Python Lists – A Deep Dive with Examples

Updated on July 19, 2024

Article Outline

What is a List in Python?Characteristics of Lists Creating a List in Python Accessing Elements in the List Accessing elements from a multidimensional list Taking Input of a Python List Change List Items in the List Change List Items Using Slicing Add Elements to a Python List using the append() method Add Elements to a Python List using insert() method Add Elements to a Python List using the extend() method Reversing a List Remove an Item from a List.Iterating Through a List Get the Length of the List Built-in List functions Conclusion FAQs

Let’s dive into the world of Python lists, a versatile and widely used data structure. These lists are perfect for storing collections of items, even if they’re of different data types. In this article, we’ll explore the Python list, from its basic syntax to advanced operations, all with the help of illustrations.

What is a List in Python?

In Python programming, a list is a built-in data structure used to store collections of items. It is a mutable data structure. It means you can change the list’s contents after creation. Lists are defined by enclosing comma-separated values within square brackets ‘[]’.

Python List can contain different data types, including integers, floats, strings, boolean, and other lists.

Example of List

my_list = [1, 2, 3, 'hello', True, 5.6]

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Characteristics of Lists

The following are the characteristics of Lists:

Ordered: List data structure to maintain the order of elements.
Mutable: List are mutable data structures. It means It can change the order of the list.
Allow Duplicates: List data structure allows duplicate data.

Creating a List in Python

In Python, creating a list is as simple as riding a motorbike. We can create a list by passing elements in square brackets separated by a comma.

The following program demonstrates “how we can create a simple list in Python.”

Program

# A list of three elements

ages = [35, 20, 21]

print(ages)

# Output: [19, 26, 29]

Output

[35, 20, 21]

Accessing Elements in the List

Python uses zero-based indexing, meaning the first element has an index of 0. We can access individual elements using their index values in a list. We can also use negative values to access the list in Python. Negative indexing starts at the end of the list. It means ‘-1’ accesses the last element of the list.

Program

my_list = [1, 2, 3, 'hello', True, 5.6]

print(my_list[0])   # Output: 1

print(my_list[-1])  # Output: 5.6

Output

1

5.6

Accessing elements from a multidimensional list

In Python, we can create a multidimensional list, which is a list within a list. In this section, we will access the multidimensional list by indexing.

Program

# Python program to demonstrate printing

# of complete multidimensional list

a = [[2, 4, 6, 8, 10], [3, 6, 9, 12, 15], [4, 8, 12, 16, 20],[10,20,30,40,50]]

print(a)

print(a[0])

print(a[1])

print(a[2])

Output

[[2, 4, 6, 8, 10], [3, 6, 9, 12, 15], [4, 8, 12, 16, 20], [10, 20, 30, 40, 50]]

[2, 4, 6, 8, 10]

[3, 6, 9, 12, 15]

[4, 8, 12, 16, 20]

Taking Input of a Python List

In Python, we can also take input from the user and store it as a string, integer, float, etc. However, in Python, the input is a string.

The following program demonstrates the Python list.

Program

string = input("Enter elements (Space-Separated): ")

lst = string.split()

print('The list is:', lst)

Output

Enter elements (Space-Separated): Rajj, Kumar, Harry, Potter

The list is: ['Raj,', 'Kumar,', 'Harry', ',', 'Potter']

Change List Items in the List

In Python programming, a List is a mutable data structure. This means we can change the list after it is created using various methods, such as direct assignment, slicing, and list methods.

Assignment

We can change the list using the assignment operator. First, select the list item using the index, then assign the new value to the list.

The following program demonstrates the assignment changes in the list.

Program

my_list = [1, 2, 3, 4, 5]

my_list[2] = 'three'

print(my_list)  # Output: [1, 2, 'three', 4, 5]

Output

[1, 2, 'three', 4, 5]

Change List Items Using Slicing

We can also use slicing to change the list. First, we have to define the specific range for updating the list. Then, we define a new list with new values and assign those values to the old list.

The following program demonstrates the slicing.

Program

my_list = [1, 2, 3, 4, 5]

print(my_list)

my_list[1:4] = [20, 30, 40]

print(my_list)

Output

my_list = [1, 2, 3, 4, 5]

my_list[1:4] = [20, 30, 40]

Add Elements to a Python List using the append() method

In Python programming, we can add the list using the append() method. The following program demonstrates the append() method example.

Program

my_list = [1, 2, 3]

another_list = [4, 5, 6]

my_list.append(another_list)

print(my_list)

Output

[1, 2, 3, [4, 5, 6]]

Also read: Data Structures and Algorithms in Python

Add Elements to a Python List using insert() method

Python append() method adds the item in the list at the end of the list. This is good but sometimes it does not fill our needs. There is one more method in Python language for inserting the element in the list at the specific position. The insert() method takes two arguments: the first one is position, and the second one is the value.

The following program demonstrates the Python list insert()method.

Program

# Python program to demonstrate

# Addition of elements in a List


# Creating a List

List = [1,2,3,4]

print("Initial List: ")

print(List)


List.insert(3, 12)

List.insert(0, 'Computer Program')

print("nList after performing Insert Operation: ")

print(List)

Program

Initial List:

[1, 2, 3, 4]

List after performing Insert Operation:

['Computer Program', 1, 2, 3, 12, 4]

Add Elements to a Python List using the extend() method

There is one more method in the Python list for adding the elements and adding two lists in Python. The extend() method is used for adding multiple lists in a single list. It adds the list at the end of the list.

The following program demonstrates the Python List extend() method.

Program

# Creating a List

List = [1, 2, 3, 4]

print("Initial List: ")

print(List)

List.extend([8, 'Harry', 'Potter', 'Hermoine'])

print("nList after performing Extend Operation: ")

print(List)

Output

Initial List:

[1, 2, 3, 4]

List after performing Extend Operation:

[1, 2, 3, 4, 8, 'Harry', 'Potter', 'Hermoine']

Reversing a List

We can reverse a whole list using the inbuilt method in Python language. There are many easy ways to do this task. However, we will use two methods for solving this problem: the reverse() method and the reversed() method.

Using the reverse() method: The following program demonstrates the reverse() method example in Python.

Program

# Reversing a list

mylist = [1, 2, 3, 4, 5, 6, 7,8,9,10]

mylist.reverse()

print(mylist)

Output

[10, 9, 8, 7, 6, 5, 4, 3, 2, 1]

Using the reversed() function: The reversed() function returns the reverse iterator, which can be converted to the list using a list() function.

Program

my_list = ["Taj Mahal", "Red Fort", "Blue Fort", "White Fort", "Sky blue fort"]

reversed_list = list(reversed(my_list))

print(reversed_list)

Output

my_list = ["Taj Mahal", "Red Fort", "Blue Fort", "White Fort", "Sky blue fort"]

reversed_list = list(reversed(my_list))

print(reversed_list)

Remove an Item from a List.

In Python, there are various ways to remove an item from the list, such as the remove() method, pop() method, del keyword, and clear() method.

Using the remove() method: The following program removes items from the list using the remove() method.

Program

my_list = [1, 2, 3]

another_list = [4, 5, 6]

print(another_list)

my_list.append(another_list)

my_list.remove(1)

print(my_list)

Output

[4, 5, 6]

[2, 3, [4, 5, 6]]

Using the pop() method: The following program removes items from the list using the pop() method.

Program

my_list = [1, 2, 3]

another_list = [4, 5, 6]

print(another_list)

my_list.append(another_list)

my_list.pop()

print(my_list)

Output

[4, 5, 6]

[1, 2, 3]

Using the del keyword: We can also remove an item from the list using the del keyword. The following program does this.

Program

thislist = ["pineapple", "banana shake", "cherry juice"]

del thislist[0]

print(thislist)

Output

['banana shake', 'cherry juice']

Using the clear() method: The clear() method removes all elements from the list. The following program demonstrates the clear() method.

Program

thislist = ["pineapple", "banana shake", "cherry juice"]

print(thislist)

thislist.clear()

print(thislist)

Output

['pineapple', 'banana shake', 'cherry juice']

[]

Iterating Through a List

In Python, we can iterate a list using a for loop. The following program demonstrates this list iterating.

Program

fruits = ['apple', 'banana', 'orange']


# iterate through the list

for fruit in fruits:

print(fruit)

Output

apple

banana

orange

Get the Length of the List

In Python, we can also get the length of the list using the len() function, which returns the length of the list as an integer.

The following program demonstrates the len() function in the list.

Program

my_list = [1, 2, 3, 4, 5,10,29,39,True, "work"]

length_of_list = len(my_list)

print("The length of the list is:", length_of_list)

Output

The length of the list is: 10

Built-in List functions

The Python language has several built-in methods for working with lists. The following table describes the most common method: the Python List method.

Method	Description
append(x)	This method adds elements to the list
pop()	This method removes elements from the list. By default, it removes them from the end of the list.
count()	This method returns the number of specified values.
remove()	This method removes the element from the list. It removes the first item from the list
reverse()	This method reverses the order of the list
sort()	This method sorts the list
insert()	This method adds the item in the list by specific position
clear()	This method removes all the elements from the list
copy()	copy of the list

Conclusion

In this article, we learned about the list data structure in the Python programming language. This is a mutable data structure in Python, which means we can change the items in the list. There are various approaches to adding items to the list and removing items from the list, which we mentioned in this article. Understanding the list of components is very important for Python developers. You can dive deep into Python by pursuing the Certificate Program in DevOps & Cloud Engineering.

FAQs

What is a list in Python?

A list is a mutable data structure that can store different types of values. It is a built-in type of data structure in the Python programming language.

How to create a list in Python?

We can create a list using brackets, passing the elements within brackets and separating them by commas. For example, [“harry”, 1,].

How to reverse a list in Python?

We can create a reverse list using the inbuilt defined method, the reverse() method. This method reverses the list.

Is a list mutable in Python?

Yes, a List is a mutable data structure in Python, which means we can modify the data

How can I merge two lists?

In Python, we can merge two or most lists using the ‘+’ operators. Another approach, the “extend()” method, is also available.

Updated on July 19, 2024

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