How to replace keys (key labels) in a dictionary from a list of tokens

Question

I have a dictionary

dict = {'a': 'cat', 'b':'dog'}

and I want to replace the keys in the dict with new keys (or key labels) from a list ['c', 'd'] so that I get (the same)

dict = {'c': 'cat', 'd':'dog'} . How can I do this?

Answer 1

You can define the relation between the old keys and their replacements, in another dictionary, like this. Here, mapping is the dictionary which maps the old keys with the new keys.

d, mapping = {'a': 'cat', 'b':'dog'}, {"a":"c", "b":"d"}
print {mapping[k]:v for k, v in d.items()}

Output

{'c': 'cat', 'd': 'dog'}

Answer 2

As already has been pointed out, a dictionary is not ordered. So if you want to replace your keys with values from a list (which is ordered), you will need to specify how the keys of your dict are ordered. Something along these lines:

def replaceKeys (d, newKeys, sort):
    return {newKeys[idx]: v for idx, (_, v)
        in enumerate(sorted(d.items(), key = lambda kv: sort(kv[0])))}

d = {'cat': 'gato', 'dog': 'chucho', 'mule': 'mula'}
d2 = replaceKeys(d, ['a', 'b', 'c'], lambda oldKey: oldKey) #sort alphabetically
print(d2)
d2 = replaceKeys(d, ['a', 'b', 'c'], lambda oldKey: -len(oldKey)) #sort by length ascending
print(d2)
d2 = replaceKeys(d, ['a', 'b', 'c'], lambda oldKey: oldKey[2]) #sort by third letter
print(d2)