Merge pull request #258 from 30-seconds/powerset

Add powerset

snippets/powerset.md

@@ -0,0 +1,22 @@
+---
+title: powerset
+tags: math,list,advanced
+---
+
+Returns the powerset of a given iterable.
+
+- Use the `list()` constructor to convert the given value to a `list`.
+- Use `range()` and `combinations()` to create a generator the returns all subsets.
+- Use `chain.from_iterable()` and the `list()` constructor to consume the generator and return a list.
+
+```py
+from itertools import chain, combinations
+
+def powerset(iterable):
+  s = list(iterable)
+  return list(chain.from_iterable(combinations(s, r) for r in range(len(s)+1)))
+```
+
+```py
+powerset([1, 2]) # [(), (1,), (2,), (1, 2)]
+```