Python – Remove K valued key from Nested Dictionary

Last Updated : 14 May, 2020

Sometimes, while working with records, we can have a problem in which we need to perform the removal of a key from nested dictionary whose value us specific to K. This is a common problem and has its application in data domains such as web development. Lets discuss certain ways in which this task can be performed.

Input : test_dict = {‘CS’: {‘priceless’: 6}, ‘is’: {‘better’: 6}, ‘gfg’: {‘best’: 6}}
Output : {‘CS’: {}, ‘gfg’: {}, ‘is’: {}}
Input : test_dict = {‘CS’: {‘priceless’: 9}, ‘is’: {‘better’: 8}, ‘gfg’: {‘best’: 7}}
Output : {‘CS’: {‘priceless’: 9}, ‘is’: {‘better’: 8}, ‘gfg’: {‘best’: 7}}

Method #1 : Using loop + isinstance() + filter()
The combination of above functions can be used to solve this problem. In this, we perform the task of K value using filter() and isinstance() is used to test for nesting dictionary. The dictionary construction is done using loop.

# Python3 code to demonstrate working of 
# Remove K valued key from Nested Dictionary
# Using loop + isinstance() + filter()
  
# initializing dictionary
test_dict = {'gfg' : {'best' : 4, 'good' : 5}, 
             'is' : {'better' : 6, 'educational' : 4},
             'CS' : {'priceless' : 6}}
  
# printing original dictionary
print("The original dictionary : " + str(test_dict))
  
# initializing rem_val
rem_val = 6
  
# Remove K valued key from Nested Dictionary
# Using loop + isinstance() + filter()
def rem_vals(ele):
  global rem_val
  key, val = ele
  return val != rem_val
  
res = dict()
for key, val in test_dict.items():
  if isinstance(val, dict):
    res[key] = dict(filter(rem_vals, val.items()))
  else:
    res[key] = val
  
# printing result 
print("Dictionary after removal : " + str(res)) 

Output :

The original dictionary : {‘is’: {‘educational’: 4, ‘better’: 6}, ‘gfg’: {‘best’: 4, ‘good’: 5}, ‘CS’: {‘priceless’: 6}}
Dictionary after removal : {‘is’: {‘educational’: 4}, ‘gfg’: {‘best’: 4, ‘good’: 5}, ‘CS’: {}}

Method #2 : Using dictionary comprehension + isinstance() + lamda
The combination of above functionalities can be used to perform this task in one liner using lambda function.

# Python3 code to demonstrate working of 
# Remove K valued key from Nested Dictionary
# Using dictionary comprehension + isinstance() + lamda
  
# initializing dictionary
test_dict = {'gfg' : {'best' : 4, 'good' : 5}, 
             'is' : {'better' : 6, 'educational' : 4},
             'CS' : {'priceless' : 6}}
  
# printing original dictionary
print("The original dictionary : " + str(test_dict))
  
# initializing rem_val
rem_val = 6
  
# Remove K valued key from Nested Dictionary
# Using dictionary comprehension + isinstance() + lamda
fnc = lambda sub: { key1: fnc(val1) if isinstance(val1, dict) else val1
      for key1, val1 in sub.items() if val1 != rem_val}
res = fnc(test_dict)
  
# printing result 
print("Dictionary after removal : " + str(res)) 

Output :

The original dictionary : {‘is’: {‘educational’: 4, ‘better’: 6}, ‘gfg’: {‘best’: 4, ‘good’: 5}, ‘CS’: {‘priceless’: 6}}
Dictionary after removal : {‘is’: {‘educational’: 4}, ‘gfg’: {‘best’: 4, ‘good’: 5}, ‘CS’: {}}

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Python – Remove K valued key from Nested Dictionary