scipy stats.fatiguelife() | Python

Last Updated : 20 Mar, 2019

scipy.stats.fatiguelife() is an fatigue-life (Birnbaum-Sanders) continuous random variable that is defined with a standard format and some shape parameters to complete its specification.

Parameters : q : lower and upper tail probability x : quantiles loc : [optional] location parameter. Default = 0 scale : [optional] scale parameter. Default = 1 size : [tuple of ints, optional] shape or random variates. moments : [optional] composed of letters [‘mvsk’]; 'm' = mean, 'v' = variance, 's' = Fisher's skew and 'k' = Fisher's kurtosis. (default = 'mv'). Results : fatigue-life (Birnbaum-Sanders) continuous random variable

Code #1 : Creating fatigue-life continuous random variable

Python3

from scipy.stats import fatiguelife

numargs = fatiguelife.numargs
[a] = [0.7, ] * numargs
rv = fatiguelife(a)

print ("RV : \n", rv)

Output :

RV : 
 <scipy.stats._distn_infrastructure.rv_frozen object at 0x0000018D567B8400>

Code #2 : fatigue-life random variates and probability distribution.

Python3

import numpy as np
quantile = np.arange (0.01, 1, 0.1)
 
# Random Variates
R = fatiguelife.rvs(a, scale = 2,  size = 10)
print ("Random Variates : \n", R)

# PDF
R = fatiguelife.pdf(a, quantile, loc = 0, scale = 1)
print ("\nProbability Distribution : \n", R)

Output :

Random Variates : 
 [ 1.5759368   1.73788302  2.31297609  1.0005871   1.49635022 11.98492239
  2.51785146  4.0096255   0.5654246   0.97502712]

Probability Distribution : 
 [3.74431292e-278 2.59381847e-002 6.41771315e-001 9.56754833e-001
 9.63413710e-001 8.86691481e-001 7.98585419e-001 7.17860186e-001
 6.48103032e-001 5.88743459e-001]

Code #3 : Graphical Representation.

Python3

import numpy as np
import matplotlib.pyplot as plt

distribution = np.linspace(0, np.minimum(rv.dist.b, 3))
print("Distribution : \n", distribution)

plot = plt.plot(distribution, rv.pdf(distribution))

Output :

Distribution : 
 [0.         0.06122449 0.12244898 0.18367347 0.24489796 0.30612245
 0.36734694 0.42857143 0.48979592 0.55102041 0.6122449  0.67346939
 0.73469388 0.79591837 0.85714286 0.91836735 0.97959184 1.04081633
 1.10204082 1.16326531 1.2244898  1.28571429 1.34693878 1.40816327
 1.46938776 1.53061224 1.59183673 1.65306122 1.71428571 1.7755102
 1.83673469 1.89795918 1.95918367 2.02040816 2.08163265 2.14285714
 2.20408163 2.26530612 2.32653061 2.3877551  2.44897959 2.51020408
 2.57142857 2.63265306 2.69387755 2.75510204 2.81632653 2.87755102
 2.93877551 3.        ]

Code #4 : Varying Positional Arguments

Python3

import matplotlib.pyplot as plt
import numpy as np

x = np.linspace(0, 5, 100)

# Varying positional arguments
y1 = fatiguelife.pdf(x, 1, 3)
y2 = fatiguelife.pdf(x, 1, 4)
plt.plot(x, y1, "*", x, y2, "r--")