sets 支持 x in set, len(set),和 for x in set。作为一个无序的集合，sets不记录元素位置或者插入点。因此，sets不支持 indexing, slicing, 或其它类序列（sequence-like）的操作。

下面我们通过几个例子，来简单说明下

常用操作1

In [2]: a = set() In [3]: aOut[3]: set() In [4]: type(a)Out[4]: set In [5]: b = set([1, 3]) In [6]: bOut[6]: {1, 3} In [7]: type(b)Out[7]: set In [8]: b.update(2)---------------------------------------------------------------------------TypeError Traceback (most recent call last)<ipython-input-8-d51e2fe4c50a> in <module>()----> 1 b.update(2) TypeError: 'int' object is not iterable In [9]: b.update({2}) In [10]: bOut[10]: {1, 2, 3} In [11]: b.update([4]) In [12]: bOut[12]: {1, 2, 3, 4} In [13]: a.dia.difference a.difference_update a.discard In [13]: a.difa.difference a.difference_update In [13]: a.difference(b)Out[13]: set() In [14]: aOut[14]: set() In [15]: b.difference(a)Out[15]: {1, 2, 3, 4} In [16]:

常用操作2

In [16]: a.add({1, 3})---------------------------------------------------------------------------TypeError Traceback (most recent call last)<ipython-input-16-98cdf4d0875e> in <module>()----> 1 a.add({1, 3}) TypeError: unhashable type: 'set' In [17]: a.add(4) In [18]: aOut[18]: {4} In [19]: a.issua.issubset a.issuperset In [19]: a.issubset(b)Out[19]: True In [20]: a.remove(4) In [21]: aOut[21]: set() In [22]: a.union(b)Out[22]: {1, 2, 3, 4} In [23]: aOut[23]: set() In [24]: bOut[24]: {1, 2, 3, 4} In [25]: b.pop()Out[25]: 1 In [26]: a.copy(b)---------------------------------------------------------------------------TypeError Traceback (most recent call last)<ipython-input-26-9e8a5f057ffd> in <module>()----> 1 a.copy(b) TypeError: copy() takes no arguments (1 given) In [27]: a.copy()Out[27]: set() In [28]: c = a.copy() In [29]: cOut[29]: set() In [30]: aOut[30]: set() In [31]: a.add({234})---------------------------------------------------------------------------TypeError Traceback (most recent call last)<ipython-input-31-6073e02d68a9> in <module>()----> 1 a.add({234}) TypeError: unhashable type: 'set' In [32]: a.add(234) In [33]: cOut[33]: set() In [34]: aOut[34]: {234}

常用操作3

In [35]: a.clear() In [36]: aOut[36]: set() In [39]: a = {1} In [40]: b = {1, 2} In [41]: a.intersection(b)Out[41]: {1} In [43]: aOut[43]: {1} In [44]: b = {1, 2, 3} In [45]: a.union(b)Out[45]: {1, 2, 3} In [45]: a.union(b)Out[45]: {1, 2, 3} In [46]: a & bOut[46]: {1} In [47]: a ^ bOut[47]: {2, 3} In [48]: a - bOut[48]: set() In [49]: b - aOut[49]: {2, 3}In [50]: a > bOut[50]: False In [51]: b > aOut[51]: True In [52]: a == bOut[52]: False In [53]: a != bOut[53]: True