Friday, 07 February 2025

A complete example using Python lists to solve practical problems

Here is a complete example using Python lists, demonstrating how to create, manipulate, and utilize lists to solve practical problems.

Example: Student Grade Management System

Problem Description

We need to create a simple student grade management system with the following features:

1. Add student grades.
2. Calculate the class average grade.
3. Find the highest and lowest grades.
4. List all passing grades (≥60).

Code Implementation

# Create an empty list to store student grades
student_grades = []

# Add a student grade
def add_grade(grade):
    student_grades.append(grade)
    print(f"Added grade: {grade}")

# Calculate the class average grade
def calculate_average():
    if not student_grades:
        return 0
    return sum(student_grades) / len(student_grades)

# Find the highest and lowest grades
def find_max_min():
    if not student_grades:
        return None, None
    return max(student_grades), min(student_grades)

# List all passing grades (≥60)
def list_passing_grades():
    passing_grades = [grade for grade in student_grades if grade >= 60]
    return passing_grades

# Main program
def main():
    # Add some student grades
    add_grade(85)
    add_grade(92)
    add_grade(58)
    add_grade(73)
    add_grade(45)

    # Calculate and print the average grade
    average_grade = calculate_average()
    print(f"Average grade: {average_grade:.2f}")

    # Find and print the highest and lowest grades
    max_grade, min_grade = find_max_min()
    print(f"Highest grade: {max_grade}")
    print(f"Lowest grade: {min_grade}")

    # List all passing grades
    passing_grades = list_passing_grades()
    print(f"Passing grades: {passing_grades}")

# Run the main program
if __name__ == "__main__":
    main()

Output

Added grade: 85
Added grade: 92
Added grade: 58
Added grade: 73
Added grade: 45
Average grade: 70.60
Highest grade: 92
Lowest grade: 45
Passing grades: [85, 92, 73]

Code Explanation

1. student_grades List:

   • Used to store all student grades.
   • Grades are added using the append() method.

2. add_grade() Function:

   • Takes a grade as input and adds it to the student_grades list.

3. calculate_average() Function:

   • Calculates the class average grade.
   • Uses the sum() function to get the total and len() to count the number of grades.

4. find_max_min() Function:

   • Uses the max() and min() functions to find the highest and lowest grades.

5. list_passing_grades() Function:

   • Uses a list comprehension to filter out all passing grades (≥60).

6. main() Function:

   • Calls the above functions to implement the core logic of the grade management system.

Summary

• This example demonstrates how to use Python's list() to store and manipulate data.
• Lists are highly flexible and ideal for managing dynamic collections of data, such as student grades, task lists, etc.
• By combining list comprehensions and built-in functions like sum(), max(), and min(), you can efficiently perform various data processing tasks.