Lists

Lists are among Python’s most valuable and frequently used data types, and they are the heart of countless programs. So, what exactly is a list, and why are they so indispensable?

In essence, a list is a dynamic and mutable sequence of values. Think of it as a versatile bag storing various items—numbers, words, and even a medley of data types—all within a single container. This flexibility makes lists an invaluable asset for any Python programmer.

Tip

Closely related to lists are tuples, which are immutable, but can be managed with similar syntax.

Let’s explore the concept further with a real-world analogy. Imagine you have a collection of names, distances, and mixed data types like this:

users = ["Jim", "Dwight", "Michael"]
distance_in_kms = [32, 97, 51, 403, 21, 53, 81]
mixed_types = ["Jim", 23, 3.14, True, "Berzerk"]

In this example, users contains a list of names of string types, distance_in_kms stores a list of distances in int type, and mixed_types seemingly defies convention by accommodating a diverse set of data types. Lists are compelling because they allow you to organize and manipulate such data effortlessly.

Accessing List Items

List items can be accessed via their index system like this:

users = ["Jim", "Dwight", "Michael"]
print(f"What is your favourite moment when {users[0]} pulls a prank on {users[1]}?")

Returns:

What is your favourite moment when Jim pulls a prank on Dwight?

Lists can even be accessed through negative indexing like this:

users = ["Jim", "Dwight", "Michael"]
print(f"What was one thing that {users[-1]} did you found extra funny?")

Outputs:

What was one thing that Michael did you found extra funny?

Adding and Removing Items from Lists

What makes lists genuinely exceptional is their mutability. Unlike some data types in Python, lists can change and adapt as your program runs. Adding, removing, or modifying elements within a list makes it a dynamic tool for handling evolving data. This adaptability is particularly useful when managing data collections that may grow or shrink in size.

users = ["Jim", "Dwight", "Michael"]
users.append("Pam")
print(f"We've added {users[-1]} to the list!")

Results in:

We've added Pam to the list!