Help on class frozenset in module __builtin__:
class frozenset(object)
| frozenset() -> empty frozenset object
| frozenset(iterable) -> frozenset object
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| Build an immutable unordered collection of unique elements.
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| Methods defined here:
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| __and__(...)
| x.__and__(y) <==> x&y
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| __cmp__(...)
| x.__cmp__(y) <==> cmp(x,y)
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| __contains__(...)
| x.__contains__(y) <==> y in x.
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| __eq__(...)
| x.__eq__(y) <==> x==y
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| __ge__(...)
| x.__ge__(y) <==> x>=y
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| __getattribute__(...)
| x.__getattribute__('name') <==> x.name
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| __gt__(...)
| x.__gt__(y) <==> x>y
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| __hash__(...)
| x.__hash__() <==> hash(x)
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| __iter__(...)
| x.__iter__() <==> iter(x)
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| __le__(...)
| x.__le__(y) <==> x<=y
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| __len__(...)
| x.__len__() <==> len(x)
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| __lt__(...)
| x.__lt__(y) <==> x | | __ne__(...) | x.__ne__(y) <==> x!=y | | __or__(...) | x.__or__(y) <==> x|y | | __rand__(...) | x.__rand__(y) <==> y&x | | __reduce__(...) | Return state information for pickling. | | __repr__(...) | x.__repr__() <==> repr(x) | | __ror__(...) | x.__ror__(y) <==> y|x | | __rsub__(...) | x.__rsub__(y) <==> y-x | | __rxor__(...) | x.__rxor__(y) <==> y^x | | __sizeof__(...) | S.__sizeof__() -> size of S in memory, in bytes | | __sub__(...) | x.__sub__(y) <==> x-y | | __xor__(...) | x.__xor__(y) <==> x^y | | copy(...) | Return a shallow copy of a set. | | 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(...) | Report whether another set contains this set. | | issuperset(...) | 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(...) | Return the union of sets as a new set. | | (i.e. all elements that are in either set.) | | ---------------------------------------------------------------------- | Data and other attributes defined here: | | __new__ = | T.__new__(S, ...) -> a new object with type S, a subtype of T class frozenset([iterable]) Return a new frozenset object, optionally with elements taken from iterable. frozenset is a built-in class. See frozenset and Set Types — set, frozenset for documentation about this class. For other containers see the built-in set, list, tuple, and dict classes, as well as the collections module. 中文说明： 本函数是返回一个冻结的集合。所谓冻结就是这个集合不能再添加或删除任何集合里的元素。 它是不可变的，存在哈希值，好处是它可以作为字典的key，也可以作为其它集合的元素。缺点是一旦创建便不能更改，没有add，remove方法。 >>> y=[1,2,3,4,5,6,7,8,9] >>> print(len(y),y) (9, [1, 2, 3, 4, 5, 6, 7, 8, 9]) >>> set=frozenset(y) >>> print(len(set),set) (9, frozenset([1, 2, 3, 4, 5, 6, 7, 8, 9])) >>> t=frozenset('bookshop') >>> t frozenset(['b', 'h', 'k', 'o', 'p', 's']) >>> t=frozenset('bookshop') >>> t frozenset(['b', 'h', 'k', 'o', 'p', 's']) >>> for i in t: ... print(i) ... b h k o p s