Append values to a set in Python - Stack Overflow Define a set Use add to append single values Use update to add elements from tuples, sets, lists or frozen-sets Note: Since set elements must be hashable, and lists are considered mutable, you cannot a list to a set You also cannot other sets to a set You can however, add the elements from lists and sets as demonstrated with the method
python集合可以排序吗？ - 知乎 先说结论： Python 中的集合（set）本身不能排序，但你可以 将其转化为有序的数据结构后进行排序。 1 为什么 set 不能直接排序？ Python 的 set 是一种 无序、不可重复的容器类型，设计的初衷是高效地进行成员查找、去重等集合运算（如并集、交集、差集等）。
python - How do I add two sets? - Stack Overflow Python doesn't use + for set union because it's sort of ambiguous Set union and set intersection could both be thought of as two different strategies for "adding" sets -- so by not mapping either to "+" they ensure you have to know what you're asking it to do before doing either
python - Converting a list to a set changes element order - Stack Overflow A set is an unordered data structure, so it does not preserve the insertion order CPython's set enumeration order depends on last bits of the element's hash and whether there have been key collisions during insertion This depends on your requirements If you have an normal list, and want to remove some set of elements while preserving the order of the list, you can do this with a list
python - How is set () implemented? - Stack Overflow Note: Nowadays, set and dict 's implementations have diverged significantly, so the precise behaviors (e g arbitrary order vs insertion order) and performance in various use cases differs; they're still implemented in terms of hashtables, so average case lookup and insertion remains O(1), but set is no longer just " dict, but with dummy
How can I create a Set of Sets in Python? - Stack Overflow Python's complaining because the inner set objects are mutable and thus not hashable The solution is to use frozenset for the inner sets, to indicate that you have no intention of modifying them