Update dictionary keys in one line

Question

I am updating the key names of a list of dictionaries in this way:

def update_keys(vars: list) -> None:
    keys = ["A", "V", "C"]
    for v in vars:
        for key in keys:
            if key in v:
                v[key.lower()] = v.pop(key)

Is there any pythonic way to do the key loop/update in one single line? Thank you in advance!

Answer 1

You can use map with lambda to accomplish that, vars[:] will be updating the original list vars.

def update_keys(vars: list) -> None:
    keys = ["A", "V", "C"]
    vars[:] = map(lambda v: {k if k not in keys else k.lower(): v[k] for k in v}, vars)

List comprehension with the use of update can also accomplish same result.

def update_keys(vars: list) -> None:
    keys = ["A", "V", "C"]
    [v.update({key.lower(): v.pop(key) for key in keys if key in v}) for v in vars]