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Asked: 2024-09-22T09:37:25+05:30 In:

How can I retrieve a specific selection of key-value pairs from a dictionary in Python? I want to filter the dictionary based on a list of desired keys, keeping only the entries that match. What would be an efficient way to accomplish this task?

Hey everyone! I’m working on a project in Python and I’ve hit a bit of a snag with dictionaries.

Basically, I have a dictionary that contains a lot of information, but I only need to extract certain key-value pairs based on a predefined list of keys. I was wondering, what’s the most efficient way to filter the dictionary so that I only keep the entries that match my list of desired keys?

For example, if my dictionary looks like this:

“`python
data = {
‘name’: ‘Alice’,
‘age’: 30,
‘city’: ‘Wonderland’,
‘occupation’: ‘Engineer’
}
“`

And I have a list of keys:

“`python
desired_keys = [‘name’, ‘occupation’]
“`

How can I retrieve just the key-value pairs for ‘name’ and ‘occupation’?

Any tips or code snippets would be super helpful! Thanks!

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    2 Answers

    1. “`html





      Filtering Dictionary in Python

      Filtering Dictionary Based on Key List

      To filter a dictionary based on a list of desired keys, you can use a dictionary comprehension. Here’s how you can do it:

      
data = {
    'name': 'Alice',
    'age': 30,
    'city': 'Wonderland',
    'occupation': 'Engineer'
}

desired_keys = ['name', 'occupation']

filtered_data = {key: data[key] for key in desired_keys if key in data}
print(filtered_data)

      This code will create a new dictionary, filtered_data, that only contains the key-value pairs for the keys specified in desired_keys. The output will be:

      
{'name': 'Alice', 'occupation': 'Engineer'}

      Feel free to ask more questions if you need further assistance!



      “`


    2. To efficiently filter your dictionary based on a predefined list of keys, you can utilize a dictionary comprehension. This allows you to create a new dictionary that only includes the entries from your original dictionary that match the keys in your list. Here’s a simple code snippet to accomplish this:

      filtered_data = {key: data[key] for key in desired_keys if key in data}

      In your case, using the provided dictionary data and list desired_keys, this will generate a new dictionary filtered_data containing only the desired key-value pairs, resulting in:

      {'name': 'Alice', 'occupation': 'Engineer'}

      This method is not only concise but also efficient, as it leverages the fast membership test in dictionaries to ensure you’re only accessing keys that actually exist in your original dictionary.


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