Python List Methods

Overview

• Covers 11 basic list methods in Python.
• Excludes dunder methods.
• Using dot notation to access methods.

Methods

1. Append

• Usage: list.append(x)
• Adds an element to the end of the list.
• Example: people.append('Luigi') adds 'Luigi' to people.

2. Clear

• Usage: list.clear()
• Empties the list.
• Example: people.clear() results in an empty list.

3. Copy

• Usage: list.copy()
• Creates a shallow copy of the list.
• Example: copy_people = people.copy().
  • Changes to copy_people won't affect people.
  • Does not handle multi-dimensional lists correctly.

4. Count

• Usage: list.count(x)
• Counts the number of occurrences of an element in the list.
• Example: people.count('Elon') returns the count of 'Elon' in people.

5. Extend

• Usage: list.extend(iterable)
• Extends the list by appending elements from an iterable.
• Example: people.extend(['apple', 'banana']) adds 'apple' and 'banana' to people.

6. Index

• Usage: list.index(x)
• Returns the index of the first occurrence of an element.
• Example: people.index('Trump') returns the index of 'Trump'.
• Raises ValueError if the element is not found.

7. Insert

• Usage: list.insert(i, x)
• Inserts an element at a specified position.
• Example: people.insert(1, 'Luigi') inserts 'Luigi' at index 1.
• Handles boundary conditions (e.g., large positive or negative indices).

8. Pop

• Usage: list.pop([i])
• Removes and returns the element at a specified position (default is the last item).
• Example: people.pop(0) removes and returns the first element.
• The removed element can be stored for further processing.

9. Remove

• Usage: list.remove(x)
• Removes the first occurrence of an element.
• Example: people.remove('Elon') removes the first 'Elon' in people.
• Raises ValueError if the element is not found.

10. Reverse

• Usage: list.reverse()
• Reverses the order of the list in place.
• Example: people.reverse() reverses the elements in people.

11. Sort

• Usage: list.sort(key=None, reverse=False)
• Sorts the list in place.
• Example: people.sort() sorts people alphabetically.
  • Can specify a key for custom sort order.
  • reverse=True sorts in descending order.

Conclusion

• These are the 11 basic list methods in Python.
• Further customization can be done using keys and lambda functions.
• Edge cases and handling multi-dimensional lists may require special attention.
• Feedback and more tips are welcome.

End of Lecture.