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    args and kwargs in Python

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    Python’s *args and **kwargs: Resources for Learning, Discussion, and Practicing

    We’ll discuss what the asterisk (*) and double asterisk (**) mean in Python argument syntax.We’ll also go through some examples of using args and kwargs in Python. Special symbols allow us to provide a function with an arbitrary number of arguments.

    The two exceptional

    symbols:

    args and kwargs in Python Unusual Characters This is the language of argumentation and it consists of:-

    • *args (Non-Keyword Arguments)
    • **kwargs (Keyword Arguments)

    If you’re unsure of how many arguments to pass into a function, you can use the “wildcard” or “*” notation, as shown here: *args OR **kwargs.

    function.”

    When defining a function in Python, use the *args syntax to pass an arbitrary number of arguments. It is used to convey a free-form, length-variable argument.

    list.

    • The syntax is to use the symbol * to take in a variable number of arguments; by convention, it is often used with the word args.
    • What

      *args

      allows you to do is take in more arguments than the number of formal arguments that you previously defined. With

      *args

      , any number of extra arguments can be tacked on to your current formal parameters (including zero extra arguments).
    • For example, we want to make a multiply function that takes any number of arguments and is able to multiply them all together. It can be done using *args.
    • Using the *, the variable that we associate with the * becomes an iterable meaning you can do things like iterate over it, run some higher-order functions such as map and filter, etc.

    Illustration No. 1

    A Python application demonstrating *args with an arbitrary amount of arguments

    arguments

    python3

    Final Product:


    def


    myFun(


    *


    argv):



    for


    arg


    in


    argv:



    print


    (arg)



    myFun(


    'Hello'


    ,


    'Welcome'


    ,


    'to'


    ,


    'GeeksforGeeks'


    )

    Case in point number two: 

    Hello
Welcome
to
GeeksforGeeks

    A first example Python program demonstrating *args with an

    argument

    Python3

    Resulting


    def


    myFun(arg1,


    *


    argv):



    print


    (


    "First argument :"


    , arg1)



    for


    arg


    in


    argv:



    print


    (


    "Next argument through *argv :"


    , arg)



    myFun(


    'Hello'


    ,


    'Welcome'


    ,


    'to'


    ,


    'GeeksforGeeks'


    )
     
    First argument : Hello
Next argument through *argv : Welcome
Next argument through *argv : to
Next argument through *argv : GeeksforGeeks

    It is possible to pass a keyworded, variable-length argument list to a Python function using the special syntax **kwargs in the function definition. With the double star, we refer to it as kwargs. Because of the double star, we can safely ignore keyword arguments (among other kinds of arguments).

    them).

    • A keyword argument is where you provide a name to the variable as you pass it into the function.
    • One can think of the

      kwargs

      as being a dictionary that maps each keyword to the value that we pass alongside it. That is why when we iterate over the

      kwargs

      there doesn’t seem to be any order in which they were printed out.

    Illustration 1

    An example Python program demonstrating *kwargs with a customizable set of keyword arguments. Keyworded arguments of arbitrary length passed to a function are supported by **kwargs. Specifically, “first=’Geeks'” is a case in which “first” is the key and “Geeks” is the value. In other words, value is what we place on things and people.

    key.

    Python3

    Generating


    def


    myFun(


    *


    *


    kwargs):



    for


    key, value


    in


    kwargs.items():



    print


    (


    "%s == %s"


    %


    (key, value))



    # Driver code

    myFun(first


    =


    'Geeks'


    , mid


    =


    'for'


    , last


    =


    'Geeks'


    )

    Results:

    Second Case in Point: 

    first == Geeks
mid == for
last == Geeks

    Example Python code demonstrating **kwargs for a varying number of keyword arguments. Everything else is the same, except that now we also pass a non-keyword argument that is acceptable by positional argument.(arg1 in myFun). Similarly, **kwargs will accept the keyword arguments we pass.

    right?

    Python3

    Products of the


    def


    myFun(arg1,


    *


    *


    kwargs):



    for


    key, value


    in


    kwargs.items():



    print


    (


    "%s == %s"


    %


    (key, value))



    # Driver code

    myFun(


    "Hi"


    , first


    =


    'Geeks'


    , mid


    =


    'for'


    , last


    =


    'Geeks'


    )

    Logic Gate

    first == Geeks
mid == for
last == Geeks

    First Example:

    The myFun function receives the arguments *args and **kwargs as parameters. If we call myFun with the parameters *args, we are simply passing the positional and variable-length arguments that are contained in args. Geek1 is passed to “for,” and Geek2 is passed to “Geek3,” respectively. To indicate that myFun takes keyword arguments, we use the notation **kwargs. In this case, “arg1” is the key, and “Geeks” is the value that will be passed to arg1. Similarly, “for” will be passed to arg2, and “Geeks” will be passed to arg3. We are printing all the data in after passing it all.

    lines.

    python3

    Output


    def


    myFun(arg1, arg2, arg3):



    print


    (


    "arg1:"


    , arg1)



    print


    (


    "arg2:"


    , arg2)



    print


    (


    "arg3:"


    , arg3)



    # Now we can use *args or **kwargs to

    # pass arguments to this function :

    args


    =


    (


    "Geeks"


    ,


    "for"


    ,


    "Geeks"


    )

    myFun(


    *


    args)


    kwargs


    =


    {


    "arg1"


    :


    "Geeks"


    ,


    "arg2"


    :


    "for"


    ,


    "arg3"


    :


    "Geeks"


    }

    myFun(


    *


    *


    kwargs)

    :

    Example 2: 

    arg1: Geeks
arg2: for
arg3: Geeks
arg1: Geeks
arg2: for
arg3: Geeks

    The myFun function receives the arguments *args and **kwargs as parameters. where *args are ‘geeks,’ ‘for,’ ‘geeks,’ and first=”Geeks,” mid=”for,” and last=”Geeks” are **kwargs, all of which are printed on the same line.

    python3

    Resulting


    def


    myFun(


    *


    args,


    *


    *


    kwargs):



    print


    (


    "args: "


    , args)



    print


    (


    "kwargs: "


    , kwargs)



    # Now we can use both *args ,**kwargs

    # to pass arguments to this function :

    myFun(


    'geeks'


    ,


    'for'


    ,


    'geeks'


    , first


    =


    "Geeks"


    , mid


    =


    "for"


    , last


    =


    "Geeks"


    )
     
    args: ('geeks', 'for', 'geeks')
kwargs: {'first': 'Geeks', 'mid': 'for', 'last': 'Geeks'}

    • *args receives arguments as a

      tuple

      .
    • **kwargs receives arguments as a

      dictionary.

    Python

    Input:


    class


    car():


    #defining car class



    def


    __init__(


    self


    ,


    *


    args):


    #args receives unlimited no. of arguments as an array



    self


    .speed


    =


    args[


    0


    ]


    #access args index like array does



    self


    .color


    =


    args[


    1


    ]


    #creating objects of car class


    audi


    =


    car(


    200


    ,


    'red'


    )

    bmw


    =


    car(


    250


    ,


    'black'


    )

    mb


    =


    car(


    190


    ,


    'white'


    )


    print


    (audi.color)

    print


    (bmw.speed)

    Result:

    red
250

    With

    **kwargs

    Python


    class


    car():


    #defining car class



    def


    __init__(


    self


    ,


    *


    *


    kwargs):


    #args receives unlimited no. of arguments as an array



    self


    .speed


    =


    kwargs[


    's'


    ]


    #access args index like array does



    self


    .color


    =


    kwargs[


    'c'


    ]


    #creating objects of car class


    audi


    =


    car(s


    =


    200


    ,c


    =


    'red'


    )

    bmw


    =


    car(s


    =


    250


    ,c


    =


    'black'


    )

    mb


    =


    car(s


    =


    190


    ,c


    =


    'white'


    )


    print


    (audi.color)

    print


    (bmw.speed)

    Productiveness

    red
250
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