* 作者：煮酒品茶 tea * 博客：http://www.zwhset.com http://cwtea.blog.51cto.com * 目前在京峰教育担任python讲师 # 0、不可变集合frozenset > frozenset是不可变的集合, 简单说就是不能修改的set集合, 它和set集合类似，区别在于一个可变, 另一个不可变，其它的功能一样。 很像list和tuple的区别 # 1、函数原型 ~~~ frozenset() -> empty frozenset object # 创建空的 frozense集合 frozenset(iterable) -> frozenset object # 从一个iterable转换成frozense集合 difference(...) Return the difference of two or more sets as a new set. (i.e. all elements that are in this set but not the others.) intersection(...) Return the intersection of two or more sets as a new set. (i.e. elements that are common to all of the sets.) isdisjoint(...) Return True if two sets have a null intersection. issubset(...) # 子集判断 Report whether another set contains this set. issuperset(...) # 父集判断 Report whether this set contains another set. symmetric_difference(...) Return the symmetric difference of two sets as a new set. (i.e. all elements that are in exactly one of the sets.) union(...) # 并集 Return the union of sets as a new set. ~~~ # 2、样例 ~~~ >>> frozen_set = frozenset() # 创建一个空的frozenset集合 >>> frozen_set frozenset([]) >>> >>> frozen_set2 = frozenset('abcdefghigkomnopqrszuvwxyz') # 从一个str创建一个frozenset集合 >>> frozen_set2 frozenset(['a', 'c', 'b', 'e', 'd', 'g', 'f', 'i', 'h', 'k', 'm', 'o', 'n', 'q', 'p', 's', 'r', 'u', 'w', 'v', 'y', 'x', 'z']) >>> >>> frozen_set2 = frozenset(['a','b','c','d','e']) # 从一个list创建一个frozenset集合 >>> frozen_set2 frozenset(['a', 'c', 'b', 'e', 'd']) ~~~ # 3、应用场景: 如果要创建和使用一个不会修改的集合可以用frozenset, 能用不可变的对就用不可变的对象