Use a dict comprehension with
zip
:
>>> {k:[x-y for x, y in zip(d1[k], d2[k])] for k in d1}
{'a': [9, 10, 11], 'c': [7, 7, 8], 'b': [7, 7, 9], 'd': [3, 5, 5]}
or map
:
>>> from operator import sub
>>> {k:map(sub, d1[k], d2[k]) for k in d1}
{'a': [9, 10, 11], 'c': [7, 7, 8], 'b': [7, 7, 9], 'd': [3, 5, 5]}