Count longest streak of >0 in a Python list Python

Question

I have a list of float values, something like [-2.4, -1.3, -3.8, -1.9, 5.0, 0.6, 2.9, 1.9, 4.7, 3.5, 6.9, 1.5, -4.2, 3.7, 2.1, 6.6, 7.0, -4.6, -4.9].

What I need and trying to do is count the longest streak of values >0.

Tried doing it through for loop, but it gives only a total count, and through itertools.groupby, but I'm still getting only values.

for i, x in groupby(mintemps):
    if float(i >= 0):
        print(len(list(x)))

Any help would be greatly appreciated.

Answer 1

If you use numpy and itertools this turns out to be pretty fast ,

I converted the list to a boolean array in which the values are indicated if an element in greater than 0 and thne fed it to itertools.groupby to get its maximum consecutive value , the bit value is True or False.

import numpy as np
import itertools
narr=np.array([-2.4, -1.3, -3.8, -1.9, 5.0, 0.6, 2.9, 1.9, 4.7, 3.5, 6.9, 1.5, -4.2, 3.7, 2.1, 6.6, 7.0, -4.6, -4.9])

def max_runs_of_ones(bits):
    maxvalue=0
    for bit, group in itertools.groupby(bits):
        if bit: 
            maxvalue=max(maxvalue,sum(group))
    return maxvalue
print(narr)

print("maximum value is",max_runs_of_ones(narr>0))

OUTPUT

[-2.4 -1.3 -3.8 -1.9  5.   0.6  2.9  1.9  4.7  3.5  6.9  1.5 -4.2  3.7
  2.1  6.6  7.  -4.6 -4.9]

maximum value is 8