Mapping of Keys using dictionary and lists in Python

December 30, 2021

I have a list of list of dictionary like below:

ini_dict = [[{'nikhil': 1, 'vashu': 5,
              'manjeet': 10, 'akshat': 16}, {'nikhil': 1, 'vashu': 5,
                                             'manjeet': 10, 'akshat': 15}]]

I have modified and reduced one level like below:

mod = []
for i in ini_dict:
    for j in i:
        mod.append({item: values for item, values in j.items()})

This gives me output as below:

[{'nikhil': 1, 'vashu': 5, 'manjeet': 10, 'akshat': 15}, {'nikhil': 1, 'vashu': 5, 'manjeet': 10, 'akshat': 15}]

Now, I have another set of Keys dictionary using which the keys of the above data should be replaced by it.

result_dict1 = {"nikhil": "Nikhil", "vashu": "Vashu", "manjeet": "Manjeet", "akshat": "Akshat"}

Now, I have tried the below code but it’s not giving me the output I need:

final = []
for j, k in result_dict1.items():
    for i in mod:
        for x, y in i.items():
            final += [{k: y}]

Output:

[{'Nikhil': 1}, {'Nikhil': 5}, {'Nikhil': 10}, {'Nikhil': 15}, {'Nikhil': 1}, {'Nikhil': 5}, {'Nikhil': 10}, {'Nikhil': 15}, {'Vashu': 1}, {'Vashu': 5}, {'Vashu': 10}, {'Vashu': 15}, {'Vashu': 1}, {'Vashu': 5}, {'Vashu': 10}, {'Vashu': 15}, {'Manjeet': 1}, {'Manjeet': 5}, {'Manjeet': 10}, {'Manjeet': 15}, {'Manjeet': 1}, {'Manjeet': 5}, {'Manjeet': 10}, {'Manjeet': 15}, {'Akshat': 1}, {'Akshat': 5}, {'Akshat': 10}, {'Akshat': 15}, {'Akshat': 1}, {'Akshat': 5}, {'Akshat': 10}, {'Akshat': 15}]

Keys are replaced but the combination is 1:N.

Expected output:

[{'Nikhil': 1, 'Vashu': 5, 'Manjeet': 10, 'Akshat': 15}, {'Nikhil': 1, 'Vashu': 5, 'Manjeet': 10, 'Akshat': 15}]

>Solution :

You don’t seem to check if a key of the inner dictionary in mod matches the key in the replacement dict, that’s an issue.

A list comprehension with a dict comprehension does the result:

>>> [{result_dict1[key]: value for key, value in inner_dict.items()}
     for inner_dict in mod]

[{'Nikhil': 1, 'Vashu': 5, 'Manjeet': 10, 'Akshat': 15},
 {'Nikhil': 1, 'Vashu': 5, 'Manjeet': 10, 'Akshat': 15}]

So the dict comprehension is changing the inner dicitionaries of the mod such that the keys are replaced from result_dict1. The list comprehension helps do this for every inner dictionary.

This will err if result_dict1 isn’t comprehensive enough.