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Python – Key Value list pairings in Dictionary

  • Last Updated : 22 Apr, 2020

Sometimes, while working with Python dictionaries, we can have problems in which we need to pair all the keys with all values to form a dictionary with all possible pairings. This can have application in many domains including day-day programming. Lets discuss certain ways in which this task can be performed.

Method #1 : Using list comprehension
This task can be performed using this method. In this we manually extract each key and then iterate with all the values of them to form new dictionary list. This has drawbacks of only available for certain keys.

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# Python3 code to demonstrate working of 
# Key Value list pairings in Dictionary
# Using list comprehension
  
# initializing dictionary
test_dict = {'gfg' : [7, 8],
             'best' : [10, 11, 7]}
  
# printing original dictionary
print("The original dictionary is : " + str(test_dict))
  
# Key Value list pairings in Dictionary
# Using list comprehension
res = [{'gfg': i, 'best': j} for i in test_dict['gfg']
                           for j in test_dict['best']]
  
# printing result 
print("All key value paired List : " + str(res)) 
Output :



The original dictionary is : {‘gfg’: [7, 8], ‘best’: [10, 11, 7]}
All key value paired List : [{‘gfg’: 7, ‘best’: 10}, {‘gfg’: 7, ‘best’: 11}, {‘gfg’: 7, ‘best’: 7}, {‘gfg’: 8, ‘best’: 10}, {‘gfg’: 8, ‘best’: 11}, {‘gfg’: 8, ‘best’: 7}]

 

Method #2 : Using dict() + zip() + product()
The combination of above methods can also be used to perform this task. In this, the formation of combinations is done using product(), and linking of values is done using zip().




# Python3 code to demonstrate working of 
# Key Value list pairings in Dictionary
# Using dict() + zip() + product()
from itertools import product
  
# initializing dictionary
test_dict = {'gfg' : [7, 8],
             'best' : [10, 11, 7]}
  
# printing original dictionary
print("The original dictionary is : " + str(test_dict))
  
# Key Value list pairings in Dictionary
# Using dict() + zip() + product()
res = [dict(zip(test_dict, sub)) for sub in product(*test_dict.values())]
  
# printing result 
print("All key value paired List : " + str(res)) 
Output :

The original dictionary is : {‘gfg’: [7, 8], ‘best’: [10, 11, 7]}
All key value paired List : [{‘gfg’: 7, ‘best’: 10}, {‘gfg’: 7, ‘best’: 11}, {‘gfg’: 7, ‘best’: 7}, {‘gfg’: 8, ‘best’: 10}, {‘gfg’: 8, ‘best’: 11}, {‘gfg’: 8, ‘best’: 7}]




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