python - 一次替换列表中的项目

Question

我正在尝试为我正在学习的 Python 类(class)编写“填空”。我才刚刚开始，我遇到了一些我不太明白的事情。

这是主要的代码块:

easy = ['In ','___(1)___',' if you want to pass the W3 validator, make sure you close your ','___(2)___','!']

easy_list = ['HTML','tags']
blank_list = ['___(1)___','___(2)___','___(3)___','___(4)___','___(5)___','___(6)___']

def num_replace(level,word):
    new_level = []
    for i in level:
        if i == blank_list[word]:
            new_level[word] = easy_list[word]
        else:
            new_level.append(i)
    return new_level

我试过将函数输出为像这样的简单打印:

print ''.join(num_replace(easy,0))
print ''.join(num_replace(easy,1))

但我会得到的是:

HTML if you want to pass the W3 validator, make sure you close your ___(2)___!

然后……

In tags if you want to pass the W3 validator, make sure you close your !

所以我尝试这样输出它:

happy_list = ''.join(num_replace(easy,0))
print happy_list
happy_list = ''.join(num_replace(easy,1))
print happy_list

但我得到了同样的结果。

澄清我想要得到的是:

在调用 num_replace 之前:在 ___(1)___ 中，如果您想通过 W3 验证程序，请确保关闭您的 ___(2)___!

num_replace(easy,0) 应该输出:在 HTML 中如果你想通过 W3 验证器，确保你关闭你的 ___(2)___!

num_replace(easy,1): 在 HTML 中，如果你想通过 W3 验证器，请确保关闭你的标签!

Answer 1

这里有两个问题:

1 - 您正在将新词附加到第 word 位置。 new_level[word] = append(easy_list[word])2 - 您没有将更改保存到新字符串，因为字符串是不可变的。所以这里是变化:

>>> def num_replace(level, word):
        new_level = []
        for i in level:
            if i == blank_list[word]:
                new_level.append(easy_list[word])
            else:
                new_level.append(i)
        return new_level

>>> 
>>> 
>>> ''.join(num_replace(easy,0))
'In HTML if you want to pass the W3 validator, make sure you close your ___(2)___!'
>>> ''.join(num_replace(easy,1))
'In ___(1)___ if you want to pass the W3 validator, make sure you close your tags!'
>>> 

现在，您必须以这种方式保存所做的更改:

>>> l = num_replace(easy,0)
>>> l
['In ', 'HTML', ' if you want to pass the W3 validator, make sure you close your ', '___(2)___', '!']
>>> 
>>> ''.join(num_replace(l,1))
'In HTML if you want to pass the W3 validator, make sure you close your tags!'
>>> 

或者如果你想在一行中:

>>> ''.join(num_replace(num_replace(easy,0),1))
'In HTML if you want to pass the W3 validator, make sure you close your tags!'