Python中的“无法与非整数相乘-浮点数”错误

Question

lloyd = {    "name": "Lloyd",    "homework": [90, 97, 75, 92],    "quizzes": [88, 40, 94],    "tests": [75, 90]}alice = {    "name": "Alice",    "homework": [100, 92, 98, 100],    "quizzes": [82, 83, 91],    "tests": [89, 97]}tyler = {    "name": "Tyler",    "homework": [0, 87, 75, 22],    "quizzes": [0, 75, 78],    "tests": [100, 100]}def get_average(student):    weight = 0    total = 0    for item in student:        if item == "homework":            weight = .1        elif item == "quizzes":            weight = .3        elif item == "tests":            weight = .6        else:            weight = 0        total += student[item] * weight    return totalget_average(tyler)这里发生了什么？这给我一个错误，说student[item] 无法与非整数相乘-浮点数

Answer 1

您正在尝试将字符串和列表与浮点数相乘，这是不可能的。

student[item] * weight

尝试这样的事情：

def get_average(student):

    weight = 0

    total = 0

    for item,val in student.items(): #use dict.items() if you need to wrk on both key and values

        if item == "homework":

            weight = .1

        elif item == "quizzes":

            weight = .3

        elif item == "tests":

            weight = .6

        else:

            continue    # no need of weight = 0 simple move on to next item

                        # continue statement jumps the loop to next iteration

        total += (float(sum(val)) / len(val)) * weight

    return total

print get_average(tyler)  #prints 79.9

Answer 2

由于您无法将列表乘以权重，因此请先获取平均值！在for循环中添加以下行：

averaged = sum(student[item])/float(len(student[item]))

total += averaged * weight

所以现在这是您的for循环：

for item in student:

        if item != "Name":

            averaged = sum(student[item])/float(len(student[item]))

        if item == "homework":

            weight = .1

        elif item == "quizzes":

            weight = .3

        elif item == "tests":

            weight = .6

        else:

            weight = 0

        total += averaged * weight