Python - Lists
Lists in Python are used to store multiple items in a single variable. They are one of Python's most flexible data structures.
Creating a List
You can create a list by placing elements inside square brackets [].
python
my_list = [1, 2, 3, 4, 5] print(my_list)
List Indexing and Slicing
Lists are ordered and indexable. Index starts from 0.
python
print(my_list[0]) # First element print(my_list[-1]) # Last element print(my_list[1:4]) # Slice from index 1 to 3
List Methods
Python provides several built-in methods to manipulate lists.
python
my_list.append(6) my_list.insert(0, 0) my_list.remove(3) my_list.pop() my_list.sort() my_list.reverse() print(my_list)
Looping Through Lists
You can use loops to iterate through list elements.
python
for item in my_list: print(item)
List Comprehension
A concise way to create lists in Python.
python
squares = [x**2 for x in range(10)] print(squares)
Nested Lists
Lists can contain other lists as elements.
python
nested = [[1, 2], [3, 4], [5, 6]] print(nested[0][1]) # Output: 2
Pros and Cons of Python Lists
Pros:
- Dynamic sizing
- Heterogeneous data types allowed
- Powerful built-in methods
Cons:
- Slower than arrays for large data (use NumPy)
- Memory overhead