遍歷一組/遺蹟Python的方式設置

Question

是什麼做的清潔方法如下：

def foo(aSet) : 
    for a in aSet: 
     for remaining in aSet - {a} : 
      doSomething(a,remaining) 

我想必須有書面證明爲只是一個for循環的一些方法？

Answer 1

aSet = {1,2,3} 
[[i,j] for i in aSet for j in aSet if j != i] 
#=> [[1, 2], [1, 3], [2, 1], [2, 3], [3, 1], [3, 2]] 

在你的情況，你需要一臺發電機

變量名需要更換，以類似的東西實際值的

(doSomething(i, j) for i in aSet for j in aSet if j != i) 

Answer 2

>>> from itertools import permutations 
>>> aSet = {1, 2, 3} 
>>> list(permutations(aSet, 2)) 
[(1, 2), (1, 3), (2, 1), (2, 3), (3, 1), (3, 2)] 

>>> for a, remaining in permutations(aSet, 2): 
...  print(a, remaining, end=', ') 
... 
1 2, 1 3, 2 1, 2 3, 3 1, 3 2,