CODEWITHSUNDEEP
python
tomcajot
tomcajot

Reputation: 193

Count of used parameters

I have a function that takes multiple lists as input. I'm counting the number of them that are active parameters (not None). I'm currently doing it like this:

def x(l1, l2, l3):
    …
    count = 0
    if l1:
        count += 1
    if l2:
        count += 1
    if l3:
        count += 1
    …

Isn't there a better (and prettier) way for doing this?

Upvotes: 0

Views: 96

Answers (2)

Tomerikoo
Tomerikoo

Reputation: 19414

Usually, when you have such a repeating pattern with one very slight difference - a loop is in place:

def x(l1, l2, l3):
    …
    count = 0
    for l in [l1, l2, l3]:
        if l:
            count += 1
    …

This makes the code more verbose because if more lists (arguments) are added, you only need to add them once to the list in the loop, instead of adding a new if statement for each one...

This was intended to be as similar as your original code as possible. For a shorter, more "pythonic" code, see @Samwise's answer.

Upvotes: 1

Samwise
Samwise

Reputation: 71477

If you want your function to take an arbitrary number of args, it gets a lot neater:

def x(*args):
    count = sum(bool(arg) for arg in args)
    ...

Otherwise you could reconstruct the equivalent of args based on the named parameters:

def x(l1, l2, l3):
    …
    count = sum(bool(arg) for arg in (l1, l2, l3))
    …

Note that bool(arg) has the same behavior as your if l1: ... checks -- it converts a "truthy" arg to True (which counts as 1 when you sum it). If you wanted to check specifically for None (as opposed to an empty list or any other "falsey" arg) you'd do arg is not None.

Upvotes: 3

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