How to change values in a nested dictionary

Question

I need to change values in a nested dictionary. Consider this dictionary:

stocks = {
        'name': 'stocks',
        'IBM': 146.48,
        'MSFT': 44.11,
        'CSCO': 25.54,
        'micro': {'name': 'micro', 'age': 1}
    }

I need to loop through all the keys and change the values of all the name keys.

stocks.name
stocks.micro.name

These keys need to be changed. But, I will not know which keys to change before hand. So, I'll need to loop through keys and change the values.

Example

change_keys("name", "test")

Output

{
     'name': 'test',
     'IBM': 146.48,
     'MSFT': 44.11,
     'CSCO': 25.54,
     'micro': {'name': 'test', 'age': 1}
}

"But, I will not know which keys to change before hand" Didn't you say you need to change all the "name" keys? — DeepSpace
– DeepSpace, Commented May 14, 2018 at 19:01
@DeepSpace yes thats right. That is just an example because there are multiple keys named 'name'. How would I ensure the correct value is changed? — Luke101
– Luke101, Commented May 14, 2018 at 19:03
Can you add an example of what input/output you expect? It's not clear how you want this dict mutated. — TemporalWolf
– TemporalWolf, Commented May 14, 2018 at 19:05

DeepSpace · Accepted Answer · 2018-05-14 19:21:16Z

4

A recursive solution that supports unknown number of nesting levels:

def change_key(d, required_key, new_value):
    for k, v in d.items():
        if isinstance(v, dict):
            change_key(v, required_key, new_value)
        if k == required_key:
            d[k] = new_value

stocks = {
    'name': 'stocks',
    'IBM': 146.48,
    'MSFT': 44.11,
    'CSCO': 25.54,
    'micro': {'name': 'micro', 'age': 1}
}


change_key(stocks, 'name', 'new_value')
print(stocks)
#  {'name': 'new_value', 
#  'MSFT': 44.11, 
#  'CSCO': 25.54,
#  'IBM': 146.48,
#  'micro': {'name': 'new_value', 
#            'age': 1}
#  }

edited May 14, 2018 at 19:21

answered May 14, 2018 at 19:03

DeepSpace

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Comments

Attersson · Accepted Answer · 2018-05-14 19:12:25Z

2

def changeKeys(d, repl):
    for k,v in zip(d.keys(),d.values()):
        if isinstance(v, dict):
            changeKeys(v,repl)
        elif k == "name":
            d[k]= repl

edited May 14, 2018 at 19:12

answered May 14, 2018 at 19:05

Attersson

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6 Comments

MegaIng Over a year ago

zip(d.keys(),d.values())? WTF? d.items()!

Attersson Over a year ago

I change where the key is 'name' into the value he wants, right?

DeepSpace Over a year ago

@Attersson Not really

TemporalWolf Over a year ago

v= repl should be d[k] = repl, otherwise you're changing v which is just the value of value, rather than what is stored in the dict (when the item is immutable, like a string)

Luke101 Over a year ago

Dont change the keys. I just want the values changed. As illustrated in the sample output in the question.

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