Mapping over values in a python dictionary

Question

Given a dictionary { k1: v1, k2: v2 ... } I want to get { k1: f(v1), k2: f(v2) ... } provided I pass a function f.

Is there an

Answer 1

Just came accross this use case. I implemented gens's answer, adding a recursive approach for handling values that are also dicts:

def mutate_dict_in_place(f, d):
    for k, v in d.iteritems():
        if isinstance(v, dict):
            mutate_dict_in_place(f, v)
        else:
            d[k] = f(v)

# Exemple handy usage
def utf8_everywhere(d):
    mutate_dict_in_place((
        lambda value:
            value.decode('utf-8')
            if isinstance(value, bytes)
            else value
        ),
        d
    )

my_dict = {'a': b'byte1', 'b': {'c': b'byte2', 'd': b'byte3'}}
utf8_everywhere(my_dict)
print(my_dict)

This can be useful when dealing with json or yaml files that encode strings as bytes in Python 2