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Python – Combine dictionary with priority
  • Last Updated : 10 May, 2020

Sometimes, while working with dictionary data, we can have problem in which we need to combine two dictionaries. This is very common problem. But a variation of this can be combining dictionaries, and giving precedence to a particular dictionary if both the keys clash in dictionaries. Let’s discuss certain ways in which this task can be performed.

Input : test_dict1 = {‘Gfg’ : 6, ‘is’ : 15, ‘best’ : 13}
test_dict2 = {‘Gfg’ : 8, ‘is’ : 10}
Output : {‘Gfg’: 8, ‘best’: 13, ‘is’: 10}

Input : test_dict1 = {‘Gfg’ : 6}
test_dict2 = {‘Gfg’ : 8}
Output : {‘Gfg’: 8}

Method #1 : Using copy() + loop
The combination of above functionalities can be used to solve this problem. This is brute way in which this problem can be solved. In this, we perform copy() to deep copy dictionary values and then override the values using priority dictionary.




# Python3 code to demonstrate working of 
# Combine dictionary with priority
# Using loop + copy()
  
# initializing dictionaries
test_dict1 = {'Gfg' : 1, 'is' : 2, 'best' : 3}
test_dict2 = {'Gfg' : 4, 'is' : 10, 'for' : 7, 'geeks' : 12}
  
# printing original dictionaries
print("The original dictionary is 1 : " + str(test_dict1))
print("The original dictionary is 2 : " + str(test_dict2))
  
# declaring priority order
prio_dict = {1 : test_dict2, 2: test_dict1}
  
# Combine dictionary with priority
# Using loop + copy()
res = prio_dict[2].copy()
for key, val in prio_dict[1].items():
    res[key] = val
      
# printing result 
print("The dictionary after combination : " + str(res)) 
Output :



The original dictionary is 1 : {‘is’: 2, ‘best’: 3, ‘Gfg’: 1}
The original dictionary is 2 : {‘for’: 7, ‘is’: 10, ‘geeks’: 12, ‘Gfg’: 4}
The dictionary after combination : {‘for’: 7, ‘is’: 10, ‘best’: 3, ‘geeks’: 12, ‘Gfg’: 4}

 

Method #2 : Using ** operator
This is a new method to solve this problem, we can bind both dictionaries, the dictionary bound at second place takes priority over keys of initial dictionary.




# Python3 code to demonstrate working of 
# Combine dictionary with priority
# Using ** operator
  
# initializing dictionaries
test_dict1 = {'Gfg' : 1, 'is' : 2, 'best' : 3}
test_dict2 = {'Gfg' : 4, 'is' : 10, 'for' : 7, 'geeks' : 12}
  
# printing original dictionaries
print("The original dictionary is 1 : " + str(test_dict1))
print("The original dictionary is 2 : " + str(test_dict2))
  
# declaring priority order
prio_dict = {1 : test_dict2, 2: test_dict1}
  
# Combine dictionary with priority
# Using ** operator
res = {**prio_dict[2], **prio_dict[1]} 
      
# printing result 
print("The dictionary after combination : " + str(res)) 
Output :

The original dictionary is 1 : {‘is’: 2, ‘best’: 3, ‘Gfg’: 1}
The original dictionary is 2 : {‘for’: 7, ‘is’: 10, ‘geeks’: 12, ‘Gfg’: 4}
The dictionary after combination : {‘for’: 7, ‘is’: 10, ‘best’: 3, ‘geeks’: 12, ‘Gfg’: 4}

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