Coding – Step 10.4 – Edit & Remove Tasks (with closing: Python vs PHP and Large Data)

In Step 10.3 we built a menu-driven To-Do list with options to add, view, and exit.
But a real list isn’t useful unless you can manage it: some tasks must be marked done ✅, others should be removed 🗑️.

In this lesson we extend the program with functions to:

• mark a task as completed,
• delete a task from the list.

You’ll learn how to:

• work with indexes (numeric positions) in a list,
• update values inside a list (modify a field),
• remove elements using del or pop().

🎯 Goal

Extend the menu with:

• [A] Add task
• [V] View tasks
• [M] Mark task as completed
• [D] Delete task
• [X] Exit

📝 Updated code

# todo_edit_remove.py

tasks = []  # Each task is a dict: {"text": "...", "done": False}

def show_menu():
    print("\n=== TO-DO MENU ===")
    print("[A] Add task")
    print("[V] View tasks")
    print("[M] Mark task as complete")
    print("[D] Delete task")
    print("[X] Exit")

def add_task():
    text = input("Write the new task: ").strip()
    if text:
        tasks.append({"text": text, "done": False})
        print(f"✅ '{text}' added to the list!")
    else:
        print("⚠️ You didn't write anything, task not added.")

def view_tasks():
    if not tasks:
        print("📭 No tasks available.")
        return
    print("\n📋 Your tasks:")
    for i, t in enumerate(tasks, start=1):
        status = "✅" if t["done"] else "⭕"
        print(f"{i}. {status} {t['text']}")

def mark_task():
    view_tasks()
    if not tasks:
        return
    try:
        num = int(input("Which number do you want to mark as complete? "))
        if 1 <= num <= len(tasks):
            tasks[num-1]["done"] = True
            print(f"🎉 '{tasks[num-1]['text']}' marked as complete!")
        else:
            print("❌ Invalid number.")
    except ValueError:
        print("⚠️ You must enter a number.")

def delete_task():
    view_tasks()
    if not tasks:
        return
    try:
        num = int(input("Which number do you want to delete? "))
        if 1 <= num <= len(tasks):
            removed = tasks.pop(num-1)
            print(f"🗑️ '{removed['text']}' removed from the list.")
        else:
            print("❌ Invalid number.")
    except ValueError:
        print("⚠️ You must enter a number.")

def main():
    print("Welcome to your To-Do List!")
    while True:
        show_menu()
        choice = input("Choose an option: ").strip().lower()

        if choice == "a":
            add_task()
        elif choice == "v":
            view_tasks()
        elif choice == "m":
            mark_task()
        elif choice == "d":
            delete_task()
        elif choice == "x":
            print("Goodbye! 👋")
            break
        else:
            print("❌ Invalid command, try again.")

if __name__ == "__main__":
    main()

🔍 How it works

• tasks = [] → the list now stores dictionaries, each with text and done.
• mark_task() → shows tasks, asks for a number, sets done = True.
• delete_task() → shows tasks, asks for a number, removes with pop().
• enumerate(..., start=1) numbers tasks for humans (1-based).
• Invalid input is handled with try/except.

💡 Possible improvements

• Add an option to unmark a task (undo “completed”).
• Save tasks to a file (next step).
• Add colors (e.g., with colorama).

🧪 Exercises

1. Add an option to mark all tasks as completed.
2. Change mark_task() to toggle state (completed ↔ not completed).
3. Add a [C] Clear all command that empties the list after confirmation.

🚫 Common mistakes

• Forgetting to check if the list is empty before asking for a number.
• Not converting input to int, causing type errors.
• Using wrong indexes (remember Python is 0-based, while we display from 1).

📌 Key takeaways

• With indexes you can target and manage individual list items.
• Dictionaries make each task’s state clear (text + completed).
• We added essential features: mark as done and delete.

Closing – Python vs PHP and a first look at large data

After building a To-Do list in Python and a similar app in PHP, you might think they’re the same. Both handle lists, input/output, saving, and logic.
In reality, Python and PHP have different histories, goals, and usage contexts.

✅ Similarities

• Both are interpreted languages.
• Both can build interactive applications and manipulate data.
• Both can be used for web and local scripts.

🚦 Key differences

🤔 When to use Python vs PHP?

Choose Python if…

• You need to analyze or process large amounts of data.
• You’re into AI, machine learning, or automation.
• You want a multi-purpose language beyond the web.

Choose PHP if…

• You want to create/manage a dynamic website quickly.
• You use CMSs like WordPress or Drupal.
• You need to connect web interfaces to SQL databases for real users.

📦 First look at large-data work

Scenario: a CSV with 1 million sales rows.

Python → direct analysis with Pandas

import pandas as pd

df = pd.read_csv("vendite.csv")

print("Row count:", len(df))
print("Total sales:", df["totale"].sum())

df2025 = df[df["anno"] == 2025]
print("Rows for 2025:", len(df2025))

👉 In a few lines, Python loads and analyzes millions of records.

PHP → presentation via SQL database

<?php
$conn = new mysqli("localhost", "user", "password", "database");

$sql = "SELECT COUNT(*) as rows FROM vendite";
$res = $conn->query($sql)->fetch_assoc();
echo "Total rows: " . $res["rows"];

$sql = "SELECT SUM(totale) as total FROM vendite WHERE anno = 2025";
$res = $conn->query($sql)->fetch_assoc();
echo "Total sales 2025: " . $res["total"];
?>

👉 PHP doesn’t analyze in memory; it queries the database and presents results.

🔍 Two useful metaphors

• Python is a scientific lab: it ingests data, transforms it, computes statistics, finds patterns.
• PHP is a web storefront: it takes prepared data and shows it to users dynamically.

🧪 Reflection exercises

1. Write a Python script to compute the average of a numeric field in a large CSV.
2. Write a PHP script that shows the same aggregates, but from a MySQL database.
3. Compare the experience: where do you need analysis, and where presentation?

📌 Final takeaways

• Python and PHP aren’t competitors; they serve different purposes.
• Python → analysis, automation, large data, AI.
• PHP → dynamic web, user interfaces, CMS, databases.
• Together they shine: Python processes data, PHP exposes it to users.