Python Dictionary Merging with Overlapping Keys - advanced patterns in Python 3.9
I'm collaborating on a project where I'm trying to merge two dictionaries in Python 3.9 where both dictionaries contain some overlapping keys. I expected the values of the overlapping keys to be combined into a list, but instead, I'm getting just one of the values, which is not what I want. Here's the code I'm using: ```python from collections import defaultdict dict1 = {'a': 1, 'b': 2} dict2 = {'b': 3, 'c': 4} merged_dict = defaultdict(list) for d in (dict1, dict2): for key, value in d.items(): merged_dict[key].append(value) print(dict(merged_dict)) # Expected: {'a': [1], 'b': [2, 3], 'c': [4]} ``` Instead, I see the output as `{'a': [1], 'b': [3], 'c': [4]}`. Iām not sure why 'b' only contains the value `3`. I've tried changing the merge logic, but nothing seems to work. Can someone guide to understand why this is happening? Am I missing something in the way I'm merging the dictionaries? This is crucial for my project where I need to keep track of all values associated with the same keys. This is part of a larger mobile app I'm building. Any ideas how to fix this?