This python recursive function flattens a JSON file or a dictionary with nested lists and/or dictionaries. The output is a flattened dictionary that use dot-chained names for keys, based on the dictionary structure. This allows for reconstructing the JSON structure or converting it to other formats without loosing any structural information.

Flatten JSON or a nested dictionary

"""
example: The following JSON document:  
{"maps":[{"id1":"blabla","iscategorical1":"0", "perro":[{"dog1": "1", "dog2": "2"}]},{"id2":"blabla","iscategorical2":"0"}],
"masks":{"id":"valore"},
"om_points":"value",
"parameters":{"id":"valore"}}

will have the following output:
{'masks.id': 'valore', 'maps.iscategorical2': '0', 'om_points': 'value', 'maps.iscategorical1': '0', 
'maps.id1': 'blabla', 'parameters.id': 'valore', 'maps.perro.dog2': '2', 'maps.perro.dog1': '1', 'maps.id2': 'blabla'}
"""

def flattenDict(d, result=None):
    if result is None:
        result = {}
    for key in d:
        value = d[key]
        if isinstance(value, dict):
            value1 = {}
            for keyIn in value:
                value1[".".join([key,keyIn])]=value[keyIn]
            flattenDict(value1, result)
        elif isinstance(value, (list, tuple)):   
            for indexB, element in enumerate(value):
                if isinstance(element, dict):
                    value1 = {}
                    index = 0
                    for keyIn in element:
                        newkey = ".".join([key,keyIn])        
                        value1[".".join([key,keyIn])]=value[indexB][keyIn]
                        index += 1
                    for keyA in value1:
                        flattenDict(value1, result)   
        else:
            result[key]=value
    return result