Reference library

Dictionaries & sets

Key–value maps, uniqueness, counting, grouping, and fast lookups.

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Dictionaries & sets medium

How to Deep Merge Nested Dicts Recursively in Python

Recursively merge two Python dictionaries, with overlay values taking precedence while preserving nested structures.

dict-merge recursion nested-dicts
Python 
def deep_merge(base, overlay):
    """
    Recursively merge two dictionaries.
    Values in 'overlay' take precedence over 'base'.
    """
    result = base.copy()
    
    for key, value in overlay.items():
        if key in result and isinstance(result[key], dict) and isinstance(value, dict):
            result[key…
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