random.expovariate() function in Python

random module is used to generate random numbers in Python. Not actually random, rather this is used to generate pseudo-random numbers. That implies that these randomly generated numbers can be determined.

random.expovariate()

expovariate() is an inbuilt method of the random module. It is used to return a random floating point number with exponential distribution.

Syntax : random.expovariate(lambda)

Parameters :
lambda : a non zero value

Returns : a random exponential distribution floating number
if the parameter is positive, the results range from 0 to positive infinity
if the parameter is negative, the results range from 0 to negative infinity

Example 1:

# import the random module
import random

# determining the values of the parameter
lambda = 1.5

# using the expovariate() method
print(random.expovariate(lambda))

Output :

0.22759592233982198

Example 2: We can generate the number multiple times and plot a graph to observe the exponential distribution.

# import the required libraries
import random
import matplotlib.pyplot as plt

# store the random numbers in a
# list
nums = []
alpha = 3

for i in range(100):
    temp = random.paretovariate(alpha)
    nums.append(temp)

# plotting a graph
plt.plot(nums)
plt.show()

Output :

Example 3: We can create a histogram to observe the density of the exponential distribution.

# import the required libraries
import random
import matplotlib.pyplot as plt

# store the random numbers in a list
nums = []
lambda = 1.5

for i in range(10000):
    temp = random.expovariate(lambda)
    nums.append(temp)

# plotting a graph
plt.hist(nums, bins = 200)
plt.show()

Output :