Python在'IF'之后的第二条语句上不执行任何操作 [英] Python No Action on 2nd Statement After 'IF'

问题描述

我试图遍历字典并在每个键上调用一个函数.

如果该函数没有为该键返回None条目，则我希望将输出附加到列表中，并且我也希望将该键附加到第二个列表中.

这是我的代码:

    output_list = []
    key_list =[]

    for i in dict.keys():
        if obj.method(i):
            output_list.append(obj.method(i))
            key_list.append(i)

    return output_list
    return key_list

但是，由于某种原因，第二个列表key_list从来没有被填充-您不能像上述那样在if之下有两个语句吗?

执行此操作的原因是，我希望最终产生一个输出，在该输出中，只要输出不是None，该dict的每个键都将与它的关联函数ouput一起列出.

解决方案

key_list正在填充，但是您只能从函数中返回一次.

尽管可以返回多个变量，但是您可以返回结果的元组.更改:

return output_list
return key_list

到

return output_list, key_list

在调用代码中执行:

output_list, key_list = my_function(...)

I am trying to loop over a dictionary and call a function on each key.

If the function does not return None entry for that key, I want the output to be appended to a list and I also want that key to be appended to a second list.

Here is my code:

    output_list = []
    key_list =[]

    for i in dict.keys():
        if obj.method(i):
            output_list.append(obj.method(i))
            key_list.append(i)

    return output_list
    return key_list

However, for some reason the second list, key_list, is never populated - can you not have two statements below an if like the above?

The reason that I am doing this is that I want to eventually produce an output where each key of the dict is listed alongside it's associated function ouput, whenever the output is not None.

解决方案

key_list is being populated, however you can only return once from a function.

You can return a tuple of results though to return multiple variables. Change:

return output_list
return key_list

to

return output_list, key_list

And in the calling code do:

output_list, key_list = my_function(...)

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