當我注意到我的簡單實現沒有產生正確的結果時,我正在寫一個this question的答案。雖然追捕的錯誤,我注意到以下幾點:爲什麼zip()會刪除我的生成器的值?
In [1]: import itertools
In [2]: gen = itertools.cycle((0,1,2))
In [3]: zip(gen, range(3))
Out[3]: [(0, 0), (1, 1), (2, 2)]
In [4]: zip(gen, range(3))
Out[4]: [(1, 0), (2, 1), (0, 2)]
無論出於何種原因,gen
的next()
方法被調用一個additioinal時間。 爲了說明這一點,我用了以下內容:
class loudCycle(itertools.cycle):
def next(self):
n = super(loudCycle, self).next()
print n
return n
In [6]: gen = loudCycle((0,1,2))
In [7]: zip(gen, range(3))
0
1
2
0
Out[7]: [(0, 0), (1, 1), (2, 2)]