Merge two dictionaries and keep the values for duplicate keys in Python

Question

Let\'s suppose that I have two dictionaries:

dic1 =  { \"first\":1, \"second\":4, \"third\":8} 
dic2 =  { \"first\":9, \"second\":5, \"fourth\":3}

Answer 1

from copy import deepcopy


def _add_value_to_list(value, lis):
    if value:
        if isinstance(value, list):
            lis.extend(value)
        else:
            lis.append(value)
    else:
        pass


def _merge_value(value_a, value_b):
    merged_value = []
    _add_value_to_list(value_a, merged_value)
    _add_value_to_list(value_b, merged_value)
    return merged_value


def _recursion_merge_dict(new_dic, dic_a, dic_b):
    if not dic_a or not dic_b:
        return new_dic
    else:
        if isinstance(new_dic, dict):
            for k, v in new_dic.items():
                new_dic[k] = _recursion_merge_dict(v, dic_a.get(k, {}), dic_b.get(k, {}))
            return new_dic
        else:
            return _merge_value(dic_a, dic_b)


def merge_dicts(dic_a, dic_b):
    new_dic = deepcopy(dic_a)
    new_dic.update(dic_b)

    return _recursion_merge_dict(new_dic, dic_a, dic_b)