How to exchange values between specific keys in a dictionary?

问题

Let's say you have a dictionary like this:

d = {
    'A': 'content_for_A',
    'B': 'content_for_B'
}

What is the most efficient way to swap the values between the two entries? So the result should be like this:

d = {
    'A': 'content_for_B',
    'B': 'content_for_A'
}

Of course, you can create a new dictionary d2 and do d2['A'] = d['B']; d2['B'] = d['A'] but is this the recommended way or is there an efficient way without the need to create a new dictionary?

回答1:

d['A'], d['B'] = d['B'], d['A']

Tuple unpacking is a great tool in Python to swap the values of two objects without the need of creating an intermediary variable.

来源：https://stackoverflow.com/questions/14830555/how-to-exchange-values-between-specific-keys-in-a-dictionary