我试图在元组列表中添加一个新元组(按元组中的第一个元素排序),其中新元组包含列表中上一个元素和下一个元素的元素.
例：
- oldList = [(3,10),(4,7),(5,5)]
- newList = [(3,5)]
(4,10)由(3,10)和(4,7)之间构建并添加.
- Construct (x,y) from (a,y) and (x,b)
我已经尝试使用枚举()插入到特定的位置,但这并不真正让我访问下一个元素.
解决方法
- oldList = [(3,5)]
- def pair(lst):
- # create two iterators
- it1,it2 = iter(lst),iter(lst)
- # move second to the second tuple
- next(it2)
- for ele in it1:
- # yield original
- yield ele
- # yield first ele from next and first from current
- yield (next(it2)[0],ele[1])
哪个会给你：
- In [3]: oldList = [(3,5)]
- In [4]: list(pair(oldList))
- Out[4]: [(3,5)]
显然,我们需要做一些错误处理来处理不同的可能情况.
如果您愿意,也可以使用单个迭代器：
- def pair(lst):
- it = iter(lst)
- prev = next(it)
- for ele in it:
- yield prev
- yield (prev[0],ele[1])
- prev = ele
- yield (prev[0],ele[1])
您可以使用itertools.tee代替调用iter：
- from itertools import tee
- def pair(lst):
- # create two iterators
- it1,it2 = tee(lst)
- # move second to the second tuple
- next(it2)
- for ele in it1:
- # yield original
- yield ele
- # yield first ele from next and first from current
- yield (next(it2)[0],ele[1])