弦的组合

Question

我有一个变量如下：

symbols = ['KEL','BYCO']

我想要一个函数，将这些符号的组合作为输出，如下所示

['KEL'],['BYCO'] and ['KEL','BYCO']

如果一个变量中包含n个字符串，有没有人能推荐一个库/函数来实现这样的组合呢。你知道吗

Answer 1

我想这就是你想要的：

Python 2.7.6 (default, Oct 26 2016, 20:30:19)                                                                                                                                                                                                                                  
[GCC 4.8.4] on linux2                                                                                                                                                                                                                                                          
Type "help", "copyright", "credits" or "license" for more information.                                                                                                                                                                                                         
>>>                                                                                                                                                                                                                                                                            
>>> from itertools import combinations, chain                                                                                                                                                                                                                                  
>>>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                
>>> def powerset(iterable):                                                                                                                                                                                                                                                    
...     "powerset([1,2,3])  > () (1,) (2,) (3,) (1,2) (1,3) (2,3) (1,2,3)"                                                                                                                                                                                                    
...     s = list(iterable)                                                                                                                                                                                                                                                     
...     return chain.from_iterable(combinations(s, r) for r in range(len(s)+1))                                                                                                                                                                                                
...                                                                                                                                                                                                                                                                            
>>> symbols = ['KEL','BYCO']
>>>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           
>>> list(powerset(symbols))                                                                                                                                                                                                                                                  
[(), ('KEL',), ('BYCO',), ('KEL', 'BYCO')]

这里的powerset函数直接从文档中提取：https://docs.python.org/2/library/itertools.html