If you want a merged copy that does not alter the original dicts and watches for name conflicts, you might want to try this solution:
#! /usr/bin/env python3
import copy
import itertools
def main():
dict_a = dict(a=[1], b=[2])
dict_b = dict(b=[3], c=[4])
complete_merge = merge_dicts(dict_a, dict_b, True)
print(complete_merge)
resolved_merge = merge_dicts(dict_a, dict_b, False)
print(resolved_merge)
def merge_dicts(a, b, complete):
new_dict = copy.deepcopy(a)
if complete:
for key, value in b.items():
new_dict.setdefault(key, []).extend(value)
else:
for key, value in b.items():
if key in new_dict:
# rename first key
counter = itertools.count(1)
while True:
new_key = f'{key}_{next(counter)}'
if new_key not in new_dict:
new_dict[new_key] = new_dict.pop(key)
break
# create second key
while True:
new_key = f'{key}_{next(counter)}'
if new_key not in new_dict:
new_dict[new_key] = value
break
else:
new_dict[key] = value
return new_dict
if __name__ == '__main__':
main()
The program displays the following representation for the two merged dictionaries:
{'a': [1], 'b': [2, 3], 'c': [4]}
{'a': [1], 'b_1': [2], 'b_2': [3], 'c': [4]}