Update value in nested dictionary-CodePudding

I have a dictionary like this. Length may vary:

dct: dict = {'first': {'val1': {'subval1': 1, 'subval2': 555}, 'val2': 2, 'val3': 3}, 'second': {'val1': 1, 'val2': 2, 'val3': 3}}

I have a "path" to a value and a new content for that value:

path = ['first', 'val1', 'subval1', 1000]

How can I change the value in the dictionary? The "path" can change, the values in it too. It could be:

path = ['third', 'firstval', 'val3', 'subval2', 999]

or something else.

CodePudding user response：

You can write a recursive function to create dictionaries from your paths and then update your initial dictionary:

my_dict = {'first': {'val1': {'subval1': 1, 'subval2': 555}, 'val2': 2, 'val3': 3}, 'second': {'val1': 1, 'val2': 2, 'val3': 3}}

update_path = ['first', 'val1', 'subval1', 1000]

def create_dict_from_path(l):
    if len(l) > 1:
        return {l[0]: create_dict_from_path(l[1:])}
    else:
        return l[0]

update_dict = create_dict_from_path(update_path)
my_dict.update(update_dict)

print(my_dict)

Output:

{'first': {'val1': {'subval1': 1000}}, 'second': {'val1': 1, 'val2': 2, 'val3': 3}}

Edit: if you want to go until the deepest level of your dictionary in order to keep all key/value pairs, the recursive function will be a bit more intricated:

def update_dict_from_path(d, l):
    if len(l) > 2 and l[0] in d:
        update_dict_from_path(d[l[0]], l[1:])
    elif len(l) == 2 and l[0] in d:
        d[l[0]] =  l[1]

update_dict_from_path(my_dict, update_path)
print(my_dict)

Output:

{'first': {'val1': {'subval1': 1000, 'subval2': 555}, 'val2': 2, 'val3': 3}, 'second': {'val1': 1, 'val2': 2, 'val3': 3}}

Edit2: you might wanna check if you're not overwriting nested dictionaries with scalar values in case the same key is found at different levels: elif len(l) == 2 and l[0] in d and not isinstance(d[l[0]], dict):