Returning boolean if set is empty

Question

I am struggling to find a more clean way of returning a boolean value if my set is empty at the end of my function

I take the intersection of two sets, and want to return True or False based on if the resulting set is empty.

def myfunc(a,b):     c = a.intersection(b)     #...return boolean here 

My initial thought was to do

return c is not None 

However, in my interpreter I can easily see that statement will return true if c = set([])

>>> c = set([]) >>> c is not None True 

I've also tried all of the following:

>>> c == None False >>> c == False False >>> c is None False 

Now I've read from the documentation that I can only use and, or, and not with empty sets to deduce a boolean value. So far, the only thing I can come up with is returning not not c

>>> not not c False >>> not c True 

I have a feeling there is a much more pythonic way to do this, by I am struggling to find it. I don't want to return the actual set to an if statement because I don't need the values, I just want to know if they intersect.

Answer 1

not as pythonic as the other answers, but mathematics:

return len(c) == 0 

---

As some comments wondered about the impact len(set) could have on complexity. It is O(1) as shown in the source code given it relies on a variable that tracks the usage of the set.

static Py_ssize_t set_len(PyObject *so) {     return ((PySetObject *)so)->used; } 

Answer 2

def myfunc(a,b):     c = a.intersection(b)     return bool(c) 

bool() will do something similar to not not, but more ideomatic and clear.