Functions that Accept Variable Length Key Value Pair as Arguments

To pass a variable-length key-value pair as an argument to a function, Python provides a feature called **kwargs.
kwargs stands for Keyword arguments. It proves to be an efficient solution when one wants to deal with named arguments (arguments passed with a specific name (key) along with their value) in their function.

Here's an example:

def func(**kwargs): for key, val in kwargs.items(): print(key, ": ", val) func(name="GFG", country="India") 

name : GFG country : India 

Syntax:

def functionName(**kwargs):
# code
kwargs: it's the variable name using which we can access the arguments keys and values.

Note: adding '**' to any term makes it a kwargs parameter. It accepts keywords as arguments. 

Let's discuss some use cases of **kwargs with examples to get a better understanding.

Passing and Printing Key-Value Pairs

In this example, we define a function that accepts keyword arguments and prints them as a dictionary.

def func(**kwargs): print(kwargs) func(k1 = "Geeks", k2 = "For", k3 = "Geeks") 

{'k1': 'Geeks', 'k2': 'For', 'k3': 'Geeks'} 

Iterating Through Keyword Arguments

We can loop through kwargs using kwargs.items() to access both the keys and values.

def func(**kwargs): for key, val in kwargs.items(): print("The value of ", key," is", val) func(short_form = "GFG", full_name="geeksforgeeks") 

The value of short_form is GFG The value of full_name is geeksforgeeks 

Concatenating String Arguments

This example shows how **kwargs can be used to concatenate multiple string values passed as keyword arguments.

def func(**kwargs): # initialising empty string s = "" for ele in kwargs.values(): s += ele return s print(func(a="g", b="F", c="g")) 

gFg 

Multiplying Numeric Values

We can easily perform arithmetic operations over the items of argumets.

def func(**kwargs): ans = 1 for ele in kwargs.values(): ans *= ele return ans print(func(a=1, b=2, c=3, d=4, e=5)) 

120 

Merging Two Dictionaries

We can create a function that accepts two dictionaries as keyword arguments and merges them into one.

def func(**kwargs): res = {} for key, val in kwargs.items(): res[key] = val return res print(func(first={"a": 1, "b": 2}, second={"c": 3, "d": 4})) 

{'first': {'a': 1, 'b': 2}, 'second': {'c': 3, 'd': 4}} 

Formatting a String with Dynamic Values

Using **kwargs, we can accept multiple key-value pairs and dynamically format them into a structured string. This is particularly useful when dealing with flexible data inputs, such as logging messages, creating query strings, or displaying structured information.

def func(**kwargs): return " ".join([f"{key}={val}" for key, val in kwargs.items()]) print(func(name="GfG",country="India")) 

name=GfG country=India 

Explanation:

• accessing key-value data using for key, value in kwargs.items().
• " ".join(formatted_pairs) combines the formatted key-value pairs into a single string, separated by spaces.