How to Combine Multiple Dictionaries into a Single Entity in Python?

Merging Multiple Dictionaries into a Single Entity

When dealing with multiple dictionaries, there often arises a need to consolidate them into a single, comprehensive one. This scenario can be encountered in various programming contexts. Let's explore how to merge a list of dictionaries into a single dictionary while handling the potential issue of duplicate keys.

Approach: Iterative Update

To merge a list of dictionaries, you can utilize a straightforward iterative approach. This involves looping through each dictionary in the list and updating an accumulating result dictionary with its contents. Using this method, if multiple dictionaries contain the same key, the value from the latter dictionary will overwrite the existing value in the result dictionary.

result = {}
for d in L:
    result.update(d)

Example:

Given a list of dictionaries:

L = [{'a':1}, {'b':2}, {'c':1}, {'d':2}]

Applying the iterative update approach:

result = {}
for d in L:
    result.update(d)

The resulting dictionary will be:

{'a':1,'c':1,'b':2,'d':2}

Comprehension-Based Approach (Python 2.7 and above)

As an alternative, you can leverage comprehensions to perform the merge operation concisely:

result = {k: v for d in L for k, v in d.items()}

Note:

Keep in mind that dictionaries cannot have duplicate keys. As a result, when merging multiple dictionaries, any duplicate keys will be overwritten by the last corresponding value encountered. If you require the merging of multiple values associated with matching keys, refer to related resources that address this specific scenario.

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