Lists: creation, indexing, slicing, methods
1. 🔎 What is a List?
- A list is a collection of items stored in a single variable.
- Lists can hold numbers, strings, or even other lists.
- Lists are ordered (items have positions) and mutable (can be changed).
2. 🖥️ Creating Lists
# Empty list
my_list = []
# List of numbers
numbers = [1, 2, 3, 4, 5]
# List of strings
fruits = ["apple", "banana", "cherry"]
# Mixed data types
mixed = [10, "hello", 3.14, True]
👉 Output:
['apple', 'banana', 'cherry']
3. 📍 Indexing
- Each item in a list has a position called an index.
- Indexing starts at 0 in Python.
fruits = ["apple", "banana", "cherry"]
print(fruits[0]) # First item → apple
print(fruits[1]) # Second item → banana
print(fruits[-1]) # Last item → cherry
👉 Output:
apple
banana
cherry
4. ✂️ Slicing
- Slicing lets you get a sub-list from a list.
- Syntax:
list[start:end]start→ index where slice begins (inclusive).end→ index where slice stops (exclusive).
numbers = [10, 20, 30, 40, 50]
print(numbers[1:4]) # from index 1 to 3 → [20, 30, 40]
print(numbers[:3]) # from start to index 2 → [10, 20, 30]
print(numbers[2:]) # from index 2 to end → [30, 40, 50]
print(numbers[-3:]) # last 3 items → [30, 40, 50]
👉 Output:
[20, 30, 40]
[10, 20, 30]
[30, 40, 50]
[30, 40, 50]