Python 值错误 : too many values to unpack (For loop with nested variable)

Question

我有以下代码:

col_cp1_tariff_time_weekday_1_hour = 0
col_cp1_tariff_time_weekday_2_hour = 7
col_cp1_tariff_time_weekday_3_hour = 9
col_cp1_tariff_time_weekday_4_hour = 19
col_cp1_tariff_time_weekday_5_hour = 21


weekday_cents_questions = [
    "What is the tariff from the weekday time %d:00? (in cents e.g 23.5)\n" % (col_cp1_tariff_time_weekday_1_hour),
    "What is the tariff from the weekday time %d:00? (in cents e.g 23.5)\n" % (col_cp1_tariff_time_weekday_2_hour),
    "What is the tariff from the weekday time %d:00? (in cents e.g 23.5)\n" % (col_cp1_tariff_time_weekday_3_hour),
    "What is the tariff from the weekday time %d:00? (in cents e.g 23.5)\n" % (col_cp1_tariff_time_weekday_4_hour),
    "What is the tariff from the weekday time %d:00? (in cents e.g 23.5)\n" % (col_cp1_tariff_time_weekday_5_hour)]


print("You will now be asked to enter the cost per kWh for the hourly times in a 24 hour clock.")

variable_bands = [0]

for question in weekday_cents_questions:
    try:
        q = question.format(variable_bands[-1])
        cents = int(input(q))
        variable_bands.append(cents)
    except (SyntaxError, ValueError):
        variable_bands.append(0)

[col_cp1_tariff_time_weekday_1_cents,
 col_cp1_tariff_time_weekday_2_cents,
 col_cp1_tariff_time_weekday_3_cents,
 col_cp1_tariff_time_weekday_4_cents,
 col_cp1_tariff_time_weekday_5_cents] = variable_bands

print(variable_bands)

当我执行时，我收到错误: ValueError:要解压的值太多(预期为 5)

你能告诉我如何修复吗？我正在尝试将输入的整数分配给 variable_band 变量。

Answer 1

从 variable_bands = [0] 行开始，此列表的大小已经 1。然后，您的代码将另外五个元素附加到 variable_bands，导致此列表的大小为 6，因此出现 ValueError。

相反，将 variable_bands = [0] 更改为 variable_bands = []。

但是，在更改之后，您还必须从 for question in weekday_cents_questions: 查看所有 try-except block ，它仍然无法工作，因为当列表是空的，你想得到最后一个列表，它仍然是一个数组索引超出范围的回溯。相反，您必须删除 question.format() 部分，因为它不是必需的。

你的最终代码应该是

variable_bands = []

for question in weekday_cents_questions:
    try:
        cents = int(input(question))
        variable_bands.append(cents)
    except (SyntaxError, ValueError):
        variable_bands.append(0)

这是修改后程序的运行示例

You will now be asked to enter the cost per kWh for the hourly times in a 24 hour clock.
What is the tariff from the weekday time 0:00? (in cents e.g 23.5)
1
What is the tariff from the weekday time 7:00? (in cents e.g 23.5)
2
What is the tariff from the weekday time 9:00? (in cents e.g 23.5)
3
What is the tariff from the weekday time 19:00? (in cents e.g 23.5)
omg
What is the tariff from the weekday time 21:00? (in cents e.g 23.5)
4
[1, 2, 3, 0, 4]