LIST
A list is a versatile and mutable data structure that allows you to store a collection of items. Lists are defined by enclosing the elements in square brackets [ ] and separating them with commas. Lists can contain elements of different data types, and you can change, add, or remove elements after the list is created.
my_list = [1, 2, 3, 'hello', True]
Creating a List
# Empty list
empty_list = []
# List with elements
fruits = ['apple', 'banana', 'orange']
# Mixed data types in a list
mixed_list = [1, 'hello', 3.14, True]
Accessing Elements:
You can access individual elements in a list using indexing. Python uses zero-based indexing, so the first element is at index 0.
fruits = ['apple', 'banana', 'orange']
first_fruit = fruits[0]
second_fruit = fruits[1]
print("First Fruit:", first_fruit)
print("Second Fruit:", second_fruit)
Slicing Lists:
You can also create sublists using slicing.
numbers = [1, 2, 3, 4, 5]
subset = numbers[1:4] # Elements at index 1, 2, 3
print("Subset:", subset)
Modifying Lists:
fruits = ['apple', 'banana', 'orange']
# Changing an element
fruits[1] = 'grape'
# Adding elements
fruits.append('kiwi') # Adds 'kiwi' to the end of the list
fruits.insert(1, 'pear') # Inserts 'pear' at index 1
# Removing elements
removed_fruit = fruits.pop(2) # Removes and returns the element at index 2
fruits.remove('apple') # Removes the first occurrence of 'apple'
print("Modified Fruits:", fruits)
print("Removed Fruit:", removed_fruit)
List Operations
# Concatenation
list1 = [1, 2, 3]
list2 = ['a', 'b', 'c']
combined_list = list1 + list2
# Repetition
repeated_list = list1 * 3
print("Concatenated List:", combined_list)
print("Repeated List:", repeated_list)
Common List Methods
numbers = [3, 1, 4, 1, 5, 9, 2]
# Sorting
numbers.sort()
# Reversing
numbers.reverse()
# Length of the list
length = len(numbers)
# Finding index of an element
index_of_5 = numbers.index(5)
print("Sorted Numbers:", numbers)
print("Length of the List:", length)
print("Index of 5:", index_of_5)