按课程列出
本课属于 Coddy Python 学习旅程的“逻辑与流程”单元。第 44 课，共 78 课。
挑战
简单保留你在这个项目前面步骤中编写的所有内容：运行的是整个文件，所以 student_records 和 add_student 必须仍然保留。
创建一个名为 list_students_by_course 的函数，它接受一个参数：course（字符串）。该函数应当：
- 遍历
student_records字典，找出所有选修指定course的学生。 - 返回选修该课程的学生姓名列表。
- 如果没有学生选修该课程，则返回一个空列表。
在代码底部添加（替换为）以下代码块：
add_student("Alice", 20, ["Math", "Physics"])
add_student("Bob", 22, ["Math", "Biology"])
add_student("Diana", 23, ["Chemistry", "Physics"])
print(list_students_by_course("Math")) # Should return ["Alice", "Bob"]
print(list_students_by_course("Physics")) # Should return ["Alice", "Diana"]
print(list_students_by_course("Biology")) # Should return ["Bob"]
print(list_students_by_course("History")) # Should return an empty list亲手试试
student_records = {}
def add_student(name, age, courses):
if name in student_records:
print(f"Student '{name}' already exists.")
return
student_records[name] = {"age": age, "grades": set(), "courses": set(courses)}
print(f"Student '{name}' added successfully.")
def add_grade(name, grade):
if name not in student_records:
print(f"Student '{name}' not found.")
return
student_records[name]["grades"].add(grade)
print(f"Grade {grade} added for student '{name}'.")
def is_enrolled(name, course):
if name not in student_records:
print(f"Student '{name}' not found.")
return False
return course in student_records[name]["courses"]
def calculate_average_grade(name):
if name not in student_records:
print(f"Student '{name}' not found.")
return None
grades = student_records[name]["grades"]
if not grades:
return 0
return sum(grades) / len(grades)
add_student("Alice", 20, ["Math", "Physics"])
add_student("Bob", 22, ["Biology", "Chemistry"])
add_grade("Alice", 90)
add_grade("Alice", 85)
add_grade("Bob", 75)
print(calculate_average_grade("Alice")) # Should return 87.5
print(calculate_average_grade("Bob")) # Should return 75.0
print(calculate_average_grade("Charlie")) # Non-existent student, should print message and return None
print(calculate_average_grade("Alice")) # Should return 87.5 again逻辑与流程中的所有课
自己练习： Python 在线编译器