Python - Remove K valued key from Nested Dictionary

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’: {}}

Attention geek! Strengthen your foundations with the Python Programming Foundation Course and learn the basics.

To begin with, your interview preparations Enhance your Data Structures concepts with the Python DS Course.

My Personal Notes

Related Articles