浅谈python中set使用

            
In [2]: a = set()  # 常用操作1 
 
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) 

            
               in 
              
                () 
----> 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]:
              
            
          

            
In [16]: a.add({1, 3}) 
---------------------------------------------------------------------------
TypeError                 Traceback (most recent call last) 

            
               in 
              
                () 
----> 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) 

                
                   in 
                  
                    () 
----> 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) 

                    
                       in 
                      
                        () 
----> 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}
                      
                    
                  
                
              
            
          

            
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}
            

            

             
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11 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