Derive and Display Categories

Build the category list from your data using set, sorted, and join

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Before asking the player to choose a category, the quiz needs to show which categories exist. You could write a string by hand, but that string would go stale the moment you add a question in a new category. The categories are already in your data — read them from there.

set()

A set is a collection that holds each value only once — duplicates are removed automatically:

words = ["apple", "banana", "apple", "cherry", "banana"]
unique = set(words)
# {"apple", "banana", "cherry"}

Ten questions share six categories, so iterating over QUESTIONS produces duplicates. Wrapping that in set() gives you each category exactly once.

sorted()

sorted() takes any collection and returns a new list in alphabetical order:

sorted({"banana", "apple", "cherry"})
# ["apple", "banana", "cherry"]

Sets have no guaranteed order, so sorted() ensures the output is consistent every time.

", ".join()

join() turns a list of strings into a single string, placing the separator between each item:

items = ["apple", "banana", "cherry"]
print(", ".join(items))
# apple, banana, cherry

The string before .join() is the separator — ", " puts a comma and a space between each item.

Putting it together

categories = sorted(set(q["category"] for q in QUESTIONS))
print("Categories: " + ", ".join(categories))

q["category"] for q in QUESTIONS reads every category value from QUESTIONS — ten values, with duplicates. set(...) removes the duplicates. sorted(...) alphabetizes them. ", ".join(categories) formats them as a comma-separated string for the player to read.

Instructions

Print the available categories before each round.

At the top of the while True: loop, before the try/except, add categories = sorted(set(q["category"] for q in QUESTIONS)) — the inner part reads every category from QUESTIONS (with duplicates), set(...) removes duplicates, and sorted(...) alphabetizes them.
On the next line, add print("Categories: " + ", ".join(categories)) — ", ".join(categories) turns the sorted list into a single comma-separated string.

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QUESTIONS = [
    {"text": "What is the type of the value 3.14?", "options": ["int", "str", "float", "bool"], "correct": 3, "category": "types"},
    {"text": "What keyword defines a function in Python?", "options": ["for", "def", "if", "class"], "correct": 2, "category": "functions"},
    {"text": "What does print() do?", "options": ["Stores a value", "Returns a number", "Displays output", "Reads input"], "correct": 3, "category": "output"},
    {"text": "What type does input() always return?", "options": ["int", "float", "str", "bool"], "correct": 3, "category": "output"},
    {"text": "Which keyword starts a for loop?", "options": ["loop", "repeat", "for", "each"], "correct": 3, "category": "loops"},
    {"text": "What does len() return?", "options": ["The first item", "The last item", "The number of items", "The sum"], "correct": 3, "category": "basics"},
    {"text": "What is the result of 10 // 3?", "options": ["3.33", "3", "1", "0"], "correct": 2, "category": "basics"},
    {"text": "Which keyword exits a loop early?", "options": ["exit", "return", "stop", "break"], "correct": 4, "category": "loops"},
    {"text": "What does elif stand for?", "options": ["else if", "elif loop", "end loop if", "extra loop"], "correct": 1, "category": "conditionals"},
    {"text": "What does a function return with no return statement?", "options": ["0", "False", "None", "Error"], "correct": 3, "category": "functions"},
]

def ask_question(q):
    print(q["text"])
    print()
    print(f"  1) {q['options'][0]}")
    print(f"  2) {q['options'][1]}")
    print(f"  3) {q['options'][2]}")
    print(f"  4) {q['options'][3]}")
    print()
    while True:
        answer_text = input("Your answer (1-4): ")
        try:
            answer = int(answer_text)
        except ValueError:
            print("Please enter 1, 2, 3, or 4.")
            continue
        if answer < 1 or answer > 4:
            print("Please enter 1, 2, 3, or 4.")
            continue
        break
    is_correct = answer == q["correct"]
    print()
    print(f"You answered: {answer}")
    if is_correct:
        print("Correct!")
    else:
        print(f"Wrong! The correct answer was option {q['correct']}.")
    return is_correct

def show_results(score, total):
    print(f"Score: {score}/{total}")
    if score == total:
        print("Perfect score!")
    elif score >= 2:
        print("Great job!")
    elif score >= 1:
        print("Not bad!")
    else:
        print("Keep practicing!")

def run_quiz(questions=QUESTIONS, num=None):
    if num is None:
        num = len(questions)
    score = 0
    streak = 0
    questions_for_round = questions[:num]
    total = len(questions_for_round)
    print(f"=== Python Quiz ({total} questions) ===")
    print()
    for q in questions_for_round:
        result = ask_question(q)
        if result:
            score = score + 1
            streak = streak + 1
            if streak >= 3:
                print(f"  Hot streak! ({streak} in a row)")
        else:
            streak = 0
    show_results(score, total)

while True:
    # Step 1: categories = sorted(set(q["category"] for q in QUESTIONS))
    # Step 2: print("Categories: " + ", ".join(categories))
    try:
        num_input = input(f"How many questions? (1-{len(QUESTIONS)}, enter for all): ").strip()
        if num_input:
            num = int(num_input)
        else:
            num = len(QUESTIONS)
    except ValueError:
        num = len(QUESTIONS)
    print()
    run_quiz(num=num)
    print()
    again = input("Play again? (y/n): ")
    if again != "y":
        break

print("Thanks for playing!")