5.6 Power Tools for Lists

Power Tools for Managing Lists

Python includes many built-in tools to make common list operations simple and fast. Today we'll look at one crucial function and a few powerful "methods" that belong to all lists.

Finding the Length with len()

The len() function is a simple but essential tool. It takes a list as an argument and returns the number of items currently in that list.

players = ["Alice", "Bob", "Charlie", "Diana"]
num_players = len(players)
print(f"There are {num_players} players on the team.") # Output: There are 4 players on the team.

Sorting a List with .sort()

The .sort() method sorts the items in a list alphabetically or numerically. Important: this method modifies the list in-place, meaning it permanently changes the original list's order.

scores = [92, 85, 100, 78]
scores.sort()
print(scores) # Output: [78, 85, 92, 100]

Removing and Getting an Item with .pop()

The .pop() method is a powerful way to remove an item. It does two things at once: it removes an item from a specific index, and it returns that item so you can use it. If you don't provide an index, it will remove and return the last item in the list.

players = ["Alice", "Bob", "Charlie"]
last_player = players.pop() # Pop the last item
print(f"We removed: {last_player}") # Output: We removed: Charlie
print(f"The list is now: {players}") # Output: The list is now: ['Alice', 'Bob']

Knowledge Check: Match the Tool to the Job

Can you remember the job of each tool? Try this quick matching game.

Live Example: Managing a Deck of Cards

This Trinket demonstrates all these tools in action. Run it, then follow the "Your Turn" instructions to experiment with the code.