在列表中查找下一个最接近的数字

Question

I have a list:

lst = [100, 210, 330, 460, 600, 750, 910, 1080, 1260]

and a given number 470

I want to find the next upper bound of the interval between its two closest numbers... This would give 600 because it is the next closest number.

If it were 670 I would get 750 .

I have lst[min(range(len(lst)), key = lambda i: abs(lst[i]-K))] which is giving the closet number regardless if it is the upper bound.

Answer 1

You can use bisect.bisect_left which gives you the left most insertion index (given the list is sorted which your post seems to indicate it is) in logarithmic time:

from bisect import bisect_left

A[bisect_left(A, 460)]
460
>>> A[bisect_left(A, 470)]
600
>>> A[bisect_left(A, 670)]
750

This will raise an IndexError for numbers greater than 1260 .

Answer 2

filter(lambda x: x>=460, A).__next__() # 460 filter(lambda x: x>=470, A).__next__() # 600 filter(lambda x: x>=670, A).__next__() # 750