In Python, a list is one of the most versatile and commonly used data structures. Lists are ordered, mutable, and capable of storing mixed data types. Whether you’re just getting started with Python or brushing up your knowledge, mastering lists is essential.
This blog post introduces you to 15 beginner-friendly exercises on lists, along with a detailed breakdown of list mutators and built-in methods—explaining how each one works with simple examples.
What is a List Mutator?
Mutators are operations that change the contents of a list. For example, adding, removing, or reordering elements.
Common List Mutators and Built-in Methods
| Method | Description | Example |
|---|---|---|
append(item) | Adds item to the end of the list | mylist.append(10) |
insert(index, item) | Inserts item at the given index | mylist.insert(1, 'apple') |
remove(item) | Removes the first occurrence of item | mylist.remove('apple') |
pop(index) | Removes and returns item at index (default is last) | mylist.pop() |
clear() | Removes all items from the list | mylist.clear() |
sort() | Sorts the list in ascending order | mylist.sort() |
reverse() | Reverses the list in place | mylist.reverse() |
index(item) | Returns index of first occurrence of item | mylist.index('cat') |
count(item) | Returns the number of times item appears | mylist.count(3) |
extend(iterable) | Adds elements of another iterable (e.g., list) | mylist.extend([4, 5]) |
Note: All these methods (except index() and count()) mutate the list.
# Create a List of Integers
# Task: Create a list of integers from 1 to 10 and print it.
integers_list = []
for i in range(1, 11):
integers_list.append(i)
print(integers_list)
# output
# [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
# Access Elements by Index
# Task: Print the first, middle, and last element from the list colors = ['red', 'green', 'blue', 'yellow', 'purple'].
colors = ['red', 'green', 'blue', 'yellow', 'purple']
print(f'First Element: {colors[0]}')
print(f'Middle Element: {colors[len(colors)//2]}')
print(f'Last Element: {colors[-1]}')
# output
# First Element: red
# Middle Element: blue
# Last Element: purple
# Traverse a List with a Loop
# Task: Print each element in the list animals = ['dog', 'cat', 'rabbit'] using a for loop.
animals = ['dog', 'cat', 'rabbit']
for animal in animals:
print(animal)
# output
# dog
# cat
# rabbit
# Sum of List Elements
# Task: Given a list numbers = [5, 10, 15, 20], find the total sum using a loop.
numbers = [5, 10, 15, 20]
sum_numbers = sum(numbers)
print(sum_numbers)
# output
# 50
# Find Maximum and Minimum Values
# Task: Use max() and min() to find the largest and smallest numbers in values = [3, 8, 1, 9, 12].
values = [3, 8, 1, 9, 12]
print(f'Max: {max(values)}')
print(f'Min: {min(values)}')
# output
# Max: 12
# Min: 1
# Append and Remove Items
# Task: Given fruits = ['apple', 'banana'], append 'orange' and remove 'banana'.
fruits = ['apple', 'banana']
fruits.append('orange')
fruits.remove('banana')
print(fruits)
# output
# ['apple', 'orange']
# Check if Item Exists
# Task: Ask the user to enter a fruit name.
# If the fruit exists in ['apple', 'mango', 'grape'], print "Available", else "Not Available".
fruit = ['apple', 'mango', 'grape']
user_fruit = input("Enter a fruit name: ")
if user_fruit in fruit:
print('Available')
else:
print('Not Available')
# output
# Enter a fruit name: mango
# Available
# Enter a fruit name: banana
# Not Available
# Count Occurrences
# Task: Count how many times 3 appears in the list data = [1, 3, 3, 5, 3, 7].
data = [1, 3, 3, 5, 3, 7]
print(data.count(3))
# output
# 3
# Sort a List
# Task: Sort the list scores = [85, 72, 90, 60] in ascending and descending order.
scores = [85, 72, 90, 60]
ascending = sorted(scores)
descending = sorted(scores, reverse=True)
print(f'ascending: {ascending}')
print(f'descending: {descending}')
# output
# ascending: [60, 72, 85, 90]
# descending: [90, 85, 72, 60]
# Reverse a List
# Task: Reverse the list cities = ['London', 'Paris', 'Tokyo'] using the reverse() method.
cities = ['London', 'Paris', 'Tokyo']
reverse_cities = cities[::-1]
print(reverse_cities)
# output
# ['Tokyo', 'Paris', 'London']
# Concatenate Two Lists
# Task: Combine list1 = [1, 2, 3] and list2 = [4, 5] into one list and print it.
list1 = [1, 2, 3]
list2 = [4, 5]
concatenated_list = list1 + list2
print(concatenated_list)
# output
# [1, 2, 3, 4, 5]
# Replace an Item
# Task: Change the second item in names = ['Alice', 'Bob', 'Charlie'] to 'Ben'.
names = ['Alice', 'Bob', 'Charlie']
names[1] = 'Ben'
print(names)
# output
# ['Alice', 'Ben', 'Charlie']
# Find Index of an Item
# Task: Use the index() method to find the position of 'cat' in animals = ['dog', 'cat', 'mouse'].
animals = ['dog', 'cat', 'mouse']
print(animals.index('cat'))
# output
# 1
# Insert Item at Position
# Task: Insert 'grape' at the second position in the list fruits = ['apple', 'banana'].
fruits = ['apple', 'banana']
fruits.insert(1, 'grape')
print(fruits)
# output
# ['apple', 'grape', 'banana']
# Remove Duplicates
# Task: Given nums = [1, 2, 2, 3, 3, 3, 4], create a new list that contains only unique elements.
nums = [1, 2, 2, 3, 3, 3, 4]
unique_nums = []
for num in nums:
if num not in unique_nums:
unique_nums.append(num)
print(unique_nums)
# output
# [1, 2, 3, 4]
Bonus: List Slicing Works Like String Slicing
Just like strings, Python lists support slicing, which allows you to access a range of elements using the list[start:stop:step] syntax.
Syntax Recap:
list[start:stop:step]
start: Index to begin slicing (inclusive)stop: Index to stop slicing (exclusive)step: Interval between elements (optional)
Examples:
numbers = [10, 20, 30, 40, 50, 60, 70]
| Slice | Result | Description |
|---|---|---|
| numbers[1:4] | [20, 30, 40] | Elements from index 1 to 3 |
| numbers[:3] | [10, 20, 30] | First 3 elements |
| numbers[3:] | [40, 50, 60, 70] | From index 3 to end |
| numbers[::2] | [10, 30, 50, 70] | Every second element |
| numbers[::-1] | [70, 60, 50, 40, 30, 20, 10] | Reversed list |
Why Use Slicing?
- Quickly extract a sublist
- Reverse a list
- Skip elements with steps
- Copy a list:
copied = original[:]
Pro Tip:
List slicing returns a new list and does not modify the original.
original = [1, 2, 3, 4]
copy = original[:]
print(copy) # [1, 2, 3, 4]
print(original) # [1, 2, 3, 4]
