Difference between np.random.seed() and np.random.RandomState()

Question

I know that to seed the randomness of numpy.random, and be able to reproduce it, I should us:

import numpy as np
np.random.seed(1234)

but w

Answer 1

np.random.RandomState() constructs a random number generator. It does not have any effect on the freestanding functions in np.random, but must be used explicitly:

>>> rng = np.random.RandomState(42)
>>> rng.randn(4)
array([ 0.49671415, -0.1382643 ,  0.64768854,  1.52302986])
>>> rng2 = np.random.RandomState(42)
>>> rng2.randn(4)
array([ 0.49671415, -0.1382643 ,  0.64768854,  1.52302986])