Python Lists and Tuples Cheat Sheet

Python most versatile and useful data types are lists and tuples. They can be found in almost every Python program that isn’t trivial.

This cheat sheet will teach you the following: You’ll learn about the key differences between lists and tuples. You’ll discover how to define them and manipulate them. You should have a good sense of when and how to use these object types in a Python program once you’ve completed.

Python Lists Data Type

In a nutshell, a list is a collection of arbitrary items that functions similarly to an array in many other programming languages but is more versatile. In Python, we create lists by enclosing a comma-separated list of objects in square brackets ([]), as illustrated below:

The following are some of the most essential aspects of Python lists:

• Lists are ordered.
• Lists can contain any arbitrary objects.
• Indexing is used to access list elements.
• We can nest lists to arbitrary depths.
• Lists are mutable.
• Lists are dynamic.

['cat', 'bat', 'rat', 'elephant']

Getting Individual Values in a List with Indexes

spam = ['cat', 'bat', 'rat', 'elephant']
spam[0]

spam[1]

spam[2]

spam[3]

Negative Indexes

spam = ['cat', 'bat', 'rat', 'elephant']
spam[-1]

spam[-3]

'The {} is afraid of the {}.'.format(spam[-1], spam[-3])

Getting Sublists with Slices

spam = ['cat', 'bat', 'rat', 'elephant']
spam[0:4]

spam[1:3]

spam[0:-1]

spam = ['cat', 'bat', 'rat', 'elephant']
spam[:2]

spam[1:]

spam[:]

Getting a list Length with len

spam = ['cat', 'dog', 'moose']
len(spam)

Changing Values in a List with Indexes

spam = ['cat', 'bat', 'rat', 'elephant']
spam[1] = 'aardvark'
spam

spam[2] = spam[1]
spam

spam[-1] = 12345
spam

List Concatenation and List Replication

[1, 2, 3] + ['A', 'B', 'C']

['X', 'Y', 'Z'] * 3

spam = [1, 2, 3]
spam = spam + ['A', 'B', 'C']
spam

Removing Values from Lists with del Statements

spam = ['cat', 'bat', 'rat', 'elephant']
del spam[2]
spam

del spam[2]
spam

Using for Loops with Lists

supplies = ['pens', 'staplers', 'flame-throwers', 'binders']

for i, supply in enumerate(supplies):
    print('Index {} in supplies is: {}'.format(str(i), supply))

Looping Through Multiple Lists with zip

name = ['Pete', 'John', 'Elizabeth']
age = [6, 23, 44]

for n, a in zip(name, age):
    print('{} is {} years old'.format(n, a))

The in and not in Operators

'howdy' in ['hello', 'hi', 'howdy', 'heyas']

spam = ['hello', 'hi', 'howdy', 'heyas']
False

'howdy' not in spam

'cat' not in spam

The Multiple Assignment Trick

The multiple assignment trick is a code shortcut that allows you to assign many variables to a list of values in a single line. As a result, instead of performing this:

cat = ['fat', 'orange', 'loud']
size = cat[0]
color = cat[1]
disposition = cat[2]

You could type this line of code:

cat = ['fat', 'orange', 'loud']
size, color, disposition = cat

We use the multiple assignment trick to swap the values in two variables:

a, b = 'Alice', 'Bob'
a, b = b, a
print(a)

print(b)

Augmented Assignment Operators

Examples:

spam = 'Hello'
spam += ' world!'
spam

bacon = ['Zophie']
bacon *= 3
bacon

Finding a Value in a List with the index Method

spam = ['Zophie', 'Pooka', 'Fat-tail', 'Pooka']
spam.index('Pooka')

Adding Values to Lists with append and insert

append():

spam = ['cat', 'dog', 'bat']
spam.append('moose')
spam

insert():

spam = ['cat', 'dog', 'bat']
spam.insert(1, 'chicken')
spam

Removing Values from Lists with remove

spam = ['cat', 'bat', 'rat', 'elephant']
spam.remove('bat')
spam

If a value appears in the list more than once, just the first instance will be eliminated.

Sorting the Values in a List with sort

spam = [2, 5, 3.14, 1, -7]
spam.sort()
spam

spam = ['ants', 'cats', 'dogs', 'badgers', 'elephants']
spam.sort()
spam

To have sort() sort the values in reverse order, you can provide the reverse keyword argument:

spam.sort(reverse=True)
spam

If you want to sort the items in alphabetical order, use the key keyword parameter str. lower in the sort() method call:

spam = ['a', 'z', 'A', 'Z']
spam.sort(key=str.lower)
spam

To create a new list, use the built-in function sorted:

spam = ['ants', 'cats', 'dogs', 'badgers', 'elephants']
sorted(spam)

Python Tuple Data Type

A tuple is a Python type that represents an ordered collection of things.

Tuples are similar to lists in every way except for the features listed below:

• Tuples are defined by enclosing the elements in parentheses (()) instead of square brackets ([]).
• Tuples are immutable.

eggs = ('hello', 42, 0.5)
eggs[0]

eggs[1:3]

len(eggs)

The fundamental difference between tuples and lists is that tuples, like strings, are immutable.

Converting Types with the list and tuple Functions

tuple(['cat', 'dog', 5])

list(('cat', 'dog', 5))

list('hello')

Conclusion

Understanding the differences between Python lists and tuples is crucial for effective data handling in your programs. Lists offer flexibility with mutable data and various manipulation methods, while tuples provide a fixed, immutable structure for storing ordered collections. By mastering these data types and their associated operations, you can enhance your Python programming skills and write more efficient, reliable code.

Happy Coding…!!!