使用Python计算学生/班级平均分

Question

python 3.3.3

我正在为课堂写一个程序，但我有点迷茫。以下是我需要做的事情。

我需要根据输入的成绩来计算每个学生的平均分。
我还需要计算全班的平均分。
如果某个学生输入的成绩是-1，那么就停止输入成绩。
我需要打印出每个学生的成绩信息。
学生的成绩应该显示一个数字成绩和一个字母成绩。
这个信息会根据学生的字母成绩来决定。

我该如何收集和存储学生的姓名和考试成绩，
这样我就可以一次性输出所有信息，包括学生的姓名、
他们的数字平均分、根据这个平均分得出的字母成绩，
以及根据他们获得的字母成绩给出的评语？

这是我目前写的代码：

def main():
    another_student = 'y'
    while another_student == 'y' or another_student == 'Y':
        student_average()
        print()
        another_student = input('do you have another student to enter (y/n) ? ')
    while another_student == 'n' or another_student == 'N':
        student_average_list()
        class_average()
        break

def student_average():
    total = 0.0
    print()
    student_name = input('what is the students name? ')
    print()
    print()
    print(student_name)
    print('-------------------')
    number_of_tests = int(input('please enter the number of tests : '))
    for test_num in range(number_of_tests):
        print('test number', test_num + 1, end='')
        score = float(input(': '))
        total += score
    student_average = total / number_of_tests
    print ()
    print(student_name,"'s average is : ",student_average, sep='')

def student_average_list():
    print ('kahdjskh')

def class_average():
    print ('alsjd')

main()

Answer 1

你需要记录整个班级的成绩。现在的 student_average 函数做的事情太多了。或许可以创建一个 get_student_marks 函数，专门用来返回某个学生的成绩列表。你还需要一个 average 函数，用来计算一个列表的平均值，这样就可以同时用来计算学生的平均分和班级的平均分。祝你好运！

Answer 2

我觉得这段内容差不多就是你想要的。它定义了一个Student类，这样可以让数据的存储和处理变得更简单一些。

class Student(object):
    def __init__(self, name):
        self.name, self.grades = name, []

    def append_grade(self, grade):
        self.grades.append(grade)

    def average(self):
        return sum(self.grades) / len(self.grades)

    def letter_grade(self):
        average = self.average()
        for value, grade in (90, "A"), (80, "B"), (70, "C"), (60, "D"):
            if average >= value:
                return grade
        else:
            return "F"

def main():
    print()
    print('Collecting class student information')
    a_class = []  # "class" by itself is a reserved word in Python, avoid using
    while True:
        print()
        print('{} students in class so far'.format(len(a_class)))
        another_student = input('Do you have another student to enter (y/n) ? ')
        if another_student[0].lower() != 'y':
            break
        print()
        student_name = input('What is the student\'s name? ')
        a_class.append(Student(student_name))
        print()
        print('student :', student_name)
        print('-------------------')
        number_of_tests = int(input('Please enter the number of tests : '))
        for test_num in range(1, number_of_tests+1):
            print('test number {}'.format(test_num), end='')
            score = float(input(' : '))
            if score < 0:  # stop early?
                break
            a_class[-1].append_grade(score) # append to last student added

    print_report(a_class)

def print_report(a_class):
    print()
    print('Class Report')
    print()
    for student in sorted(a_class, key=lambda s: s.name):
        print('student: {:20s} average test score: {:3.2f}  grade: {}'.format(
            student.name, student.average(), student.letter_grade()))
    print()
    print('The class average is {:.2f}'.format(class_average(a_class)))

def class_average(a_class):
    return sum(student.average() for student in a_class) / len(a_class)

main()