Lists

Syntax

[item1, item2, item3]

Examples

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

print(fruits[0])    # apple
print(fruits[-1])   # cherry (last item)
print(len(fruits))  # 3

fruits = ["apple", "banana"]

fruits.append("cherry")          # add to the end
fruits.insert(1, "blueberry")    # insert at index 1
print(fruits)  # ['apple', 'blueberry', 'banana', 'cherry']

fruits.remove("banana")          # remove by value
popped = fruits.pop()            # remove and return the last item
print(fruits, popped)

numbers = [4, 1, 3, 2]

numbers.sort()               # sorts in place, ascending
print(numbers)                # [1, 2, 3, 4]

numbers.sort(reverse=True)
print(numbers)                # [4, 3, 2, 1]

original = [3, 1, 2]
new_sorted = sorted(original)  # returns a new list, leaves original unchanged
print(original, new_sorted)

a = [1, 2, 3]
b = [4, 5]

combined = a + b          # concatenation
print(combined)            # [1, 2, 3, 4, 5]

repeated = [0] * 3
print(repeated)            # [0, 0, 0]

print(3 in a)              # True
print(10 in a)             # False

Best practices

• Use lists when the collection may grow, shrink, or be reordered; use a tuple instead for fixed, unchanging data
• Use .append() to add single items and .extend() to add all items from another iterable, not += for large loops
• Prefer sorted() when you need the original list preserved, and .sort() when modifying in place is fine
• Avoid using list as a variable name - it shadows the built-in list() type
• Use list comprehensions instead of building a list with a loop and repeated .append() calls, when the transformation is simple

At a glance

Purpose

Scripting and general-purpose applications

File extension

.py

Runs in

Python interpreter

Usually used with

Python standard library and packages

Specifications & further reading

• Python language reference

Related Python documentation