unitproc/python/sleepRand.py

   1 #!/usr/bin/env python3
   2 # Desc: Pauses a random amount of time. Random distribution is inverse gaussian.
   3 # Version: 0.0.3
   4 # Depends: python 3.7.3
   5 # Usage: ./sleepRand.py arg1
   6 # Input: arg1: float seconds (mean of inverse gaussian distribution)
   7 # Example: python3 sleepRand.py 4.0
   8
   9 import math, time, random, sys
  10
  11 # Adjustments
  12 lambdaFactor = 4; # spread factor; inversely proportional to variance
  13
  14 # Define functions
  15 def randInvGau(mu, lam):
  16     """Returns random variate of inverse gaussian distribution"""
  17     # input: mu:  mean of inverse gaussian distribution
  18     #        lam: shape parameter
  19     # output: float sampled from inv. gaus. with range 0 to infinity, mean mu
  20     # example: sample = float(randInvGau(1.0,4.0));
  21     # Ref/Attrib: doi:10.1080/00031305.1976.10479147
  22     nu = random.gauss(0,1);
  23     y = nu ** 2;
  24     xTerm1 = mu;
  25     xTerm2 = mu ** 2 * y / (2 * lam);
  26     xTerm3 = (- mu / (2 * lam)) * math.sqrt(4 * mu * lam * y + mu ** 2 * y ** 2);
  27     x = xTerm1 + xTerm2 + xTerm3;
  28     z = random.uniform(0.0,1.0);
  29     if z <= (mu / (mu + x)):
  30         return x;
  31     else:
  32         return (mu ** 2 / x);
  33
  34 # Check input (TODO)
  35 arg1 = float(sys.argv[1]); # first argument
  36 desMean = arg1;
  37
  38 # Calculate delay
  39 delay = randInvGau(desMean, desMean * lambdaFactor);
  40 #print('DEBUG:delay:' + str(float(delay)));
  41
  42 # Sleep
  43 time.sleep(float(delay));
  44
  45 # Author: Steven Baltakatei Sandoal
  46 # License: GPLv3+