Python for Engineers

Online Python Compiler 💻

pip install flask

app.py

from flask import Flask, render_template, request, jsonify

import subprocess

app = Flask(__name__)

@app.route("/")

def home():

return render_template("index.html")

@app.route("/run", methods=["POST"])

def run_code():

code = request.json.get("code", "")

try:

# Run the code in a restricted subprocess

result = subprocess.run(

["python", "-c", code],

capture_output=True,

text=True,

timeout=5

)

output = result.stdout if result.stdout else result.stderr

except Exception as e:

output = str(e)

return jsonify({"output": output})

if __name__ == "__main__":

app.run(debug=True)

templates/index.html

<!DOCTYPE html>

<head>

<title>Online Python Compiler</title>

<style>

body { font-family: Arial, sans-serif; text-align: center; }

#editor { width: 80%; height: 300px; margin: auto; border: 1px solid #ddd; }

#output { white-space: pre-wrap; background: #f4f4f4; padding: 10px; margin-top: 10px; width: 80%; }

</style>

</head>

<body>

<h1>Online Python Compiler 💻</h1>

<div id="editor">print("Hello, World!")</div>

<pre id="output">Output will appear here...</pre>

var editor = ace.edit("editor");

editor.setTheme("ace/theme/monokai");

editor.session.setMode("ace/mode/python");

function runCode() {

let code = editor.getValue();

fetch("/run", {

method: "POST",

headers: { "Content-Type": "application/json" },

body: JSON.stringify({ code: code })

})

.then(response => response.json())

.then(data => document.getElementById("output").innerText = data.output);

}

</script>

</body>

</html>

Flashcard App for Learning

import tkinter as tk

import json

import random

# File to store flashcards

FLASHCARDS_FILE = "flashcards.json"

class FlashcardApp:

def __init__(self, root):

self.root = root

self.root.title("Flashcard App")

self.root.geometry("400x300")

self.flashcards = self.load_flashcards()

self.current_flashcard = {}

# UI Elements

self.label = tk.Label(root, text="Press 'Next' to start!", font=("Arial", 14), wraplength=350)

self.label.pack(pady=20)

self.flip_button = tk.Button(root, text="Flip", command=self.flip_card)

self.flip_button.pack()

self.next_button = tk.Button(root, text="Next", command=self.next_card)

self.next_button.pack()

self.add_button = tk.Button(root, text="Add Flashcard", command=self.add_flashcard)

self.add_button.pack()

def load_flashcards(self):

try:

with open(FLASHCARDS_FILE, "r") as file:

return json.load(file)

except FileNotFoundError:

return []

def save_flashcards(self):

with open(FLASHCARDS_FILE, "w") as file:

json.dump(self.flashcards, file)

def next_card(self):

if not self.flashcards:

self.label.config(text="No flashcards available. Add some!")

else:

self.current_flashcard = random.choice(self.flashcards)

self.label.config(text=f"Q: {self.current_flashcard['question']}")

def flip_card(self):

if self.current_flashcard:

self.label.config(text=f"A: {self.current_flashcard['answer']}")

def add_flashcard(self):

add_window = tk.Toplevel(self.root)

add_window.title("Add Flashcard")

add_window.geometry("300x200")

tk.Label(add_window, text="Question:").pack()

question_entry = tk.Entry(add_window, width=40)

question_entry.pack()

tk.Label(add_window, text="Answer:").pack()

answer_entry = tk.Entry(add_window, width=40)

answer_entry.pack()

def save_new_flashcard():

question = question_entry.get()

answer = answer_entry.get()

if question and answer:

self.flashcards.append({"question": question, "answer": answer})

self.save_flashcards()

add_window.destroy()

save_button = tk.Button(add_window, text="Save", command=save_new_flashcard)

save_button.pack()

# Run the app

root = tk.Tk()

app = FlashcardApp(root)

root.mainloop()

Quiz Game with Leaderboard 🎮

import tkinter as tk

from tkinter import messagebox

import random

import json

# Load questions from a JSON file or use a dictionary

questions = [

{"question": "What keyword is used to define a function in Python?",

"options": ["func", "define", "def", "function"],

"answer": "def"},

{"question": "Which of the following is used to create a loop in Python?",

"options": ["for", "while", "do-while", "Both A and B"],

"answer": "Both A and B"},

{"question": "What is the correct way to open a file in read mode?",

"options": ["open('file.txt', 'r')", "open('file.txt', 'w')", "open('file.txt', 'rw')", "open('file.txt')"],

"answer": "open('file.txt', 'r')"},

{"question": "Which data structure follows the Last In, First Out (LIFO) principle?",

"options": ["Queue", "Stack", "List", "Dictionary"],

"answer": "Stack"},

{"question": "Which method is used to add an element to a list?",

"options": ["append()", "insert()", "extend()", "add()"],

"answer": "append()"},

{"question": "Which library is commonly used for data analysis in Python?",

"options": ["NumPy", "Pandas", "Matplotlib", "Seaborn"],

"answer": "Pandas"},

{"question": "Which symbol is used to comment a single line in Python?",

"options": ["//", "#", "/*", "--"],

"answer": "#"},

{"question": "What will be the output of `len(['Python', 'Java', 'C++'])`?",

"options": ["2", "3", "4", "Error"],

"answer": "3"},

{"question": "What does the `range(5)` function return?",

"options": ["[1,2,3,4,5]", "[0,1,2,3,4]", "(0,1,2,3,4)", "None"],

"answer": "[0,1,2,3,4]"},

{"question": "Which of the following is a mutable data type in Python?",

"options": ["Tuple", "String", "List", "Integer"],

"answer": "List"}

]

# Load leaderboard from file

def load_leaderboard():

try:

with open("leaderboard.json", "r") as f:

return json.load(f)

except FileNotFoundError:

return {}

# Save leaderboard to file

def save_leaderboard(leaderboard):

with open("leaderboard.json", "w") as f:

json.dump(leaderboard, f, indent=4)

class QuizGame:

def __init__(self, root):

self.root = root

self.root.title("Quiz Game with Leaderboard")

self.root.geometry("500x400")

self.score = 0

self.current_question = 0

self.username = ""

self.start_screen()

def start_screen(self):

"""Start screen to enter player's name."""

self.clear_window()

tk.Label(self.root, text="Enter Your Name:", font=("Arial", 14)).pack(pady=10)

self.name_entry = tk.Entry(self.root, font=("Arial", 12))

self.name_entry.pack(pady=5)

tk.Button(self.root, text="Start Quiz", command=self.start_quiz, font=("Arial", 12)).pack(pady=20)

def start_quiz(self):

"""Start the quiz after getting the user's name."""

self.username = self.name_entry.get()

if not self.username:

messagebox.showerror("Error", "Please enter your name!")

return

random.shuffle(questions)

self.score = 0

self.current_question = 0

self.show_question()

def show_question(self):

"""Display a question and answer options."""

self.clear_window()

if self.current_question < len(questions):

q_data = questions[self.current_question]

self.correct_answer = q_data["answer"]

tk.Label(self.root, text=f"Q{self.current_question + 1}: {q_data['question']}", font=("Arial", 14), wraplength=400).pack(pady=10)

self.answer_var = tk.StringVar()

for option in q_data["options"]:

tk.Radiobutton(self.root, text=option, variable=self.answer_var, value=option, font=("Arial", 12)).pack(anchor="w", padx=20)

tk.Button(self.root, text="Submit", command=self.check_answer, font=("Arial", 12)).pack(pady=10)

else:

self.show_result()

def check_answer(self):

"""Check the selected answer."""

selected_answer = self.answer_var.get()

if not selected_answer:

messagebox.showerror("Error", "Please select an answer!")

return

if selected_answer == self.correct_answer:

self.score += 1

self.current_question += 1

self.show_question()

def show_result(self):

"""Display the final score and update leaderboard."""

self.clear_window()

leaderboard = load_leaderboard()

leaderboard[self.username] = self.score

save_leaderboard(leaderboard)

tk.Label(self.root, text=f"Quiz Over! {self.username}, your score: {self.score}/{len(questions)}", font=("Arial", 14)).pack(pady=10)

tk.Button(self.root, text="View Leaderboard", command=self.show_leaderboard, font=("Arial", 12)).pack(pady=10)

tk.Button(self.root, text="Play Again", command=self.start_screen, font=("Arial", 12)).pack(pady=5)

tk.Button(self.root, text="Exit", command=self.root.quit, font=("Arial", 12)).pack(pady=5)

def show_leaderboard(self):

"""Display the leaderboard."""

self.clear_window()

leaderboard = load_leaderboard()

sorted_leaderboard = sorted(leaderboard.items(), key=lambda x: x[1], reverse=True)

tk.Label(self.root, text="🏆 Leaderboard 🏆", font=("Arial", 16, "bold")).pack(pady=10)

for rank, (player, high_score) in enumerate(sorted_leaderboard, start=1):

tk.Label(self.root, text=f"{rank}. {player} - {high_score}", font=("Arial", 12)).pack()

tk.Button(self.root, text="Back to Menu", command=self.start_screen, font=("Arial", 12)).pack(pady=10)

def clear_window(self):

"""Clear the window for new content."""

for widget in self.root.winfo_children():

widget.destroy()

# Run the application

if __name__ == "__main__":

root = tk.Tk()

app = QuizGame(root)

root.mainloop()

Habit Tracker

import sqlite3

import tkinter as tk

from tkinter import messagebox

# Database Setup

conn = sqlite3.connect("habits.db")

cursor = conn.cursor()

cursor.execute("""

CREATE TABLE IF NOT EXISTS habits (

id INTEGER PRIMARY KEY AUTOINCREMENT,

name TEXT NOT NULL,

status TEXT DEFAULT 'Pending'

)

""")

conn.commit()

# Function to add a new habit

def add_habit():

habit_name = habit_entry.get().strip()

if habit_name:

cursor.execute("INSERT INTO habits (name, status) VALUES (?, 'Pending')", (habit_name,))

conn.commit()

habit_entry.delete(0, tk.END)

load_habits()

else:

messagebox.showwarning("Warning", "Please enter a habit name!")

# Function to mark a habit as completed

def complete_habit(habit_id):

cursor.execute("UPDATE habits SET status = 'Completed' WHERE id = ?", (habit_id,))

conn.commit()

load_habits()

# Function to delete a habit

def delete_habit(habit_id):

cursor.execute("DELETE FROM habits WHERE id = ?", (habit_id,))

conn.commit()

load_habits()

# Function to load habits from the database

def load_habits():

habit_list.delete(0, tk.END)

cursor.execute("SELECT id, name, status FROM habits")

for habit in cursor.fetchall():

habit_id, name, status = habit

habit_list.insert(tk.END, f"{habit_id}. {name} - {status}")

# GUI Setup

root = tk.Tk()

root.title("Habit Tracker")

root.geometry("400x500")

tk.Label(root, text="Enter a New Habit:", font=("Arial", 12)).pack(pady=5)

habit_entry = tk.Entry(root, width=40)

habit_entry.pack(pady=5)

tk.Button(root, text="Add Habit", command=add_habit).pack(pady=5)

tk.Label(root, text="Your Habits:", font=("Arial", 12)).pack(pady=5)

habit_list = tk.Listbox(root, width=50, height=10)

habit_list.pack()

tk.Button(root, text="Mark as Completed", command=lambda: complete_habit(habit_list.get(tk.ACTIVE).split('.')[0])).pack(pady=5)

tk.Button(root, text="Delete Habit", command=lambda: delete_habit(habit_list.get(tk.ACTIVE).split('.')[0])).pack(pady=5)

load_habits()

root.mainloop()

Secure Notes App

import os

import tkinter as tk

from tkinter import messagebox, simpledialog

from cryptography.fernet import Fernet

# Generate a key file if it doesn’t exist

KEY_FILE = "secret.key"

NOTES_FILE = "secure_notes.txt"

def generate_key():

key = Fernet.generate_key()

with open(KEY_FILE, "wb") as key_file:

key_file.write(key)

def load_key():

if not os.path.exists(KEY_FILE):

generate_key()

with open(KEY_FILE, "rb") as key_file:

return key_file.read()

# Load encryption key

key = load_key()

cipher_suite = Fernet(key)

def encrypt_message(message):

return cipher_suite.encrypt(message.encode()).decode()

def decrypt_message(encrypted_message):

return cipher_suite.decrypt(encrypted_message.encode()).decode()

def save_note():

note = note_text.get("1.0", tk.END).strip()

if not note:

messagebox.showwarning("Warning", "Note cannot be empty!")

return

encrypted_note = encrypt_message(note)

with open(NOTES_FILE, "a") as file:

file.write(encrypted_note + "\n")

messagebox.showinfo("Success", "Note saved securely!")

note_text.delete("1.0", tk.END)

def load_notes():

if not os.path.exists(NOTES_FILE):

messagebox.showinfo("No Notes", "No saved notes found.")

return

with open(NOTES_FILE, "r") as file:

encrypted_notes = file.readlines()

if not encrypted_notes:

messagebox.showinfo("No Notes", "No saved notes found.")

return

password = simpledialog.askstring("Password", "Enter decryption password:", show="*")

if password: # Dummy check

try:

decrypted_notes = [decrypt_message(note.strip()) for note in encrypted_notes]

messagebox.showinfo("Your Notes", "\n\n".join(decrypted_notes))

except Exception as e:

messagebox.showerror("Error", "Failed to decrypt notes.")

else:

messagebox.showwarning("Warning", "Password cannot be empty!")

# GUI Setup

root = tk.Tk()

root.title("Secure Notes App")

root.geometry("400x400")

tk.Label(root, text="Enter your note:", font=("Arial", 12)).pack(pady=5)

note_text = tk.Text(root, height=8, width=40)

note_text.pack()

save_btn = tk.Button(root, text="Save Note", command=save_note)

save_btn.pack(pady=5)

load_btn = tk.Button(root, text="Load Notes", command=load_notes)

load_btn.pack(pady=5)

root.mainloop()

Blog Pages

Online Python Compiler 💻

Flashcard App for Learning

Quiz Game with Leaderboard 🎮

Habit Tracker

Secure Notes App