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Python – Sorted Nested Keys in Dictionary
  • Last Updated : 14 May, 2020

Sometimes, while working with Python dictionaries, we can have a problem in which we need to extract all the keys of nested dictionaries and render them in sorted order. This kind of application can occur in domains in which we work with data. Lets discuss certain ways in which this task can be performed.

Method #1 : Using yield + isinstance() + loop
The combination of above functions can be used to perform this task. In this, we perform the task of detection of keys using isinstance(). The yield keyword is used to add intermediate results.




# Python3 code to demonstrate working of 
# Sorted Nested Keys in Dictionary
# Using yield + isinstance() + loop
  
def hlper_fnc(test_dict):
     for key, val in test_dict.items():
         yield key
         if isinstance(val, dict):
             yield from val
  
# initializing dictionary
test_dict = {'gfg': 43, 'is': {'best' : 14, 'for' : 35, 'geeks' : 42}, 'and' : {'CS' : 29}}
  
# printing original dictionary
print("The original dictionary is : " + str(test_dict))
  
# Sorted Nested Keys in Dictionary
# Using yield + isinstance() + loop
res = sorted(hlper_fnc(test_dict))
      
# printing result 
print("The sorted nested keys : " + str(res)) 
Output :

The original dictionary is : {‘and’: {‘CS’: 29}, ‘gfg’: 43, ‘is’: {‘for’: 35, ‘best’: 14, ‘geeks’: 42}}
The sorted nested keys : [‘CS’, ‘and’, ‘best’, ‘for’, ‘geeks’, ‘gfg’, ‘is’]

 



Method #2 : Using sorted() + list comprehension + isinstance()
The combination of above functions offer a shorthand solution to this problem. In this, the sorting is done using sorted(). The isinstance() is used to detect keys.




# Python3 code to demonstrate working of 
# Sorted Nested Keys in Dictionary
# Using sorted() + list comprehension + isinstance()
  
# initializing dictionary
test_dict = {'gfg': 43, 'is': {'best' : 14, 'for' : 35, 'geeks' : 42}, 'and' : {'CS' : 29}}
  
# printing original dictionary
print("The original dictionary is : " + str(test_dict))
  
# Sorted Nested Keys in Dictionary
# Using sorted() + list comprehension + isinstance()
res = sorted([key for val in test_dict.values() if isinstance(val, dict)
             for key in val] + list(test_dict))
      
# printing result 
print("The sorted nested keys : " + str(res)) 
Output :

The original dictionary is : {‘and’: {‘CS’: 29}, ‘gfg’: 43, ‘is’: {‘for’: 35, ‘best’: 14, ‘geeks’: 42}}
The sorted nested keys : [‘CS’, ‘and’, ‘best’, ‘for’, ‘geeks’, ‘gfg’, ‘is’]

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