Python implements the exchange of keys and values of a dictionary

There are times when we have to use values to reverse query key, is there a simple way?

I will give you some examples of ways to facilitate the use of people

Python3

>>> d1={' A ': 1, ' B ':2}>>> {Value:key for key,value in D1.iteritems ()}{1: ' A ', 2: ' B '}>>> {value : Key for Key,value in D1.iteritems ()}[2] ' B '

python2.7

>>> d1={' A ': 1, ' B ':2}>>> dict ((value,key) for Key,value in D1.iteritems ()) {1: ' A ', 2: ' B '}

If there is a duplicate key

>>> d1={' A ': 1, ' B ': 2, ' C ':1}>>> d=defaultdict (list) >>> for k,v in D1.iteritems ():   ... D[v].append (k) ... >>> ddefaultdict (
 
 
  
  , {1: [' A ', ' C '], 2: [' B ']})
 
 

Keith, too good .....

Thanks to the help of the great God of the line-speakers

The above is the whole content of this article, I hope to learn Python can help you.

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