Python - Extract Keys with specific Value Type

Python - Extract Keys with specific Value Type

In this tutorial, we'll extract keys from a dictionary that have values of a specific data type. This can be useful in scenarios where dictionaries might have mixed value types, and you want to filter them based on a certain type.

Task:

Given a dictionary data_dict, extract keys whose values are of a specific type T.

Approach:

  1. Iterate through each key-value pair in the dictionary.
  2. Check the type of the value.
  3. If the type matches T, store the key.

Code:

def extract_keys_with_type(data_dict, T): """ Extract keys from data_dict whose values are of type T. """ # Use a list comprehension to extract the keys matching_keys = [key for key, value in data_dict.items() if isinstance(value, T)] return matching_keys # Example data_dict = { "name": "Alice", "age": 25, "is_student": False, "grades": [85, 90, 88], "address": {"city": "New York", "zipcode": 10001}, "average_grade": 87.67 } # Extract keys with string values print(extract_keys_with_type(data_dict, str)) # Output: ['name'] # Extract keys with list values print(extract_keys_with_type(data_dict, list)) # Output: ['grades'] # Extract keys with dictionary values print(extract_keys_with_type(data_dict, dict)) # Output: ['address']

In the example above:

  • The key "name" has a string value "Alice".
  • The key "grades" has a list value [85, 90, 88].
  • The key "address" has a dictionary value {"city": "New York", "zipcode": 10001}.

The function extract_keys_with_type returns the keys based on the specified type.

Note: This function uses the isinstance function, which checks if an object is an instance of a specified type or class, making it a flexible and reliable way to determine types in Python.

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