Python – Remove unwanted Keys associations

Sometimes, while working with Python dictionaries, we can have problem in which we need to remove some unwanted keys and its associated nestings. This can have application across many domains including web development and competitive programming. Let’s discuss certain ways in which this task can be performed.

Input : test_dict = {‘best’ : {‘for’ : {‘geeks’ : {‘CS’ : {‘Gfg’ : 12}}}}}
Output : {‘best’: {‘for’: {}}}

Input : test_dict = {‘best’ : 14, ‘gfg’ : 13}
Output : {‘best’ : 14, ‘gfg’ : 13}

Method #1 : Using isinstance() + loop + recursion
The combination of above functionalities can be used to solve this problem. In this, we check for the element value being a dictionary or key using isinstance() and we recur for the construction of all the keys that are not present as unwanted keys.

# Python3 code to demonstrate working of
# Remove unwanted Keys associations
# Using isinstance() + loop + recursion

def helper_fnc(test_dict, unw_keys):
    temp = {}
    for key, val in test_dict.items():
        if key in unw_keys:
            continue
        if isinstance(val, dict):
            temp[key] = helper_fnc(val, unw_keys)
        else:
            temp[key] = val
    return temp

# initializing dictionary
test_dict = {"Gfg" : {'is' : 45, 'good' : 15},
             'best' : {'for' : {'geeks' :  {'CS' : 12}}}}

# printing original dictionary
print("The original dictionary : " + str(test_dict))

# initializing unwanted keys
unw_keys = ['is', 'geeks']

# Remove unwanted Keys associations
# Using isinstance() + loop + recursion
res = helper_fnc(test_dict, unw_keys)

# printing result
print("The filtered dictionary : " + str(res))

Output :

The original dictionary : {‘Gfg’: {‘is’: 45, ‘good’: 15}, ‘best’: {‘for’: {‘geeks’: {‘CS’: 12}}}}
The filtered dictionary : {‘Gfg’: {‘good’: 15}, ‘best’: {‘for’: {}}}