Set vs. set python

Question

What's the difference between set("a") and sets.Set("a")? Their types are different, but they seem to do the same thing.

I can't find any resources online about it, but I've seen both used in examples.

Answer 1

You've tagged this Python 3, so the difference is that sets doesn't exist. Use set.

In Python 2, the difference is that sets is deprecated. It's the old, slow, not-as-good version. Use set. This is explained in the documentation for the sets module, which comes up instantly on a search for Python sets.

Answer 2

The built in set() was based on the old sets.Set() and runs faster.
Both 'do' the same thing, though in Python 3 the 'sets' module no longer exists.

Here is the answer directly from The Python 2 Library:
The built-in set and frozenset types were designed based on lessons learned from the sets module. The key differences are:

Set and ImmutableSet were renamed to set and frozenset.

- There is no equivalent to BaseSet. Instead, use isinstance(x, (set, frozenset)).

- The hash algorithm for the built-ins performs significantly better (fewer collisions) for most datasets.

- The built-in versions have more space efficient pickles.

- The built-in versions do not have a union_update() method. Instead, use the update() method which is equivalent.

- The built-in versions do not have a _repr(sorted=True) method. Instead, use the built-in repr() and sorted() functions: repr(sorted(s)).

- The built-in version does not have a protocol for automatic conversion to immutable. Many found this feature to be confusing and no one in the community reported having found real uses for it.