CRUD, mean, std deviation subject - student

assignment2.py

import math

class ClassRoom:
    students = { }
    mean = 0
    stdDeviation = 0

    def get_total_students(self):
        return len(self.students)
    
    def get_all_students(self):
        return self.students.items()
    
    def get_mean_score(self):
        total = 0
        for usn in self.students.keys():
            total += self.students[usn]['score']
        self.mean = total / len(self.students)
        return self.mean

    def get_std_deviation(self):
        total = 0
        for usn in self.students:
            total += math.pow(self.students[usn]['score'] - self.mean, 2)
        self.stdDeviation = math.sqrt(total/len(self.students))
        return self.stdDeviation
        
    def create_student(self, name, usn, score):
        if name != '' or usn != '' or not (score < 0 and score > 100): 
            student = { 'name': name, 'score': score }
            self.students[usn] = student
            print "Created: Student record for usn: ", usn, student
        else:
            print "Invalid input: Record creation failed"

    def get_student_info(self, usn):
        if usn != '' and self.students.has_key(usn):
            print "Get usn: ", usn, self.students[usn]
        else:
            return "No student record found for usn: ", usn
    
    def update_student_info(self, usn, name, score):
        if usn != '' and self.students.has_key(usn):
            if name != '' or not (score < 0 and score > 100):
                student = { 'name': name, 'score': score }
                self.students[usn] = student
                print "Updated: Student record for usn: ", usn, student
        else:
            return "No student record found for usn: ", usn
    
    def delete_student_info(self, usn):
        if usn != '' and self.students.has_key(usn):
            record = self.students.get(usn)
            del self.students[usn]
            print "Deleted: Student record ", usn, record
        else:
            return "No student record found for usn: ", usn

def main():
    c = ClassRoom()
    c.create_student("Sona1", "12341", 45)
    c.create_student("Sona2", "12342", 44)
    c.create_student("Sona3", "12343", 43)
    c.create_student("Sona4", "12344", 42)
    c.create_student("Sona5", "12345", 41)
    
    print "All student info, ", c.get_all_students()
    print "Total number of students: ", c.get_total_students()
    
    print "Mean Score: ", c.get_mean_score()
    print "Standard Deviation: ", c.get_std_deviation()
    
    c.get_student_info("12341")
    c.delete_student_info("12345")
    print "Total number of students: ", c.get_total_students()

if __name__ == "__main__":
    main()