Difference Between List, Tuple, Set and Dictionary in Python

We are going to create these various collections data types in Python and also outline the differences between them. Find the Video Lesson here

1. Python List

A list in python is a collection of various items which may be either of the same or of different data types. The items in a list are separated by commas and enclosed in square braces. Listing 1.0 shows how to create a list in python

assets = ["Computer", "Printer", "TV", "Camera"]

scores = [56, 45.9, 89.5, 70, 32.9, 67.4]

letters = ['k', 'i', 'n', 'd', 's', 'o', 'n']

things = ["chair", 45, 'A', "house"]

Listing 1.0: Examples of Lists in Python

2. Python Tuple

A tuple in python is also a collection of items just like list. Take note of the two key difference:

A tuple is immutable (you can’t change the elements once created)
A tuple is created with rounded braces

Listing 1.1 show example of Tuple

assets = ("Computer", "Printer", "TV", "Camera")

scores = (56, 45.9, 89.5, 70, 32.9, 67.4)

letters = ('k', 'i', 'n', 'd', 's', 'o', 'n')

things = ("chair", 45, 'A', "house")

Listing 1.1: Example of Tuple in Python

3. Python Dictionary

A dictionary in python is a collections of key-value pairs of item. For each entry, there are two items: a key and a value. Note the following about Python dictionaries

keys in a dictionary must be unique (no two same keys)
keys are immutable
keys and values can be of any data types
the keys() function returns list of keys in a dictionary
the values() function returns list of values in dictionary

Example of dictionaries are given in Listing 1.3.

months = {
    "Jan": "January",
    "Feb": "Febraury",
    "Mar": "March",
    "Apr": "April",
    "May": "May",
    "Jun": "June",
    "Jul": "July",
    "Aug": "August",
    "Sep": "September"
}

weekdays = {
    1: "Monday",
    2: "Tuesday",
    3: "Wednesday",
    4: "Thursday",
    5: "Friday",
    6: "Saturday",
    7: "Sunday"
}

Listing 1.2: Examples of Dictionaries in Python

4. Python Set

A set in python is a collection of items just like Lists and Tuples. Note the following about sets:

A set is created using the set keyword
A set cannot be an element of a set (but a list can be an element of a list)

Also note: As pointed out by Luka Jeličić Lux, Sets cannot have same element multiple times. Example: When you have set([1,2,2,2,3,3,4,4,5,5]) and print it you get [1,2,3,4,5] as output.

Examples of sets is given in Listing 1.3

assets = set(["Computer", "Printer", "TV", "Camera"])

scores = set([56, 45.9, 89.5, 70, 32.9, 67.4])

letters = set(['k', 'i', 'n', 'd', 's', 'o', 'n'])

things = set(["chair", 45, 'A', "house"])