python，使用理解选择性地将值从一个字典弹出到另一个字典中

Question

How do I convert this function here into a dictionary comprehension? is it possible?

info['dict1'] = {}
dict2 = {'one': 1}

for x in ['one', 'two']:
    info['dict1'].update({x:dict2.pop(x, None)})

Here is what I tried it didn't work very well, nothing seem to happen. info stays empty:

(info['dict1'].update({x:dict2.pop(x)}) for x in ['one', 'two'])

The print output shows that info stays empty ... {'dict1': {}}

Answer 1

Sure it is:

info['dict1'] = {x: dict2.pop(x, None) for x in ['one', 'two']}

Don't use comprehensions for side effects; they produce a list, set or dictionary first and foremost. In the code above, a new dictionary object for info['dict1'] is produced by a dictionary comprehension.

If you have to update an existing dictionary, use dict.update() with a generator expression producing key-value pairs:

info['dict1'].update((x, dict2.pop(x, None)) for x in ['one', 'two'])

Answer 2

You can create info with dict with the key and use a dict comp ad the value.

dict2 = {'one': 1}
info = {'dict1': {x: dict2.pop(x, None) for x in ['one', 'two']} }
print(info)