Flexible Dictionary Merging: Implementing Custom Conflict Resolvers

Last update on April 10 2025 12:54:11 (UTC/GMT +8 hours)

86. Dictionary Merging with Custom Conflict Resolution

Write a Python function that merges multiple dictionaries with a custom conflict resolution strategy. The function should take any number of dictionaries and a conflict resolution function. The conflict resolution function should take the key and all conflicting values and return the resolved value.

Solution:

Python Code:

# Define a function to merge multiple dictionaries with a custom conflict resolution strategy.
def merge_dicts_with_resolver(resolver_func, *dicts):
    """
    Merges multiple dictionaries with a custom conflict resolution strategy.
    
    Args:
        resolver_func: Function that takes a key and list of conflicting values
                      and returns the resolved value
        *dicts: Dictionaries to merge
    
    Returns:
        A new merged dictionary
    """
    # If no dictionaries are provided, return an empty dictionary.
    if not dicts:
        return {}
    
    # Initialize a set to collect all unique keys from the input dictionaries.
    all_keys = set()
    for d in dicts:
        # Add all keys from each dictionary to the set of unique keys.
        all_keys.update(d.keys())
    
    # Initialize an empty dictionary to store the merged result.
    result = {}
    for key in all_keys:
        # Collect all values associated with the current key across all dictionaries.
        values = [d[key] for d in dicts if key in d]
        
        # If there's only one value for the key, no conflict exists; assign it directly.
        if len(values) == 1:
            result[key] = values[0]
        else:
            # Use the resolver function to resolve conflicts when multiple values exist.
            result[key] = resolver_func(key, values)
    
    # Return the final merged dictionary after resolving all conflicts.
    return result

# Example dictionaries to merge
# Define three dictionaries with overlapping keys to demonstrate merging behavior.
dict1 = {'a': 1, 'b': 2, 'c': 3}
dict2 = {'b': 20, 'd': 4, 'e': 5}
dict3 = {'a': 10, 'c': 30, 'e': 50}

# Example resolver functions
# Define a resolver function that resolves conflicts by taking the maximum value.
def max_resolver(key, values):
    return max(values)

# Define a resolver function that resolves conflicts by summing all conflicting values.
def sum_resolver(key, values):
    return sum(values)

# Define a resolver function that resolves conflicts by calculating the average of conflicting values.
def avg_resolver(key, values):
    return sum(values) / len(values)

# Merge dictionaries using different resolver functions
# Merge dictionaries using the maximum value resolver.
max_result = merge_dicts_with_resolver(max_resolver, dict1, dict2, dict3)

# Merge dictionaries using the sum resolver.
sum_result = merge_dicts_with_resolver(sum_resolver, dict1, dict2, dict3)

# Merge dictionaries using the average resolver.
avg_result = merge_dicts_with_resolver(avg_resolver, dict1, dict2, dict3)

# Print the results of merging with different resolvers.
print(f"Max resolver: {max_result}")
print(f"Sum resolver: {sum_result}")
print(f"Average resolver: {avg_result}")

Output:

Max resolver: {'c': 30, 'a': 10, 'b': 20, 'e': 50, 'd': 4}
Sum resolver: {'c': 33, 'a': 11, 'b': 22, 'e': 55, 'd': 4}
Average resolver: {'c': 16.5, 'a': 5.5, 'b': 11.0, 'e': 27.5, 'd': 4}

Explanation of Each Line:

Function Definition : Defines merge_dicts_with_resolver, a function to merge multiple dictionaries with a custom conflict resolution strategy.
Docstring : Provides a description of the function, its arguments, and its return value.
Empty Input Check : Checks if no dictionaries are provided and returns an empty dictionary if true.
Unique Keys Collection : Initializes a set to collect all unique keys from the input dictionaries.
Update Unique Keys : Iterates through each dictionary and adds its keys to the set of unique keys.
Initialize Result Dictionary : Creates an empty dictionary to store the merged result.
Iterate Over Keys : Loops through each unique key to process its values across dictionaries.
Collect Values : Gathers all values associated with the current key from the input dictionaries.
Single Value Check : If only one value exists for the key, assigns it directly to the result.
Conflict Resolution : Uses the provided resolver function to resolve conflicts when multiple values exist for the key.
Return Merged Dictionary : Returns the final merged dictionary after processing all keys.
Example Dictionaries : Defines three dictionaries with overlapping keys to demonstrate merging behavior.
Maximum Resolver : Defines a resolver function that resolves conflicts by taking the maximum value.
Sum Resolver : Defines a resolver function that resolves conflicts by summing all conflicting values.
Average Resolver : Defines a resolver function that resolves conflicts by calculating the average of conflicting values.
Merge with Max Resolver : Merges dictionaries using the maximum value resolver.
Merge with Sum Resolver : Merges dictionaries using the sum resolver.
Merge with Average Resolver : Merges dictionaries using the average resolver.
Print Results : Prints the results of merging dictionaries with different resolvers to verify the output.

Explanation – Python Dictionary Merging with Custom Conflict Resolution

Concept: Merge multiple dictionaries with custom logic for resolving key conflicts.
Challenge: Design a flexible system where conflict resolution logic is provided as a function parameter.
Key Skills:

Higher-order functions
Flexible API design
Advanced dictionary operations

Applications:

Configuration management with layered settings
Data integration from multiple sources
Implementing fallback systems
Reconciling conflicting data sets

Benefits:

Provides sophisticated control over merging behavior
Allows context-specific conflict resolution
Extends Python's dictionary capabilities beyond standard library functions

For more Practice: Solve these Related Problems:

Write a Python function to merge dictionaries by applying different merging strategies based on key patterns.
Write a Python function to resolve dictionary merge conflicts using machine learning models trained on past merge decisions.
Write a Python function to merge dictionaries and store conflict metadata for later manual review.
Write a Python function that allows users to define conflict resolution strategies dynamically via configuration files.

Python Code Editor:

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