stats.py

import sys
import math


def average(li): 
    return sum(li) * 1.0 / len(li)


def stddev(numbers):    
    avg = average(numbers)
    variance = map(lambda x: (x - avg)**2, numbers)
    
    return math.sqrt(average(variance))


def percentile(numbers, percent):
    
    k = (len(numbers)-1) * (percent / 100.0)
    f = math.floor(k)
    c = math.ceil(k)
    if f == c:
        return numbers[int(k)]
    
    d0 = numbers[int(f)] * (c-k)
    d1 = numbers[int(c)] * (k-f)
    
    return d0+d1


if __name__ == '__main__':
    filename = sys.argv[1]
    numbers = [float(line.replace(' secs', '').strip()) for line in open(filename)]
    
    
    print "Standard Deviation: %f" % stddev(numbers)
    print "90th percentile: %f" % percentile(numbers, 90)