PYTHON
Merge Multiple Dictionaries with Various Strategies
Explore different Python techniques for merging dictionaries, including unpacking operators and dict.update(), to combine data efficiently from multiple sources in modern Python.
dict1 = {'a': 1, 'b': 2}
dict2 = {'c': 3, 'd': 4}
dict3 = {'a': 5, 'e': 6}
# Strategy 1: Using the dictionary union operator (Python 3.9+)
merged_dict_union = dict1 | dict2 | dict3
print(f"Merged (union operator): {merged_dict_union}")
# Output: {'a': 5, 'b': 2, 'c': 3, 'd': 4, 'e': 6} (dict3's 'a' overwrites dict1's 'a')
# Strategy 2: Using dictionary unpacking (earlier Python versions & common)
merged_dict_unpack = {**dict1, **dict2, **dict3}
print(f"Merged (unpacking): {merged_dict_unpack}")
# Output: {'a': 5, 'b': 2, 'c': 3, 'd': 4, 'e': 6} (dict3's 'a' overwrites dict1's 'a')
# Strategy 3: Using dict.update() (modifies in-place)
combined_dict_update = dict1.copy() # Create a copy to avoid modifying original dict1
combined_dict_update.update(dict2)
combined_dict_update.update(dict3)
print(f"Merged (update method): {combined_dict_update}")
# Output: {'a': 5, 'b': 2, 'c': 3, 'd': 4, 'e': 6} (dict3's 'a' overwrites dict1's 'a')
How it works: This snippet demonstrates three common strategies for merging multiple dictionaries in Python. The dictionary union operator (`|`), introduced in Python 3.9, provides a concise way to merge dictionaries, with later dictionaries overriding values for duplicate keys. Dictionary unpacking (`**`) offers a similar non-mutating approach for older Python versions. The `dict.update()` method merges dictionaries in-place, modifying the target dictionary. All methods handle duplicate keys by using the value from the dictionary that appears later in the merge operation.