How do I extract a list of unique dictionaries from a list of potentially duplicate dictionaries?

How to Get a List of Unique Dictionaries

Given a list of dictionaries, obtaining a list of unique dictionaries can be useful for various purposes. The challenge lies in removing duplicate dictionaries while preserving the content.

Solution

One efficient approach involves creating a temporary dictionary where the key is the unique identifier from each dictionary. This effectively filters out any duplicates. The values of this temporary dictionary can then be retrieved as a list of unique dictionaries.

<code class="python"># In Python 3
unique_dicts = list({v['id']:v for v in L}.values())

# In Python 2.7
unique_dicts = {v['id']:v for v in L}.values()</code>

Example

Consider the list of dictionaries:

<code class="python">L = [
    {'id': 1, 'name': 'john', 'age': 34},
    {'id': 1, 'name': 'john', 'age': 34},
    {'id': 2, 'name': 'hanna', 'age': 30},
]</code>

After applying the solution:

<code class="python">print(unique_dicts)
[{'id': 1, 'name': 'john', 'age': 34}, {'id': 2, 'name': 'hanna', 'age': 30}]</code>

Key Insight

The key insight is that dictionaries can be converted into unique representations by using a common identifier as the key. This allows for efficient filtering of duplicates while preserving the original dictionary content.

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