Python | Convert nested dictionary into flattened dictionary

Given a nested dictionary, the task is to convert this dictionary into a flattened dictionary where the key is separated by ‘_’ in case of the nested key to be started.

Given below are a few methods to solve the above task.

Method #1: Using Naive Approach

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# Python code to demonstrate
# conversion of nested dictionary
# into flattened dictionary
  
# code to convert ini_dict to flattened dictionary
# default seperater '_'
def flatten_dict(dd, separator ='_', prefix =''):
    return { prefix + separator + k if prefix else k : v
             for kk, vv in dd.items()
             for k, v in flatten_dict(vv, separator, kk).items()
             } if isinstance(dd, dict) else { prefix : dd }
          
# initialising_dictionary
ini_dict = {'geeks': {'Geeks': {'for': 7}},
            'for': {'geeks': {'Geeks': 3}},
            'Geeks': {'for': {'for': 1, 'geeks': 4}}}
  
# priniting initial dictionary
print ("initial_dictionary", str(ini_dict))
  
  
# printing final dictionary
print ("final_dictionary", str(flatten_dict(ini_dict)))

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Output:



initial_dictionary {‘geeks’: {‘Geeks’: {‘for’: 7}}, ‘Geeks’: {‘for’: {‘geeks’: 4, ‘for’: 1}}, ‘for’: {‘geeks’: {‘Geeks’: 3}}}

final_dictionary {‘Geeks_for_for’: 1, ‘geeks_Geeks_for’: 7, ‘for_geeks_Geeks’: 3, ‘Geeks_for_geeks’: 4}





 

Method #2: Using mutuableMapping











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# Python code to demonstrate 


# conversion of nested dictionary 


# into flattened dictionary 


  


from collections import MutableMapping 


  


# code to convert ini_dict to flattened dictionary 


# default seperater '_' 


def convert_flatten(d, parent_key ='', sep ='_'): 


    items = [] 


    for k, v in d.items(): 


        new_key = parent_key + sep + k if parent_key else k 


  


        if isinstance(v, MutableMapping): 


            items.extend(convert_flatten(v, new_key, sep = sep).items()) 


        else: 


            items.append((new_key, v)) 


    return dict(items) 


          


# initialising_dictionary 


ini_dict = {'geeks': {'Geeks': {'for': 7}}, 


            'for': {'geeks': {'Geeks': 3}}, 


            'Geeks': {'for': {'for': 1, 'geeks': 4}}} 


  


# priniting initial dictionary 


print ("initial_dictionary", str(ini_dict)) 


  


  


# printing final dictionary 


print ("final_dictionary", str(convert_flatten(ini_dict))) 



















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Output:



initial_dictionary {‘Geeks’: {‘for’: {‘for’: 1, ‘geeks’: 4}}, ‘for’: {‘geeks’: {‘Geeks’: 3}}, ‘geeks’: {‘Geeks’: {‘for’: 7}}}

final_dictionary {‘Geeks_for_geeks’: 4, ‘for_geeks_Geeks’: 3, ‘geeks_Geeks_for’: 7, ‘Geeks_for_for’: 1}





 

Method #3: Using Python Generators 











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# Python code to demonstrate 


# conversion of nested dictionary 


# into flattened dictionary 


  


def flattenit(pyobj, keystring =''): 


   if type(pyobj) is dict: 


     if (type(pyobj) is dict): 


         keystring = keystring + "_" if keystring else keystring 


         for k in pyobj: 


             yield from flattenit(pyobj[k], keystring + k) 


  


     elif (type(pyobj) is list): 


         for lelm in pyobj: 


             yield from flatten(lelm, keystring) 


   else: 


      yield keystring, pyobj 


          


# initialising_dictionary 


ini_dict = {'geeks': {'Geeks': {'for': 7}}, 


            'for': {'geeks': {'Geeks': 3}}, 


            'Geeks': {'for': {'for': 1, 'geeks': 4}}} 


  


# priniting initial dictionary 


print ("initial_dictionary", str(ini_dict)) 


  


# code to convert ini_dict to flattened dictionary 


res = {k:v for k, v in flattenit(ini_dict)} 


  


# printing final dictionary 


print ("final_dictionary", str(res)) 



















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Output:



initial_dictionary {‘for’: {‘geeks’: {‘Geeks’: 3}}, ‘geeks’: {‘Geeks’: {‘for’: 7}}, ‘Geeks’: {‘for’: {‘for’: 1, ‘geeks’: 4}}}

final_dictionary {‘Geeks_for_geeks’: 4, ‘for_geeks_Geeks’: 3, ‘Geeks_for_for’: 1, ‘geeks_Geeks_for’: 7}






          
          
          
          

            

    

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