python enables increased productivity. I came to Python as a Perl
programmer. At work, I was assigned to a team with a co-worker who was well
versed in Tcl. Neither of us wanted to jump ship though both of us were
interested in learning Python. In 3 days our prototype was completed, much
faster than we expected, and we both promptly forgot our previous “goto”
language. What appealed to me about Python was that it fit my brain. I firmly
believe if you have some experience in programming, you can learn the basics of
Python in a few days.
Python is easy to learn. For beginning programmers, Python is a great
stepping stone. Learning to write simple programs is pretty easy, yet Python also
scales up to complex “enterprise” systems. Python also scales with age—I have
personally seen people from 7-80+ learn basic programming skills using Python.
Which Version of Python?
THIS BOOK WILL FOCUS ON PYTHON 3. PYTHON 2 HAS SERVED US WELL OVER THE
years. The Python Software Foundation, which manages releases of the
language, has stated that Python 2 is coming to an end. As such, after 2020 they
will no longer support the language.
Python 3, has been out for a bit now and is somewhat backward incompatible
with the 2 series. For green field development, you should move forward with
Python 3. If you have legacy systems on Python 2, do not fret. In fact, most of
the content in this book is perfectly applicable to Python 2. If you want to focus
on Python 2, check out the prior version of this book.
Python installation
Python 3 is not installed on most platforms. Some Linux distributions ship with
it, but Windows and Mac users will need to install it.
1
For Windows folks, go to the download area of the Python website and find a
link that says “Python 3.6 Windows Installer”. This will link to a .msi file that
will install Python on your Windows machine. Download the file, open it by
double-clicking it, and follow the instructions to finish the installation.
NOTE
On the Windows installer there is an option labeled "Add Python to
PATH". Please make sure it is checked. That way, when you run python
from the command prompt, it will know where to find the Python
executable. Otherwise, you can go to System properties (click WIN+Pause,
or run environ from the start menu), Advanced system settings, and click
on the Environment Variables button. There you can update the PATH
variable by adding the following:
C:\Program Files\Python 3.6;C:\Program Files\Python 3.6\Scripts
If you have UAC (User Account Control) enabled on Windows, then
path is:
C:\Users\<username>\AppData\Local\Programs\Python\Python36
Likewise, Mac users should download the Mac installer from the Python
website.
NOTE
2
Another option for installing Python is to use the Anaconda distribution.
This runs on Windows, Mac, and Linux, and also provides many pre-built
binaries for doing scientific calculations. Traditionally, these libraries have
been annoying to install as they wrap libraries written in C and Fortran, that
require some setup for compiling.
3
Mac users might also want to look into the Homebrew version . If you
are already familiar with Homebrew, it is a simple brew install python3
away.
Which editor?
In addition to installing Python, you will need a text editor. An editor is a tool
for writing code. A skilled craftsman will invest the time to learn to use their tool
appropriately and it will pay dividends. Learning to use the features of an editor
can make churning out code easier. Many modern editors today have some
semblance of support for Python.
If you are just beginning with Python and have not had much experience with
real text editors, most Python installations include IDLE, which has decent
Python editing features. The IDLE development environment also runs on
Windows, Mac and Linux.
4
A feature to look for in editors is integration with the Python REPL . Later
you will see an example with IDLE. Hopefully your editor of choice will have
similar features.
Popular editors with decent Python support include Emacs, Vim, Atom,
Visual Studio Code, and Sublime Text. If you are interested in more fancy
editors that have support for refactoring tools and intelligent completion,
PyCharm and Wing IDE are also popular.
Summary
Python 3 is the current version of Python. Unless you are working on legacy
code, you should favor using this version. You can find the latest version on the
Python website.
Most modern editors contain some support for Python. There are various
levels of features that editors and IDEs provide. If you are getting started
programming, give the IDLE editor a try. It is a great place to start out.
Exercises
1. Install Python 3 on your computer. Make sure you can start Python.
2. If you are used to a particular editor, do some investigation into its support
for Python. For example, does it:
Do syntax highlighting of Python code?
Run Python code in a REPL for you?
Provide a debugger for stepping through your Python code?
1 - https://www.python.org/download
2 - https://www.anaconda.com/download/
3 - https://brew.sh/
4 - REPL stands for Read, Evaluate, Print, and Loop. You will soon see an
example using it.
