Python Programming: Examples and Tips for INFO2000 Midterm

Posted on Mar 24, 2025 in Computers

General Python Tips:

• Loops: Use for i in range(start, stop, step): for iteration.
• Lists: my_list = [1, 2, 3], access elements with my_list[index].
• Dictionaries: my_dict = {'key': 'value'}, access with my_dict['key'].
• Functions: Use def function_name(parameters): return value to define.
• Importing Libraries: Use import random, import math.
• Printing Debugging Info: Use print(variable).
• String Manipulation: .upper(), .lower(), .strip(), .split(), .join().
• File Handling: open('filename.txt', 'r') to read, open('filename.txt', 'w') to write.

1. Sum of Even Numbers (56 to 102)

print(sum(range(56, 103, 2)))

• range(56, 103, 2) generates even numbers.
• sum() computes the total.

2. List of Prime Numbers (100 to 200)

def is_prime(n):
    if n < 2:
        return False
    for i in range(2, int(n**0.5) + 1):
        if n % i == 0:
            return False
    return True

primes = [n for n in range(100, 201) if is_prime(n)]
print(primes)

• Efficiency Tip: Checking up to sqrt(n) reduces iterations.

3. Rabbit & Turtle Race Simulation

import random

def race():
    rabbit, turtle = 0, 0
    while rabbit < 50 and turtle < 50:
        rabbit += random.randint(1, 10)
        turtle += random.randint(1, 3)
        print(f"Rabbit: {rabbit}, Turtle: {turtle}")
    print("Winner:", "Rabbit" if rabbit > turtle else "Turtle")

race()

4. Number Guessing Game

import random

number = random.randint(1, 99)
low, high = 1, 99
while True:
    guess = int(input(f"Guess a number between {low} and {high}: "))
    if guess == number:
        print("Correct!")
        break
    elif guess < number:
        low = guess + 1
    else:
        high = guess - 1

5. Rock-Paper-Scissors Game

import random
choices = ["rock", "paper", "scissors"]
player = input("Choose rock, paper, or scissors: ").lower()
computer = random.choice(choices)
print(f"Computer chose {computer}")
if player == computer:
    print("It's a tie!")
elif (player == "rock" and computer == "scissors") or \
     (player == "scissors" and computer == "paper") or \
     (player == "paper" and computer == "rock"):
    print("You win!")
else:
    print("You lose!")

6. Pascal’s Triangle

def pascal(n):
    triangle = [[1]]
    for i in range(1, n):
        row = [1] + [triangle[i-1][j] + triangle[i-1][j+1] for j in range(len(triangle[i-1])-1)] + [1]
        triangle.append(row)
    for row in triangle:
        print(row)

pascal(5)

7. Magic Square (n x n)

def magic_square(n):
    magic = [[0] * n for _ in range(n)]
    i, j = 0, n // 2
    for num in range(1, n * n + 1):
        magic[i][j] = num
        i -= 1
        j += 1
        if num % n == 0:
            i += 2
            j -= 1
        elif i < 0:
            i = n - 1
        elif j == n:
            j = 0
    for row in magic:
        print(row)

magic_square(3)

8. DNA Nucleotide Frequency

def count_nucleotides(file):
    with open(file, 'r') as f:
        dna = f.read().strip()
    counts = {nucleotide: dna.count(nucleotide) for nucleotide in "ACGT"}
    print(counts)

count_nucleotides("dna.txt")

9. List of Names (First Letter & Length)

names = ["Alice", "Bob", "Charlie", "David", "Eve"]
info = [(name[0], len(name)) for name in names]
print(info)

10. Lottery Ball Selection (1-49)

import random
lottery = random.sample(range(1, 50), 6)
print(sorted(lottery))

Useful Libraries & Functions

• random.randint(a, b): Random integer between a and b.
• math.sqrt(x): Square root.
• len(list): Get list length.
• list.append(x): Add x to a list.
• string.lower(), string.upper(): Convert case.
• sorted(list): Sort elements.
• input(prompt): Get user input.
• open(file, mode): File handling ('r' for read, 'w' for write).

Extra Notes:

• try-except for Error Handling:

try:
    x = int(input("Enter a number: "))
except ValueError:
    print("Invalid input!")

• while vs. for loops:
  • while condition: runs indefinitely until condition is false.
  • for item in iterable: iterates over an object.

This should cover everything you need for the mid-term! Good luck!