Rename a dictionary key

For a regular dict, you can use:

mydict[k_new] = mydict.pop(k_old)

This will move the item to the end of the dict, unless k_new was already existing in which case it will overwrite the value in-place.

For a Python 3.7+ dict where you additionally want to preserve the ordering, the simplest is to rebuild an entirely new instance. For example, renaming key 2 to 'two':

>>> d = {0:0, 1:1, 2:2, 3:3}>>> {"two" if k == 2 else k:v for k,v in d.items()}{0: 0, 1: 1, 'two': 2, 3: 3}

The same is true for an OrderedDict, where you can't use dict comprehension syntax, but you can use a generator expression:

OrderedDict((k_new if k == k_old else k, v) for k, v in od.items())

Modifying the key itself, as the question asks for, is impractical because keys are hashable which usually implies they're immutable and can't be modified.

Using a check for newkey!=oldkey, this way you can do:

if newkey!=oldkey:      dictionary[newkey] = dictionary[oldkey]    del dictionary[oldkey]

In case of renaming all dictionary keys:

target_dict = {'k1':'v1', 'k2':'v2', 'k3':'v3'}new_keys = ['k4','k5','k6']for key,n_key in zip(target_dict.keys(), new_keys):    target_dict[n_key] = target_dict.pop(key)