what is numpy random.RandomState

Question

import numpy as np 
rng=np.random.RandomState(123)
for i in np.arange(1,21):
    number=2**i
    heads_tails=rng.randint(0,2,size=number)
    ptails=np.mean(heads_tails)
    print("Number of tosses:",number,"---","Probability of Tails:%.2f"%(ptails*100),"%","---",
         "Probabilty of Heads:%.2f"%(100-ptails*100),"%")

Hi,I wrote this code and I didn't understand the random.RandomState's function in here,What is it using for or What is the function of that? If you can explain,I would be appreciated.

Answer 1

np.random.RandomState() constructs a random number generator. np.random.RandomState() returns a new seeded RandomState instance but otherwise does not change anything. You have to use the returned RandomState instance to get consistent pseudorandom numbers.

For instance, if you use the functions in the numpy.random you will not get consistent pseudorandom numbers because they are pulling from a different RandomState instance than the one you just created. So to be consistent, you can create a specific RandomState and draw to pseudorandom numbers in a reproducible way.