How to Safely Merge Two Dictionaries in Python 3.9 Without Overwriting Keys?
I've been struggling with this for a few days now and could really use some help... I'm getting frustrated with I'm building a feature where I'm trying to merge two dictionaries in Python 3.9 where I want to combine values of the same keys into lists instead of overwriting them. For example, if I have two dictionaries like this: ```python dict_a = {'key1': 'value1', 'key2': 'value2'} dict_b = {'key1': 'value3', 'key2': 'value4', 'key3': 'value5'} ``` I want the merged result to look like this: ```python merged_dict = {'key1': ['value1', 'value3'], 'key2': ['value2', 'value4'], 'key3': ['value5']} ``` I've tried using a simple loop, but I end up overwriting the values: ```python for key, value in dict_b.items(): dict_a[key] = value ``` This gives me `{'key1': 'value3', 'key2': 'value4', 'key3': 'value5'}`, which is not what I want. I also attempted using `collections.defaultdict`, but I'm not sure how to integrate it properly with existing keys. Can someone suggest a way to achieve this safely? Additionally, I'm curious if there are any performance implications of merging large dictionaries this way, especially if I need to do it frequently in my application. Any insights or alternative approaches would be greatly appreciated! I'm working in a macOS environment. Is this even possible? What's the correct way to implement this? This is my first time working with Python 3.10. Any examples would be super helpful.