Welcome to Python Lists! A Python list is one of the most important data structures you'll use. It's an ordered, mutable collection that can store multiple items of different data types in a single variable. Lists are ordered, meaning items maintain their position. They're mutable, so you can change them after creation. They're indexed, allowing access by position starting from zero. And they allow duplicates, so the same values can appear multiple times.
Now let's learn how to create lists and access their elements. Lists are created using square brackets with items separated by commas. You can create an empty list using empty brackets or the list function. You can also create lists from ranges. To access elements, use positive indexing starting from zero, or negative indexing starting from minus one for the last element. Slicing allows you to get multiple elements using start and end positions.
Lists are mutable, meaning you can modify them after creation. You can change elements using direct assignment with square brackets. To add elements, use append to add a single item to the end, insert to add an item at a specific position, or extend to add multiple items from another iterable. To remove elements, use remove to delete the first occurrence of a value, or pop to remove and return an item at a specific index or the last item if no index is specified.
Python lists come with many useful methods and operations. The len function returns the number of items in a list. The count method counts how many times a value appears. The index method finds the position of a value. You can sort a list in place with sort, or reverse it with reverse. Lists also support operations like concatenation using the plus operator, repetition using the multiplication operator, and membership testing using the in keyword to check if an item exists in the list.
To summarize what we've learned about Python lists: Lists are ordered, mutable collections that can store multiple items of different types. You create them with square brackets and access elements using index positions. You can modify lists using direct assignment and methods like append, insert, remove, and pop. Python provides many built-in methods for common operations like getting length, sorting, and counting. Lists are fundamental data structures that you'll use frequently for storing and manipulating data in Python programs.