A Python list collects related items under one name. Put items inside square brackets and separate them with commas. A menu can use one list for drinks, another for flavors, and another for toppings. Lists can hold strings, numbers, or a mixture of both; they can also contain other lists. section 2.0 section 2.1
drinks = ["chocolate", "coffee", "decaf"] flavors = ["caramel", "vanilla", "peppermint", "raspberry", "plain"] toppings = ["chocolate", "cinnamon", "caramel"]
These three lists give a coffee shop program a small, editable menu to work with. section 2.0
A list becomes useful when the program needs to work through or choose from its items:
- Use a for loop to print each item on its own line instead of printing the whole list in Python’s bracketed display. section 2.0
- Keep a counter while looping when people need numbered menu choices. section 2.0
- Retrieve an item with its list index in square brackets, such as drinks[0]. section 2.0 section 2.1
- Remember that list indices start at 0, even when a menu shown to a customer starts numbering at 1. section 2.0 section 2.1
Turn a menu choice into a list lookup
input() returns a string, so it cannot be used directly as a list index. Convert the choice with int(), then subtract 1 when the displayed menu begins at 1. For example, drinks[int(drink) - 1] finds the first displayed drink when the customer enters 1. This links friendly menu numbering to Python’s zero-based indexing. section 2.0
Lists can also gather records. Start with an empty list using orders = [], then add order dictionaries with append(). The resulting list can be saved as structured JSON data, allowing several coffee-shop orders to travel together in one file. section 8.0
