Check if all values of iterable are zero

user_288349 0
Viewed 98149

Is there a good, succinct/built-in way to see if all the values in an iterable are zeros? Right now I am using all() with a little list comprehension, but (to me) it seems like there should be a more expressive method. I'd view this as somewhat equivalent to a memcmp() in C.

values = (0, 0, 0, 0, 0)
# Test if all items in values tuple are zero
if all([ v == 0 for v in values ]) :
    print 'indeed they are'

I would expect a built-in function that does something like:

def allcmp(iter, value) :
    for item in iter :
        if item != value :
            return False
    return True

Does that function exist in python and I'm just blind, or should I just stick with my original version?

Update

I'm not suggesting that allcmp() is the solution. It is an example of what I think might be more meaningful. This isn't the place where I would suggest new built-ins for Python.

In my opinion, all() isn't that meaningful. It doesn't express what "all" is checking for. You could assume that all() takes an iterable, but it doesn't express what the function is looking for (an iterable of bools that tests all of them for True). What I'm asking for is some function like my allcmp() that takes two parameters: an iterable and a comparison value. I'm asking if there is a built-in function that does something similar to my made up allcmp().

I called mine allcmp() because of my C background and memcmp(), the name of my made up function is irrelevant here.

iterable python
6 Answers

The any() function may be the most simple and easy way to achieve just that. If the iterable is empty,e.g. all elements are zero, it will return False.

values = (0, 0, 0, 0, 0)
print (any(values)) # return False
user_94084510

The built-in set is given an iterable and returns a collection (set) of unique values.

So it can be used here as:

set(it) == {0}
  • assuming it is the iterable
  • {0} is a set containing only zero

More info on python set-types-set-frozenset here in docs.

user_43066080

I prefer using negation:

all(not v for v in values)
user_55397150
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