The Multidict, is a dictionary-like structure, having key-value pairs, but the ‘same key’ can occur multiple times, in the collection. The features of a Multidict in Python are as follows:

• The insertion order of the collection is maintained. 
• Multiple values in the collection can have the same key. 
• The keys are stored as a ‘string’.

Installation

pip install multidict

Creating a multidict in Python

Here, we are creating a multidict with the key ‘b‘ having multiple values, 2 and 3, and ‘c’ with 5 and 7.

Output:

<MultiDict(‘a’: 1, ‘b’: 2, ‘b’: 3, ‘c’: 5, ‘d’: 4, ‘c’: 7)>

Extract multidict values to a list in Python

Here, we are Creating an empty list, and then using a Python for loop we append only the values of a multidict.

Output:

List of values of multidict: [1, 2, 3, 5, 4, 7]

Extract multidict keys to a list in Python

Here, we are Creating an empty list, and then using a Python for loop we append only the key of a multidict.

Output:

List of keys of multidict: [‘a’, ‘b’, ‘b’, ‘c’, ‘d’, ‘c’]

Extract specific values from a multidict to a list

Example 1: Using getall()

This method returns the values associated with a particular key of Multidict. We need to pass the key whose values are desired as a parameter to the method. The method returns a list of values for the key. It will throw a ‘KeyError’ if the specified key is not found.

Output:

Key B values: [2, 3]
Key C values: [5, 7]

Example 2: Using popall()

This method returns the values associated with a particular key of Multidict. If the key specified, is in a Multidict structure then it removes all occurrences of the key and returns a list of values of the key. It throws a ‘KeyError’ if the specified key is not found.

Output:

Pop out values of key C: [5, 7]

Multidict after popping key C: <MultiDict(‘a’: 1, ‘b’: 2, ‘b’: 3, ‘d’: 4)>