Question

我正在尝试用Python编写一个平均成绩计算器，用于CodeAcademy课程。我一直收到这个错误

TypeError: unsupported operand type(s) for +: 'int' and 'NoneType'

关于平均函数total = sum(numbers)。我理解这意味着我试图将两种不同的类型相加，这是不可能的。但是我不知道这个NoneType来自哪里，如果我试图只从给定字典中加入一个数字列表？

此外，编写此代码的更好方法是什么？我假设有更简单的方法可以完全相同。

lloyd = {  
  "name": "Lloyd",  
  "homework": [90.0, 97.0, 75.0, 92.0],  
  "quizzes": [88.0, 40.0, 94.0],  
  "tests": [75.0, 90.0]  
}  
alice = {  
  "name": "Alice",   
  "homework": [100.0, 92.0, 98.0, 100.0],  
  "quizzes": [82.0, 83.0, 91.0],  
  "tests": [89.0, 97.0]
}  
tyler = {
  "name": "Tyler",  
  "homework": [0.0, 87.0, 75.0, 22.0],  
  "quizzes": [0.0, 75.0, 78.0],  
  "tests": [100.0, 100.0]  
}    
class_list = [lloyd, alice, tyler]  
students = [lloyd, alice, tyler]  

# Add your function below!


def average(numbers):    
  total = sum(numbers)  
  averege_grade =  float(total)/len(numbers)  
  return averege_grade  

def get_average(student):  
    homework = average(student["homework"])  
    quizzes = average(student["quizzes"])  
    tests = average(student["tests"])  
    total_average = float(homework) * 1 + float(quizzes) * 3 + float(tests) * 6  

def  get_letter_grade(score):  
  if score >= 90:  
    return "A"  
  elif score >= 80:  
    return "B"  
  elif score >= 70:  
    return "C"  
  elif score >= 60:  
    return "D"  
  else:   
    return "F"  

def get_class_average(class_list):  
    results = []  
    for student in class_list:  
        resultadinho = get_average(student)  
        results.append(resultadinho)  
        return average(results)  
print get_class_average(students)  
print get_letter_grade

Answer 1

您未从get_average()返回任何内容，因此当sum启动时（使用0作为第一个累积值，它会尝试添加None和{{ 1}}解释了错误信息。

TypeError：+：＆＃39; int＆＃39;不支持的操作数类型和＆＃39; NoneType＆＃39;总结清单时

1 个答案: