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]: a out[3]: set() in [4]: type(a) out[4]: set in [5]: b = set([1, 3]) in [6]: b out[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]: b out[10]: {1, 2, 3} in [11]: b.update([4]) in [12]: b out[12]: {1, 2, 3, 4} in [13]: a.di a.difference a.difference_update a.discard in [13]: a.dif a.difference a.difference_update in [13]: a.difference(b) out[13]: set() in [14]: a out[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]: a out[18]: {4} in [19]: a.issu a.issubset a.issuperset in [19]: a.issubset(b) out[19]: true in [20]: a.remove(4) in [21]: a out[21]: set() in [22]: a.union(b) out[22]: {1, 2, 3, 4} in [23]: a out[23]: set() in [24]: b out[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]: c out[29]: set() in [30]: a out[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]: c out[33]: set() in [34]: a out[34]: {234}
常用操作3
in [35]: a.clear() in [36]: a out[36]: set() in [39]: a = {1} in [40]: b = {1, 2} in [41]: a.intersection(b) out[41]: {1} in [43]: a out[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 & b out[46]: {1} in [47]: a ^ b out[47]: {2, 3} in [48]: a - b out[48]: set() in [49]: b - a out[49]: {2, 3} in [50]: a > b out[50]: false in [51]: b > a out[51]: true in [52]: a == b out[52]: false in [53]: a != b out[53]: true
更多python中set常用操作。