Functions and collections

Reuse logic with functions and model data with lists and dictionaries.

Beginner 15 min read Lesson 7 of 480 Challenge included

What you will be able to do

Define functions with defaults
Iterate over dictionaries
Use list comprehensions

Functions name a piece of logic. Lists keep order, dictionaries map keys to values. Together they cover most everyday programming.

collections.pyPython

def average(values):
    if not values:
        return 0
    return sum(values) / len(values)

scores = {"html": 88, "css": 92, "js": 79}

for skill, score in scores.items():
    print(f"{skill.upper()}: {score}")

passed = [skill for skill, score in scores.items() if score >= 80]
print(f"Passed: {passed}")
print(f"Average: {average(list(scores.values())):.1f}")

Argument: A value passed into a function.
Default: A parameter value used when the argument is omitted.
Mutable: A value that can be changed in place, like a list.
Comprehension: A concise expression that builds a collection.

Your turn

Filter the passing scores

Medium

Build a list of skill names with a score of 80 or more using a comprehension.

PYTHON · starter

scores = {"html": 88, "css": 72, "js": 91}
# your code here

Check your understanding before moving on.

Knowledge checkQuestion 1

Which method returns key-value pairs from a dictionary?

Select an answer to continue

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