A Python class-based system for tracking student grades across multiple subjects. Features automatic ID generation, grade management, and statistical calculations.

student.py

class Student:

    students = {}

    def __init__(self, id, name):
        self.id = id
        self.name = name
        self.grades = {}

    def __str__(self):
        """Returns a string representation of the student's id, name and their grades, e.g.:
        'Id: 11001, Name: Alice, Grades: [Math: 2.3, Physics: 3.3, Python: 1.7]'
        """
        grades_list = []

        for subject, grade in self.grades.items():
            grades_list.append(f"{subject}: {grade}")

        grades_str = ", ".join(grades_list)

        return f"Id: {self.id}, Name: {self.name}, Grades: [{grades_str}]"

    def add_grade(self, subject, grade):
        """Adds or updates the grade for a specific subject"""
        self.grades[subject] = grade

    def get_grade(self, subject):
        """Returns the grade for the specified subject or 0.0 if their is no such subject"""
        return self.grades.get(subject, 0.0)

    def get_average_grade(self):
        """Calculates and returns the average grade across all subjects of a student"""
        if len(self.grades) == 0:
            return 0.0

        return sum(self.grades.values()) / len(self.grades)

    @classmethod
    def create(cls, name: str) -> int:
        """Create a new student object with the specified name and an automatically generated id.
        Insert this object into the students dictionary and return the newly generated id.
        """
        new_id = max(cls.students.keys()) + 1 if cls.students else 1
        student = cls(new_id, name)
        cls.students[new_id] = student

        return new_id

    @classmethod
    def get(cls, id):
        """Returns the student object with the specified id, or None if the id does not exist"""
        return cls.students.get(id, None)

    @classmethod
    def delete(cls, id):
        """Removes the Student object with the specified id from the dictionary, only if the student ID exists"""
        if id in cls.students:
            del cls.students[id]

    @classmethod
    def get_average_subject_grade(cls, subject: str) -> float:
        """Calculates and returns the average grade across all students of the specified subject"""
        grades = []
        for student in cls.students.values():
            grade = student.get_grade(subject)
            if grade != 0.0:
                grades.append(grade)

        return sum(grades) / len(grades) if grades else 0.0