Python Lists Summary

Overview of Lists in Python

  • Definition: A list is an ordered collection of items.

  • Syntax: Indicated by square brackets [], separated by commas. Example: cars = ['Suzuki', 'Toyota', 'Honda', 'Changan']

Accessing Elements

  • Indexing: Elements accessed via their index position, starting from 0.

  • Negative Indexing: -1 indicates the last item.

    • Example: bicycles[-1] returns the last bicycle.

Modifying Lists

  • Changing Elements: Modify using the index. Example: motorcycles[0] = 'ducati'.

  • Appending: Use append() to add items. Example: motorcycles.append('ducati').

  • Inserting: Use insert(index, item) to add at a specific index. Example: motorcycles.insert(0, 'ducati').

  • Removing: Use del, pop(), or remove() to delete items from a list.

    • del motorcycles[0] removes by index.

    • popped_motorcycle = motorcycles.pop() removes and stores the last item.

    • motorcycles.remove('ducati') removes by value.

Organizing a List

  • Sorting: Use sort() for permanent sorting, sorted() for temporary sorting.

  • Reversing: Use reverse() to reverse the order of the list.

List Length and Errors

  • Length: Use len(list). Example: len(cars) returns the number of items.

  • Index Errors: Occur when accessing an index out of range. Use negative indexing to access from the end, but remember it can also produce errors with empty lists.