What are Lists in Python?

Imagine having a magical container that can hold a multitude of items in a specific order. That’s precisely what Python lists are! In simple terms, a list is an ordered collection of elements, allowing you to store different types of data, such as numbers, names, or even other lists, all in one place. This incredible flexibility makes lists an essential tool in your Python toolkit.

So, get ready yourself to unlock the full potential of this versatile data type that will empower you to organize and manipulate your data like a pro. In this tutorial, we will take you on a step-by-step journey, providing clear instructions and practical examples to help you master the art of Python lists. Whether you’re a beginner or already have some experience, we’ve got you covered. So, grab your coding hat and let’s embark on this exciting adventure together!

Python List syntax

Python lists are denoted by enclosing the elements within square brackets [ ]. Elements within the list are separated by commas. Let’s dive into an example to illustrate this:

favorite_destinations = ['Bali', 'Paris', 'Hawaii', 'Maldives']

In this example, we have created a list called favorite_destinations that contains popular travel spots. Each destination is represented as a string, enclosed in quotes, and separated by commas. Now, let’s unravel the secrets of manipulating these captivating lists!

What is list() function in Python?

Creating lists is an exciting endeavor, and Python offers a handy function called list() to help us on our journey. This function allows you to convert an iterable object, such as a string or a tuple, into a list. Let’s explore an example using a list of popular celebrities:

celebrities = list(('Brad Pitt', 'Angelina Jolie', 'Leonardo DiCaprio', 'Jennifer Aniston'))

In this example, we utilize the list() function to convert a tuple of celebrity names into a list. Now, we’re armed with a powerful tool to create captivating lists in Python!

How to create Python list?

Creating a list from scratch is a breeze in Python. Simply enclose the elements within square brackets [ ], separated by commas. Let’s create a list of favorite fruits to illustrate this:

favorite_fruits = ['apple', 'banana', 'orange', 'strawberry']

In this example, we have crafted a delightful list of our favorite fruits. Each fruit name is a string, enclosed in quotes, and separated by commas. The possibilities for list creation are endless!

I. Accessing List Elements

Once you’ve created a list, you’ll want to access and retrieve specific elements. Python provides a simple indexing mechanism to access individual elements within a list. Let’s say we want to retrieve the second element from our favorite_fruits list:

In this example, we access the second element of the list using the index 1 (remember, Python uses zero-based indexing). We then print a friendly message incorporating the retrieved fruit. The world of list access is at our fingertips!

II. Modifying List Elements

Lists are not static entities; they are dynamic and mutable. This means we can modify the elements within a list to reflect changes in our data. Let’s see how we can update the favorite_fruits list:

In this example, we update the first element of the list to reflect a change in our taste. We then print a message displaying the modified list. Lists grant us the power to adapt and evolve!

Python provides several useful methods to modify list elements based on specific requirements. Let’s explore a couple of them:

III. Adding Elements to the End – using append()

The append() method allows you to add new elements to the end of a list. Let’s consider an example where we have a list of fruits:

In this example, we use fruits.append('grape') to add the fruit ‘grape’ to the end of the fruits list. The append() method modifies the original list by adding the specified element to the end.

IV. Inserting Elements at a Specific Position

The insert() method allows you to insert a new element at a specific position in a list. Let’s see an example where we have a list of numbers:

In this example, we use numbers.insert(2, 10) to insert the number 10 at index 2 of the numbers list. The insert() method shifts the existing elements to the right and adds the new element at the specified position.

Sorting Python List Elements

Python Sorting allows us to organize our data in a particular order, making it easier to analyze, search, and manipulate. Python provides several methods to sort lists, each offering different functionalities. So, let’s explore the art of sorting in Python!

I. Sorting a List in Ascending Order

To sort a list in ascending order, we can use the sort() method. Let’s consider an example where we have a list of numbers:

For this example, we use the sort() method to sort the numbers list in ascending order. The sort() method modifies the original list, rearranging the elements in ascending order. After sorting, we print the updated list to display the sorted result.

II. Sorting a List in Descending Order

If we want to sort a list in descending order, we can utilize the sort() method with the reverse parameter. Let’s modify our previous example to sort the list in descending order:

In this example, we use the sorted() function to sort the names list without modifying the original list. The sorted() function returns a new sorted list, leaving the original list intact. We assign the sorted list to the sorted_names variable and print the result.

IV. Custom Sorting with the key Parameter

Python allows us to perform custom sorting by providing a key function that determines the sorting criteria. Let’s consider an example where we have a list of names, and we want to sort them based on their lengths:

In this example, we pass the key=len argument to the sorted() function. This instructs Python to sort the names list based on the length of each name. The len function serves as the key function, determining the sorting criteria. The result is a sorted list based on name lengths.

Till here, You have explored various ways to create, access, modify and sort list elements. Now, let’s explore how to remove items from a list.

In this example, we use del favorite_books[2] to remove the book at index 2 from the favorite_books list. The del statement modifies the original list by deleting the specified item. After removing the book, we print the updated list to confirm the change.

II. Removing List Items by Value

Sometimes, you may want to remove an item from a list based on its value rather than its index. Python provides the remove() method to accomplish this task. Let’s take a look at an example where we have a list of favorite movies:

In this example, we use favorite_movies.remove('Inception') to remove the movie ‘Inception’ from the favorite_movies list. The remove() method searches for the specified value in the list and removes the first occurrence of it. Again, we print the updated list to verify the change.

III. Clearing the Entire List

If you want to remove all items from a list and start fresh, Python provides the clear() method. Let’s see an example:

In this example, we use shopping_list.clear() to remove all items from the shopping_list. The clear() method empties the list, leaving it with no elements. We then print the list to confirm that it is now empty.

favorite_colors = ['blue', 'red', 'green', 'yellow']

In this example, we use the + operator to concatenate list1 and list2. The + operator combines the elements of both lists, creating a new list called concatenated_list. The resulting list contains all the elements from list1 followed by all the elements from list2.

Above , we use the extend() method on list1 and pass list2 as an argument. The extend() method adds the elements of list2 to the end of list1, effectively concatenating the two lists. The original list1 is modified, and the result is displayed below:

Python Nested Lists: Lists within Lists

In our exploration of Python lists, we’ve covered various aspects of working with single-dimensional lists. Now, let’s take a dive into the Python nested lists. A nested list is a list that contains other lists as its elements. This powerful concept allows us to create complex data structures, representing multidimensional data and hierarchical relationships. So, let’s unravel the potential of nested lists!

I. Creating Nested Lists

To create a nested list, we simply include lists as elements within another list. Let’s consider an example where we have a nested list representing a matrix:

matrix = [[1, 2, 3],
[4, 5, 6],
[7, 8, 9]]

In this example, we access the element at row 1 and column 2 of the matrix using matrix[1][2]. The first index 1 refers to the second inner list row 1, and the second index 2 refers to the third element within that inner list column 2. By specifying multiple indices, we can retrieve specific elements within the nested list structure.

III. Modifying Elements in Nested Lists

Modifying elements in nested lists follows a similar approach to accessing elements. We use multiple indices to navigate and update specific elements. Let’s modify an element in our matrix example:

In this example, we modify the element at row 0 and column 1 of the matrix by assigning the value 10 to matrix[0][1]. By specifying the indices, we can navigate to the desired element and update its value. The resulting matrix reflects the modification we made.