Suppose I have a large vector of integers ranging from 1 to 5. Now suppose I want to compute the average length of streaks of say, the number 5, where a single appearance of “5” before a different number appears, is counted as a streak of 1.

So, for example, for the vector [1,2,5,5,1,5,3,5,5,5], the average streak-length of the number 5 is (2 + 1 + 3) / 3 = 2

What is an efficient way to compute the average length of streaks of a given number in Julia?

I would just take the naive approach with a simple, straight for loop:

function count_streak(pred::Function, itr)
n_streaks, cumlen, len = 0, 0, 0
reset(n_streaks, cumlen, len) = (n_streaks+1, cumlen+len, 0)
for i in itr
if pred(i)
len += 1
else
if len > 0
(n_streaks, cumlen, len) = reset(n_streaks, cumlen, len)
end
end
end
if len > 0
(n_streaks, cumlen, len) = reset(n_streaks, cumlen, len)
end
cumlen / n_streaks
end