Use of `args` and `kwargs` in Python

*args and **kwargs allows us to pass multiple arguments and keyword arguments to a function.

args

The use of * in front of a collection will unpack it. This interesting behaviour can be used to make your function accept any arbitrary number of parameters.

For example, let’s consider a function that concatenates the words passed into a complete sentence separated by space.

1. First case, where you want to support two words

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def change_words_to_sentence(word_1, word_2):
    return f'{word_1} {word_2}'

# change_words_to_sentence('Hi', 'there')
# output: 'Hi there'

1. Now let’s say you to support more than two words,

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def change_words_to_sentence(words):
    return ' '.join(words)

# change_words_to_sentence(['Hi', 'there', 'I', 'am', 'learning', 'python'])

# output: 'Hi there I am learning python'

1. One another possible way could be,

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def change_words_to_sentence(*args):
    return ' '.join(args)

# change_words_to_sentence('Hi', 'there', 'I', 'am', 'learning', 'python')

# output: 'Hi there I am learning python'

Point to note is the name *args is not important, you can use for example *words as well. It basically unpacks the arguments. Unpacking operator *

kwargs

It’s very similar to args only main difference being that it can be applied only to dictionaries.

For example,

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def change_words_to_sentence(*kwargs):
    return ' '.join(kwargs.values())

# change_words_to_sentence(a='Hi', b='there', c='!')

# output: 'Hi there !'

• Notice the use of kwargs.values(), it gives the list of values in the dictionary. Basically, any dictionary methods can be used on kwargs.
• Again, kwargs can be replaced by any other name of your choice. Main thing is the operator **.