Creating an empty set

Question

I have some code which tots up a set of selected values. I would like to define an empty set and add to it, but {} keeps turning into a dictionary. I have foun

Answer 1

A set literal is just a tuple of values in curly braces:

x = {2, 3, 5, 7}

So, you can create an empty set with empty tuple of values in curly braces:

x = {*()}

Still, just because you can, doesn't mean you should.

Unless it's an obfuscated programming, or a codegolf where every character matters, I'd suggest an explicit x = set() instead.

"Explicit is better than implicit."

Answer 2

As has been pointed out - the way to get an empy set literal is via set(), however, if you re-wrote your code, you don't need to worry about this, eg (and using set()):

from operator import itemgetter
query = ['four', 'two', 'three']
result = set().union(*itemgetter(*query)(inversIndex))
# set([0, 1, 2])

Answer 3

You can just construct a set:

>>> s = set()

will do the job.

Answer 4

The "proper" way to do it:

myset = set()

The {...} notation cannot be used to initialize an empty set