H a n d s o n, p r o j e c t b a s e d

try it yourself
2-11. Zen of Python:
Enter import this into a Python terminal session and skim 
through the additional principles.

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32
Chapter 2
Summary
In this chapter you learned to work with variables. You learned to use descrip-
tive variable names and how to resolve name errors and syntax errors when 
they arise. You learned what strings are and how to display strings using lower-
case, uppercase, and title case. You started using whitespace to organize out-
put neatly, and you learned to strip unneeded whitespace from different parts 
of a string. You started working with integers and floats, and learned some of 
the ways you can work with numerical data. You also learned to write explana-
tory comments to make your code easier for you and others to read. Finally, 
you read about the philosophy of keeping your code as simple as possible, 
whenever possible.
In Chapter 3 you’ll learn to store collections of information in data 
structures called lists. You’ll learn to work through a list, manipulating any 
information in that list.

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3
I n t r o d u c I n g L I s t s
In this chapter and the next you’ll learn 
what lists are and how to start working with 
the elements in a list. Lists allow you to store 
sets of information in one place, whether you 
have just a few items or millions of items. Lists are 
one of Python’s most powerful features readily acces-
sible to new programmers, and they tie together many 
important concepts in programming.
What Is a List?
A list is a collection of items in a particular order. You can make a list that 
includes the letters of the alphabet, the digits from 0–9, or the names of 
all the people in your family. You can put anything you want into a list, and 

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34
Chapter 3
the items in your list don’t have to be related in any particular way. Because 
a list usually contains more than one element, it’s a good idea to make the 
name of your list plural, such as 
letters
, 
digits
, or 
names
. 
In Python, square brackets (
[]
) indicate a list, and individual elements 
in the list are separated by commas. Here’s a simple example of a list that 
contains a few kinds of bicycles:
 bicycles.py bicycles = ['trek', 'cannondale', 'redline', 'specialized']
print(bicycles)
If you ask Python to print a list, Python returns its representation of the 
list, including the square brackets:
['trek', 'cannondale', 'redline', 'specialized'] 
Because this isn’t the output you want your users to see, let’s learn how 
to access the individual items in a list.