Important Python Collection Data Types
Python provides several built-in collection data types. The most commonly used are list, tuple, set, and dictionary.
1. List
Description: Ordered and mutable collection
- Allows duplicate values
- Mutable (can be changed)
- Uses square brackets
[]
lst = [1, 2, 3, 3]
lst[0] = 10
When to use: When data needs to be ordered and modified frequently.
2. Tuple
Description: Ordered and immutable collection
- Allows duplicate values
- Cannot be changed after creation
- Uses parentheses
()
t = (1, 2, 3)
# t[0] = 10 ❌ Not allowed
When to use: For fixed data such as coordinates or records.
3. Set
Description: Unordered collection of unique elements
- Does not allow duplicates
- Mutable
- No indexing
- Uses curly braces
{}
s = {1, 2, 3, 3}
print(s) # {1, 2, 3}
When to use: To remove duplicates or perform set operations.
4. Dictionary
Description: Collection of key-value pairs
- Keys must be unique
- Values can be duplicated
- Mutable
- Uses
{key: value}format
d = {"name": "Alice", "age": 25}
d["age"] = 26
When to use: When data is best represented as key-value pairs.
Quick Comparison Table
| Type | Ordered | Mutable | Duplicates | Main Use |
|---|---|---|---|---|
| List | Yes | Yes | Yes | Changeable data |
| Tuple | Yes | No | Yes | Fixed data |
| Set | No | Yes | No | Unique items |
| Dictionary | Yes* | Yes | No (keys) | Key-value data |