Generalizing my python function

Question

I am trying to make my function be able to accept as many inputs or as little inputs as needed.

Currently I have 3 inputs that are hard coded (loc1, loc2, loc3). Is there a way to keep the inputs variable so if I just had 1 input, or if I have 5 inputs, my function can be flexible?

def np_array(loc1, loc2, loc3):
    loc_a = np.array(loc1)
    loc_b = np.array(loc2)
    loc_c = np.array(loc3)

    pressure_vector1 = np.subtract(loc_a, loc_c)
    pressure_vector2 = np.subtract(loc_a, loc_b)

    movement_vector = np.add(pressure_vector1, pressure_vector2)

    return movement_vector

you could also simply pass a list as the argument, which you fill with your args. — Zinki, Aug 13 '18 at 13:29
you need variable arguments. ref. https://stackoverflow.com/questions/919680/can-a-variable-number-of-arguments-be-passed-to-a-function — Junhee Shin, Aug 13 '18 at 13:31

score 2 · Answer 1 · answered Aug 13 '18 at 13:38

You can use *args or **kwargs for this.

In Python, the single-asterisk form of *args can be used as a parameter to send a non-keyworded variable-length argument list to functions. It is worth noting that the asterisk (*) is the important element here, as the word args is the established conventional idiom, though it is not enforced by the language.

The double asterisk form of **kwargs is used to pass a keyworded, variable-length argument dictionary to a function. Again, the two asterisks (**) are the important element here, as the word kwargs is conventionally used, though not enforced by the language.

Like *args, **kwargs can take however many arguments you would like to supply to it. However, **kwargs differs from *args in that you will need to assign keywords.

To learn more about this I recommend this awesome post

score 0 · Answer 2 · answered Aug 13 '18 at 13:39

You could use default arguments to make the function more flexible like:

def np_array(loc1=None, loc2=None, loc3=None):
    # ensure you don't use None type variables
    if loc1 is None:
        loc1 = 'sensibleDefaultValueGoesHere'
    # repeat as often as needed before you proceed with the

    # actual calculation ...

Generalizing my python function

2 Answers2