How to Efficiently Count Matching Key-Value Pairs in Two Dictionaries?

Comparing Dictionaries for Equivalent (Key, Value) Pairs

Question:

Given two dictionaries, how can we efficiently compare and count the number of matching key-value pairs?

Answer:

1. Iterate over Corresponding Key-Value Pairs:

As demonstrated in the original code:

<code class="python">for x_values, y_values in zip(x.iteritems(), y.iteritems()):
    if x_values == y_values:
        # They match
    else:
        # They don't match</code>

This method correctly compares key-value pairs, but its readability can be improved.

2. Use a Dictionary Comprehension:

This approach is more concise and elegant:

<code class="python">shared_items = {k: x[k] for k in x if k in y and x[k] == y[k]}</code>

This creates a new dictionary named shared_items that contains only the key-value pairs that are present in both x and y with the same values.

3. Count Matching Pairs:

To count the number of matching pairs, we can use the len() function:

<code class="python">print(len(shared_items))</code>

This will output the number of key-value pairs that are equal in both dictionaries.

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