列表索引必須是整數不str的蟒蛇錯誤

Question

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] 
} 

# Add your function below! 

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

def get_average(student): 
    homework=average(student["homework"]) 
    quizzes=average(student["quizzes"]) 
    tests=average(student["tests"]) 
    print student["name"] 
    return .1*homework+.3*quizzes+.6*tests 

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" 

results=[] 

def get_class_average(students): 
    results.append(get_average(students)) 
    return average(results) 



qq=[lloyd,alice,tyler] 


for x in qq: 
    get_class_average(x) 
    s= get_average(x) 
    print s, get_letter_grade(s) 
    print 

print results , "Total class average is %s" % average(results) 

＃

上述方案雖然給予正確的結果是給我下面的錯誤： get_class_average（[愛麗絲]）導致錯誤：列表索引必須是整數，不str的

輸出如下：

Lloyd 
Lloyd 
80.55 B 

Alice 
Alice 
91.15 A 

Tyler 
Tyler 
79.9 C 

[80.55, 91.14999999999999, 79.9] Total class average is 83.8666666667 
None 

Answer 1

你可能想什麼是平均超過所有的學生，如：

def get_class_average(students): 
    student_averages = list(get_average(student) for student in students) 
    return average(student_averages) 

get_class_average(qq) 

其中產出：

Lloyd 
Alice 
Tyler 
83.86666666666666 

所以，問題是你的get_class_average實現。

更新：

您的代碼可以更加簡化：

results = [get_average(student) for student in qq] 
print results , "Total class average is %s" % average(results)