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Python

Call a function with a random number of arguments

I have a function like that:

def my_function(*args):
    for arg in args:
        print(arg)

and I would like to call it with a random number of arguments. Something like:

args = tuple(random.randint(1, 500) for _ in range(10))
my_function(args)

And I can't make it work. Any suggestions?

Thanks

Jacques

2 Answers

Chris Freeman
MOD
Chris Freeman
Treehouse Moderator 67,989 Points

Jacques Plomion, you are correct that my_function is seeing the tuple as a single argument. The power of the asterisk in *args can be used in two ways:

  • as a catchall to receive an arbitrary number of arguments, and
  • to expand a container into individual arguments

The second way is used when you see code like:

    def __init__(*args, **kwargs):  # used here to catch all arguments
        super().__init(*args, **kwargs)  # used here to expand back to individual arguments

So, the simple solution is to call your function as: my_function(*args)

>>> import random
>>> args = tuple(random.randint(1, 500) for _ in range(10))
>>> args
(284, 481, 276, 323, 22, 1, 274, 395, 425, 381)
>>> my_function(args)
(284, 481, 276, 323, 22, 1, 274, 395, 425, 381)
>>> my_function(*args)
284
481
276
323
22
1
274
395
425
381

Post back if you have more questions. Good Luck!!

Thanks Chris.

Clayton Perszyk
MOD
Clayton Perszyk
Treehouse Moderator 48,107 Points

Hey Jacques,

You need to import the random library:

import random

then you can call:

random.randint(n1, n2)

or

from random import randint

then you can call:

randint(n1, n2)

Hi Clayton,

Thanks for taking the time to respond to me. I guess I didn't explain what I am trying to do well enough so let me try again:

I am trying to call my_function with a random number of arguments in *args. The args would be determined randomly when I run the script. So doing:

args = tuple(random.randint(1, 500) for _ in range(10))
my_function(args)

creates a tuple with a random number of arguments and when I call my_function I get this result:

(332, 224, 406, 410, 352, 306, 245, 455, 456, 89)   # for example

I think this is because my tuple is seen as one argument (a tuple) when I would like it to be seen as several integer arguments. I hope it is more clear. And again, thank you for helping with this.

Jacques