my_dict_1 = {'a' : 1, 'b' : 1}
my_dict_2 = {'a' : 2, 'b' : 2, 'c' : 2}

my_dict_1.update(my_dict_2, ['a', 'c'])

should result for my_dict_1:

{'a' : 2, 'b' : 1, 'c' : 2}

Please post to python-ideas first, and note a moratorium on builtin changes is inplace.

FWIW, the usual way to spell this in Python is:

 my_dict_1.update((k, my_dict_2[k]) for k in ['a', 'c'])

We try to keep filtering operations separate from map/fold operations for orthognality.