How to Generate All Subsets of a Set Using Python's `itertools.combinations`?

How to Generate All Subsets of a Set Using itertools.combinations

In Python, the itertools.combinations module provides a simple and efficient method for generating the powerset of a set. Here's how you can do it:

from itertools import chain, combinations

def powerset(iterable):
    "powerset([1,2,3]) --> () (1,) (2,) (3,) (1,2) (1,3) (2,3) (1,2,3)"
    s = list(iterable)
    return chain.from_iterable(combinations(s, r) for r in range(len(s)+1))

For example, to find all the subsets of the set {0, 1, 2, 3}, you would use the following code:

>>> list(powerset([0, 1, 2, 3]))
[(), (0,), (1,), (2,), (3,), (0, 1), (0, 2), (0, 3), (1, 2), (1, 3), (2, 3), (0, 1, 2), (0, 1, 3), (0, 2, 3), (1, 2, 3), (0, 1, 2, 3)]

Note that the empty tuple () is included in the powerset, as it represents the empty subset.

If you prefer not to have the empty tuple in the results, you can modify the range in the combinations loop as follows:

def powerset(iterable):
    "powerset([1,2,3]) --> () (1,) (2,) (3,) (1,2) (1,3) (2,3) (1,2,3)"
    s = list(iterable)
    return chain.from_iterable(combinations(s, r) for r in range(1, len(s)+1))

This will exclude the empty tuple from the returned subsets.

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