Adding Items to a List

append() -- Add to the End

The append() method adds a single item to the end of a list.

fruits = ["apple", "banana"]
fruits.append("cherry")
print(fruits)

# You can append any data type
numbers = [1, 2, 3]
numbers.append(4)
print(numbers)

insert() -- Add at a Specific Position

The insert() method adds an item at a specific index. All items after that index shift to the right.

fruits = ["apple", "cherry", "date"]
fruits.insert(1, "banana")   # Insert at index 1
print(fruits)

# Insert at the beginning
fruits.insert(0, "avocado")
print(fruits)

extend() -- Add Multiple Items

The extend() method adds all items from another list (or iterable) to the end.

fruits = ["apple", "banana"]
more_fruits = ["cherry", "date", "elderberry"]

fruits.extend(more_fruits)
print(fruits)

# append adds the entire list as ONE item
list_a = [1, 2, 3]
list_a.append([4, 5])
print("append:", list_a)

# extend adds each item individually
list_b = [1, 2, 3]
list_b.extend([4, 5])
print("extend:", list_b)

Removing Items from a List

remove() -- Remove by Value

The remove() method removes the first occurrence of a specified value.

fruits = ["apple", "banana", "cherry", "banana"]
fruits.remove("banana")   # Removes first "banana"
print(fruits)

If the item is not found, Python raises a ValueError.

fruits = ["apple", "banana"]
# fruits.remove("grape")  # ValueError: list.remove(x): x not in list

# Safe way: check first
if "grape" in fruits:
    fruits.remove("grape")
else:
    print("grape not found in list")

pop() -- Remove by Index

The pop() method removes an item at a given index and returns it. Without an argument, it removes the last item.

fruits = ["apple", "banana", "cherry", "date"]

# Pop the last item
last = fruits.pop()
print(f"Removed: {last}")
print(fruits)

# Pop at a specific index
second = fruits.pop(1)
print(f"Removed: {second}")
print(fruits)

clear() -- Remove All Items

The clear() method removes all items, leaving an empty list.

fruits = ["apple", "banana", "cherry"]
fruits.clear()
print(fruits)

Sorting and Reversing

sort() -- Sort In Place

The sort() method sorts the list in place (modifies the original list).

# Sort numbers in ascending order
numbers = [64, 25, 12, 22, 11]
numbers.sort()
print(numbers)

# Sort strings alphabetically
names = ["Charlie", "Alice", "Bob"]
names.sort()
print(names)

# Sort in descending order
numbers = [64, 25, 12, 22, 11]
numbers.sort(reverse=True)
print(numbers)

original = [3, 1, 4, 1, 5]
new_sorted = sorted(original)
print("Original:", original)
print("Sorted copy:", new_sorted)

reverse() -- Reverse In Place

The reverse() method reverses the order of elements in the list.

fruits = ["apple", "banana", "cherry"]
fruits.reverse()
print(fruits)

Searching Lists

count() -- Count Occurrences

The count() method returns the number of times a value appears in the list.

grades = ["A", "B", "A", "C", "A", "B"]
print(f"Number of A's: {grades.count('A')}")
print(f"Number of D's: {grades.count('D')}")

index() -- Find Position

The index() method returns the index of the first occurrence of a value.

fruits = ["apple", "banana", "cherry", "banana"]
print(fruits.index("cherry"))
print(fruits.index("banana"))   # Returns first occurrence

If the value is not found, index() raises a ValueError. Always check first with in.

fruits = ["apple", "banana", "cherry"]
search = "date"

if search in fruits:
    print(f"Found at index {fruits.index(search)}")
else:
    print(f"{search} not found")

Modifying List Elements

Since lists are mutable, you can change individual elements by assigning a new value to a specific index.

fruits = ["apple", "banana", "cherry"]
print("Before:", fruits)

# Change the second element
fruits[1] = "blueberry"
print("After:", fruits)

students = ["Alice", "Bob", "Charlie"]
grades = [85, 72, 90]

# Bob retook the exam
bob_index = students.index("Bob")
grades[bob_index] = 88

print(f"Bob's updated grade: {grades[bob_index]}")

Quick Reference: All List Methods