find the length of the longest consecutive series of numbers [duplicate]

Answer 1

In pure Python

>>> from itertools import groupby
>>> L = [1,1,1,-1,-1,1,-1,1,1,-1,-1,-1,1,-1]
>>> max(sum(1 for i in g) for k,g in groupby(L))
3

Answer 2

Similar to the answer by @AlexMartelli

>>> import numpy as np
>>> nums = np.array([1,1,1,-1-1,1,-1,1,1,-1,-1,-1,1,-1])
>>> run_ends = np.where(np.diff(nums))[0] + 1
>>> np.diff(np.hstack((0, run_ends, nums.size))).max()
3