In this tutorial, we will learn Python Lists

Python lists are ordered, mutable collections of items enclosed in square brackets ([]). They can store heterogeneous data types, such as integers, floats, strings, and even other lists. Lists are a fundamental data structure in Python and are commonly used for storing and manipulating collections of related values.

Here’s an example of a list containing various data types:

my_list = [1, 2, 'three', 4.5, True]

You can access individual elements in a list using indexing. Python uses zero-based indexing, so the first element is at index 0. Here’s an example:

print(my_list[0]) # Output: 1
print(my_list[2]) # Output: ‘three’

You can also use negative indexing to access elements from the end of the list. The last element has an index of -1, the second-to-last has an index of -2, and so on:

print(my_list[-1])  # Output: True
print(my_list[-3])  # Output: 'three'

Lists in Python are mutable, which means you can modify them by assigning new values to specific indexes:

my_list[1] = 'two'
print(my_list)  # Output: [1, 'two', 'three', 4.5, True]

You can perform various operations on lists, such as adding elements, removing elements, slicing, concatenating, and more. Here are some common list operations:

# Adding elements to a list
my_list.append('four')      # Adds 'four' at the end
my_list.insert(2, 'middle')  # Inserts 'middle' at index 2

# Removing elements from a list
my_list.remove('three')     # Removes the first occurrence of 'three'
popped_item = my_list.pop() # Removes and returns the last element

# Slicing a list
sliced_list = my_list[1:4]   # Returns a new list containing elements from index 1 to 3 (exclusive)

# Concatenating lists
new_list = my_list + [5, 6, 7]  # Combines two lists

# Length of a list
length = len(my_list)       # Returns the number of elements in the list

These are just a few examples of what you can do with lists in Python. They are versatile and widely used, providing a convenient way to work with collections of items.

Accessing elements from list

To access elements from a list in Python, you can use indexing or slicing. Here are a few examples:

1. Indexing: You can access a specific element at a given index using square brackets []. Indexing starts from 0 for the first element.

my_list = [10, 20, 30, 40, 50]
print(my_list[0])  # Output: 10
print(my_list[2])  # Output: 30

2. Negative Indexing: You can also use negative indexing to access elements from the end of the list. -1 refers to the last element, -2 refers to the second-to-last element, and so on.

my_list = [10, 20, 30, 40, 50]
print(my_list[-1])  # Output: 50
print(my_list[-3])  # Output: 30

3. Slicing: You can retrieve a portion of the list using slicing. Slicing allows you to specify a range of indices to extract a sublist. The range is specified using the syntax [start:end], where start is the index of the first element (inclusive), and end is the index of the last element (exclusive).

my_list = [10, 20, 30, 40, 50]
print(my_list[1:4])  # Output: [20, 30, 40]
print(my_list[:3])   # Output: [10, 20, 30]
print(my_list[2:])   # Output: [30, 40, 50]

You can also specify a step value in the slice using [start:end:step]. This allows you to skip elements in the sublist.

my_list = [10, 20, 30, 40, 50]
print(my_list[::2])  # Output: [10, 30, 50]

These are some basic techniques for accessing elements from a list in Python. Remember that lists are mutable, so you can modify their elements using indexing and slicing as well.