Sidney Shapiro, PhD
Assistant Professor of Business Analytics
Applied AI Researcher
Google Developer Group Organizer

Python code examples

Variables and printing variables_and_print.py

# Strings hold text — use quotes around wizard names and spells
wizard_name = "Hermione"
spell = "Lumos"

# print() sends output to the screen (your "incantation" to the computer)
print("Welcome,", wizard_name)
print(spell, "— the tip of your wand glows!")

# You can combine text with + (concatenation)
greeting = "Hello, " + wizard_name + "!"
print(greeting)

Numbers and type conversion type_conversion.py

# Integers are whole numbers (house points, year level)
house_points = 50
year = 3

# Floats can have decimals (potion strength, quiz scores)
potion_strength = 7.5

# input() always returns a string — convert before doing math
points_text = "25"          # imagine this came from input()
points = int(points_text)   # turn "25" into the number 25
total = house_points + points
print("Total house points:", total)

# str() turns a number into text for friendly messages
print("You are in year " + str(year))

f-strings (modern way to mix text and variables) f_strings_modern_way_to_mix_text_and_variables.py

spell = "Wingardium Leviosa"
caster = "Hermione"
attempts = 3

# f"..." lets you embed variables inside { }
print(f"{caster} cast {spell} ({attempts} tries)")

# You can put expressions inside the braces too
points = 15
print(f"House earns {points * 2} bonus points!")

Booleans and simple math booleans_and_simple_math.py

# True and False are special values used in conditions later
has_wand = True
is_petrified = False

dark_points = 12
good_deed_points = 20
net_points = good_deed_points - dark_points

print("Has wand:", has_wand)
print("Net house points:", net_points)

Python code examples

Creating and using lists inventory.py

# A list stores multiple items in order — like items in your trunk
inventory = ["wand", "cloak", "map"]
print(inventory[0])   # first item: wand (indexes start at 0)
print(len(inventory)) # how many items you are carrying

# append() adds to the end; pop() removes the last item (or one you choose)
inventory.append("time-turner")
found = inventory.pop()   # pick up the last item you added
print("You found:", found)
print("Still carrying:", inventory)

Assignment vs. equality list_basics.py

# = assigns a value; == checks whether two values match
favorite_spell = "Expelliarmus"   # assignment

if favorite_spell == "Expelliarmus":   # equality check
    print("Disarming charm ready!")
else:
    print("Different spell selected.")

# in checks whether something is inside a list
spells_known = ["Lumos", "Nox", "Accio"]
if "Accio" in spells_known:
    print("You know how to summon objects!")

List slicing (grab part of a list) list_slicing_grab_part_of_a_list.py

owls_subjects = ["Charms", "Potions", "Herbology", "Defense", "Astronomy"]

# [start:end] — end is not included; negative index counts from the end
first_two = owls_subjects[0:2]      # ["Charms", "Potions"]
last_one = owls_subjects[-1]        # "Astronomy"
middle = owls_subjects[1:4]         # three subjects in the middle

print("First exams:", first_two)
print("Final exam:", last_one)

insert, remove, and sort insert_remove_and_sort.py

team = ["Harry", "Ron", "Hermione"]

team.insert(1, "Neville")   # add at index 1 (second position)
team.remove("Ron")          # remove by value (must exist exactly once)
team.sort()                 # alphabetize the list in place

print("Quidditch squad:", team)
print("How many players:", len(team))

Python code examples

For loops over a list for_loops.py

# Loop through each house and print a cheer
houses = ["Gryffindor", "Hufflepuff", "Ravenclaw", "Slytherin"]

for house in houses:
    print("Points for", house, "— ten points!")

# range() gives a sequence of numbers — useful for counting spells
for i in range(3):
    print("Practice swing", i + 1)

Summing and averaging (stats with loops) scores_stats.py

# Track quiz scores and find the total and average
scores = [88, 92, 75, 95, 81]
total = 0

for score in scores:
    total = total + score   # add each score to the running total

average = total / len(scores)
print("Total points:", total)
print("Average score:", round(average, 1))

enumerate() — loop with an index counter enumerate_loop_with_an_index_counter.py

# Useful when you need "spell 1, spell 2..." while looping
spells = ["Lumos", "Nox", "Accio"]

for number, spell in enumerate(spells, start=1):
    print(f"Lesson {number}: learn {spell}")

Finding min, max, and building a new list finding_min_max_and_building_a_new_list.py

quiz_scores = [72, 95, 88, 61, 90]
print("Highest:", max(quiz_scores))
print("Lowest:", min(quiz_scores))

# Build a list of passing grades only
passing = []
for score in quiz_scores:
    if score >= 70:
        passing.append(score)

print("Passed:", passing)

Python code examples

if / elif / else (Sorting Hat style) sorting_hat_simple.py

# Simple branching — like the hat choosing a house
trait = "brave"

if trait == "brave":
    house = "Gryffindor"
elif trait == "loyal":
    house = "Hufflepuff"
elif trait == "clever":
    house = "Ravenclaw"
else:
    house = "Slytherin"

print("The hat cries:", house + "!")

Nested conditions and membership spell_permissions.py

# Check multiple conditions before allowing a spell
spell = "Patronus"
level = 5
advanced_spells = ["Patronus", "Expecto Patronum"]

if spell in advanced_spells and level >= 5:
    print("You may attempt the charm.")
elif spell in advanced_spells:
    print("Come back when you are year 5 or higher.")
else:
    print("That spell is not on the restricted list.")

Comparison operators comparison_operators.py

galleons = 8

if galleons < 5:
    print("You cannot afford a new quill.")
elif galleons == 5:
    print("Exact change for one quill!")
elif galleons > 20:
    print("Splurge at Flourish and Blotts!")
else:
    print("Save up a little more.")

# != means "not equal"
house = "Slytherin"
if house != "Gryffindor":
    print("Different common room rules apply.")

Sorting Hat with random choice sorting_hat.py

import random

traits = ["brave", "loyal", "clever", "ambitious"]
picked = random.choice(traits)   # pick one trait at random

if picked == "brave":
    print("Gryffindor!")
elif picked == "loyal":
    print("Hufflepuff!")
elif picked == "clever":
    print("Ravenclaw!")
else:
    print("Slytherin!")
print("(The hat sensed:", picked + ")")

Python code examples

Dictionary basics student_record.py

# Keys label values — like a student record or spell book entry
student = {
    "name": "Harry",
    "house": "Gryffindor",
    "points": 120
}

# Access by key; update with assignment
print(student["name"], "has", student["points"], "points")
student["points"] = student["points"] + 10
print("After winning the match:", student["points"])

Looping through keys and values house_points.py

# House point totals — keys are houses, values are scores
house_points = {
    "Gryffindor": 350,
    "Ravenclaw": 310,
    "Hufflepuff": 290,
    "Slytherin": 275
}

for house, points in house_points.items():
    print(house + ":", points, "points")

# get() returns a default if the key is missing (safer than [])
owl_grade = student.get("owls", "not yet taken")
print("OWLs:", owl_grade)

Nested dictionaries (dict inside a dict) nested_roster.py

# Store several students — each value is another dictionary
roster = {
    "harry": {"house": "Gryffindor", "year": 5},
    "luna": {"house": "Ravenclaw", "year": 4}
}

print(roster["luna"]["house"])   # two keys in a row

roster["harry"]["points"] = 50
print("Harry now has", roster["harry"]["points"], "points")

Spell book — keys as spell names spell_book.py

spell_book = {
    "Lumos": "Creates light at wand tip",
    "Nox": "Extinguishes light",
    "Accio": "Summons an object"
}

# Loop through spell names only
for spell_name in spell_book.keys():
    print(spell_name, "—", spell_book[spell_name])

Python code examples

Reading and converting user input user_input.py

# input() pauses the program and waits for the player to type
name = input("What is your wizard name? ")
print("Nice to meet you,", name)

# Always convert before comparing numbers or doing math
age_text = input("How old are you? ")
age = int(age_text)
if age >= 11:
    print("You may receive your Hogwarts letter!")
else:
    print("A few more years of Muggle school...")

While loop — number guessing game guessing_game.py

# The loop keeps running until the player guesses the secret number
secret = 7
guessed = False

while not guessed:
    guess_text = input("Guess the number of galleons (1-10): ")
    guess = int(guess_text)

    if guess == secret:
        print("Correct! The vault opens.")
        guessed = True
    elif guess < secret:
        print("Too low — try again.")
    else:
        print("Too high — try again.")

Cleaning input with .strip() and .lower() cleaning_input_with_strip_and_lower.py

# Players type extra spaces or CAPS — normalize before you compare
answer = input("Cast Lumos or Nox? ")
answer = answer.strip().lower()   # "  LUMOS  " becomes "lumos"

if answer == "lumos":
    print("Light!")
elif answer == "nox":
    print("Darkness.")
else:
    print("The wand sputters — unknown spell.")

Menu loop with break to quit menu_loop.py

# while True runs forever until break stops the loop
while True:
    print("\n--- Common room ---")
    choice = input("(t)udy, (s)leep, (q)uit: ").strip().lower()

    if choice == "q":
        print("Goodnight!")
        break          # jump out of the loop
    elif choice == "t":
        print("You open your textbook...")
    elif choice == "s":
        print("You rest by the fire.")
    else:
        print("Pick t, s, or q.")

Python code examples

Defining and calling functions spell_functions.py

# def creates a reusable block — name it like a spell
def cast_lumos():
    print("* Your wand tip glows with a soft light *")

def award_points(house, amount):
    # Parameters let you pass in different values each time
    print(house, "earns", amount, "points!")

cast_lumos()
award_points("Gryffindor", 10)
award_points("Ravenclaw", 5)

Return values return_values.py

# return sends a result back to whoever called the function
def spell_power(level, practice_hours):
    power = level * 10 + practice_hours
    return power

my_power = spell_power(3, 12)
print("Spell strength:", my_power)

def is_passing(score):
    return score >= 70

if is_passing(85):
    print("Outstanding — you passed your OWL!")

Default parameter values default_parameter_values.py

def greet(name, greeting="Hello"):
    # If the caller skips greeting, "Hello" is used automatically
    print(f"{greeting}, {name}!")

greet("Neville")
greet("Draco", greeting="Well, well")

Function that uses a list function_that_uses_a_list.py

import random

def pick_opponent(players):
    # random.choice needs a list (or tuple) to pick from
    return random.choice(players)

duelists = ["Harry", "Draco", "Cedric"]
print("Today's opponent:", pick_opponent(duelists))

Python code examples

Game loop with rooms as functions adventure_game.py

# playing controls whether the adventure continues
playing = True

def great_hall():
    print("You stand in the Great Hall. Candles float overhead.")
    choice = input("Go to (c)ourtyard or (l)ibrary? ")
    if choice == "c":
        courtyard()
    elif choice == "l":
        library()
    else:
        print("You hesitate and stay put.")

def courtyard():
    print("Cold air. The fountain is frozen.")
    if input("Return to hall? (y/n) ") == "y":
        great_hall()
    else:
        print("You explore the grounds...")

def library():
    print("Thousands of books whisper on the shelves.")
    playing = False   # local variable — see Module 9 for global
    print("You found a secret passage. Game over!")

while playing:
    great_hall()
    # In a full game, set playing = False when the player wins or quits

Player inventory as a dictionary player_inventory_as_a_dictionary.py

# Track items and whether the player has them (True/False)
inventory = {"wand": True, "cloak": False, "map": True}

def show_inventory(bag):
    print("--- Your bag ---")
    for item, has_it in bag.items():
        status = "yes" if has_it else "no"
        print(f"  {item}: {status}")

def pick_up(bag, item_name):
    bag[item_name] = True
    print(f"You picked up the {item_name}.")

pick_up(inventory, "cloak")
show_inventory(inventory)

Room lookup table (data + functions) rooms_lookup.py

rooms = {
    "hall": "Candles float. Long tables groan with food.",
    "yard": "Cold grass. The Whomping Willow creaks.",
    "tower": "Spiral stairs. Owls hoot above."
}

def enter(room_key):
    description = rooms.get(room_key, "You are lost in mist.")
    print(description)

enter("hall")
enter("dungeon")   # not in dict — uses default message

Python code examples

global flag and a simple menu menu_duel.py

# Use global when a function must change a variable defined outside it
game_over = False

def duel():
    global game_over
    print("You raise your wand...")
    move = input("Cast (s)tun or (r)un? ")
    if move == "r":
        print("You escape!")
        game_over = True
    else:
        print("Stupefy! The duel continues.")

while not game_over:
    print("\n--- Hogwarts adventure ---")
    action = input("(d)uel, (i)nventory, (q)uit: ")
    if action == "d":
        duel()
    elif action == "q":
        game_over = True
    else:
        print("Your bag: wand, chocolate frogs")

Simple “animation” with print simple_animation_with_print.py

# Repeat prints to suggest movement (clear screen in full projects)
import time

for step in range(3):
    print("The owl flies" + "." * (step + 1))
    time.sleep(0.5)   # pause half a second between frames

Clear the screen between scenes (terminal games) clear_the_screen_between_scenes_terminal_games.py

import os
import time

def clear():
    # "cls" on Windows, "clear" on Mac/Linux
    os.system("cls" if os.name == "nt" else "clear")

for scene in ["Owl arrives...", "Letter opens...", "Train departs..."]:
    clear()
    print(scene)
    time.sleep(1)

Random encounter mini-game random_encounter.py

import random

encounters = ["troll in the corridor", "friendly ghost", "lost first-year"]
event = random.choice(encounters)
print("You round the corner and see a", event + "!")

roll = random.randint(1, 6)   # random whole number from 1 to 6
if roll >= 4:
    print(f"You rolled {roll} — success!")
else:
    print(f"You rolled {roll} — hide behind a statue.")

Python code examples

Fetching JSON from an API (install requests first: pip install requests) advice_api.py

import requests

# APIs return live data — here we ask a free “advice” service for a quote
url = "https://api.adviceslip.com/advice"
response = requests.get(url)

# Check status — 200 means OK
if response.status_code == 200:
    data = response.json()          # parse JSON into a Python dict
    print("Hermione says:", data["slip"]["advice"])
else:
    print("Could not reach the owl post:", response.status_code)

Working with nested JSON working_with_nested_json.py

# Many APIs nest data — use keys step by step
# Example structure (your real API may look different):
iss_position = {
    "iss_position": {"latitude": "45.1234", "longitude": "-75.5678"},
    "timestamp": 1710000000
}

lat = iss_position["iss_position"]["latitude"]
lon = iss_position["iss_position"]["longitude"]
print("International Space Station near:", lat, lon)

Loop through a list inside JSON loop_through_a_list_inside_json.py

# Many APIs return a list of objects — loop and print each one
# (sample data — real API responses look similar)
trivia = {
    "results": [
        {"question": "What is the counter-spell to Lumos?", "answer": "Nox"},
        {"question": "Who teaches Transfiguration?", "answer": "McGonagall"}
    ]
}

for item in trivia["results"]:
    print("Q:", item["question"])
    print("A:", item["answer"])
    print("---")

Cat facts API (no API key required) cat_fact.py

import requests

url = "https://catfact.ninja/fact"
response = requests.get(url, timeout=10)

if response.status_code == 200:
    fact = response.json()
    print("Did you know?")
    print(fact["fact"])
else:
    print("Could not fetch fact:", response.status_code)

Python code examples

Query parameters and building a URL datamuse_rhymes.py

import requests

# Many APIs use ?key=value to filter results
base = "https://api.datamuse.com/words"
params = {"rel_rhy": "wand", "max": 3}   # words that rhyme with “wand”
response = requests.get(base, params=params)

if response.status_code == 200:
    words = response.json()   # list of dicts
    for entry in words:
        print(entry["word"])

Error handling for network code error_handling_for_network_code.py

import requests

try:
    r = requests.get("https://httpbin.org/status/404", timeout=5)
    r.raise_for_status()   # raises an error for 4xx/5xx responses
except requests.exceptions.HTTPError:
    print("The spell fizzled — page not found.")
except requests.exceptions.RequestException:
    print("No connection. Check Wi-Fi and try again.")

Search-style API (movie title lookup pattern) search_style_api_movie_title_lookup_pattern.py

import requests

# OMDB and similar services use &t= for title and often need an API key
# Sign up at omdbapi.com for a free key, then paste it below
API_KEY = "your_key_here"
title = "Harry Potter"

params = {"t": title, "apikey": API_KEY}
response = requests.get("http://www.omdbapi.com/", params=params, timeout=10)

if response.status_code == 200:
    movie = response.json()
    if movie.get("Response") == "True":
        print(movie["Title"], "(", movie["Year"], ")")
        print("Plot:", movie["Plot"][:80], "...")
    else:
        print("Movie not found:", movie.get("Error"))

Save API text to a file save_fact_to_file.py

import requests

response = requests.get("https://catfact.ninja/fact", timeout=10)
if response.status_code == 200:
    text = response.json()["fact"]
    # "w" creates/overwrites a file; always close files or use "with"
    with open("daily_fact.txt", "w", encoding="utf-8") as f:
        f.write(text)
    print("Saved to daily_fact.txt")

Python code examples

Turtle graphics — draw a simple shape

import turtle

# Create a window and a “turtle” pen
screen = turtle.Screen()
screen.title("Hogwarts badge sketch")
pen = turtle.Turtle()
pen.speed(3)

# Draw a triangle (one side of a house crest)
for side in range(3):
    pen.forward(100)
    pen.left(120)

pen.hideturtle()
screen.mainloop()   # keeps the window open until you close it

Lists + loops + functions — a mini recap

# Combine ideas from the whole course
houses = ["Gryffindor", "Hufflepuff", "Ravenclaw", "Slytherin"]

def cheer(house_name):
    return "Ten points to " + house_name + "!"

for h in houses:
    print(cheer(h))

# You are ready for files, classes, web apps, data science, and more!

Colors and a square (house colors) turtle_colors_square.py

import turtle

pen = turtle.Turtle()
pen.speed(5)
pen.color("darkred")   # Gryffindor-ish

for _ in range(4):
    pen.forward(80)
    pen.left(90)

pen.color("gold")
pen.penup()
pen.goto(10, 10)
pen.pendown()
pen.dot(15)   # small circle dot

turtle.done()

Simple star with a loop turtle_star.py

import turtle

star = turtle.Turtle()
star.color("navy")
star.begin_fill()

for point in range(5):
    star.forward(120)
    star.right(144)   # 144 degrees makes a five-point star

star.end_fill()
turtle.done()