Legacy Random Generation


RandomState is deprecated. You should be using numpy.random.Generator, or if you must have backward compatibility with NumPy before 1.17, numpy.random.RandomState.

The RandomState provides access to legacy generators. These all depend on normals produced using a polar transformation or inverse CDF exponentials or gammas. This class should only be used if it is essential to have randoms that are identical to what would have been produced by NumPy.

RandomState add additional information to the state which is required when using Box-Muller normals since these are produced in pairs. It is important to use get_state() when accessing the state so that these extra values are saved.

from randomgen import MT19937
from randomgen.mtrand import RandomState
from numpy.random import RandomState
   # Use same seed
rs = RandomState(12345)
mt19937 = MT19937(12345)
lg = RandomState(mt19937)

# Identical output


class randomgen.mtrand.RandomState(bit_generator=None)

Container for the Mersenne Twister pseudo-random number generator.

RandomState exposes a number of methods for generating random numbers drawn from a variety of probability distributions. In addition to the distribution-specific arguments, each method takes a keyword argument size that defaults to None. If size is None, then a single value is generated and returned. If size is an integer, then a 1-D array filled with generated values is returned. If size is a tuple, then an array with that shape is filled and returned.

Compatibility Guarantee

A fixed bit generator using a fixed seed and a fixed series of calls to ‘RandomState’ methods using the same parameters will always produce the same results up to roundoff error except when the values were incorrect. RandomState is effectively frozen and will only receive updates that are required by changes in the the internals of Numpy. More substantial changes, including algorithmic improvements, are reserved for Generator.

bit_generator{None, int, array_like, BitGenerator}, optional

Random seed used to initialize the pseudo-random number generator or an instantized BitGenerator. If an integer or array, used as a seed for the MT19937 BitGenerator. Values can be any integer between 0 and 2**32 - 1 inclusive, an array (or other sequence) of such integers, or None (the default). If seed is None, then the MT19937 BitGenerator is initialized by reading data from /dev/urandom (or the Windows analogue) if available or seed from the clock otherwise.


The Python stdlib module “random” also contains a Mersenne Twister pseudo-random number generator with a number of methods that are similar to the ones available in RandomState. RandomState, besides being NumPy-aware, has the advantage that it provides a much larger number of probability distributions to choose from.

Seeding and State


Return a tuple representing the internal state of the generator.


Set the internal state of the generator from a tuple.

Simple random data

rand(d0, d1, ..., dn)

Random values in a given shape.

randn(d0, d1, ..., dn)

Return a sample (or samples) from the "standard normal" distribution.

randint(low[, high, size, dtype])

Return random integers from low (inclusive) to high (exclusive).

random_integers(low[, high, size])

Random integers of type int between low and high, inclusive.


Return random floats in the half-open interval [0.0, 1.0).

choice(a[, size, replace, p])

Generates a random sample from a given array


Return random bytes.



Modify a sequence in-place by shuffling its contents.


Randomly permute a sequence, or return a permuted range.


beta(a, b[, size])

Draw samples from a Beta distribution.

binomial(n, p[, size])

Draw samples from a binomial distribution.

chisquare(df[, size])

Draw samples from a chi-square distribution.

dirichlet(alpha[, size])

Draw samples from the Dirichlet distribution.

exponential([scale, size])

Draw samples from an exponential distribution.

f(dfnum, dfden[, size])

Draw samples from an F distribution.

gamma(shape[, scale, size])

Draw samples from a Gamma distribution.

geometric(p[, size])

Draw samples from the geometric distribution.

gumbel([loc, scale, size])

Draw samples from a Gumbel distribution.

hypergeometric(ngood, nbad, nsample[, size])

Draw samples from a Hypergeometric distribution.

laplace([loc, scale, size])

Draw samples from the Laplace or double exponential distribution with specified location (or mean) and scale (decay).

logistic([loc, scale, size])

Draw samples from a logistic distribution.

lognormal([mean, sigma, size])

Draw samples from a log-normal distribution.

logseries(p[, size])

Draw samples from a logarithmic series distribution.

multinomial(n, pvals[, size])

Draw samples from a multinomial distribution.

multivariate_normal(mean, cov[, size, ...])

Draw random samples from a multivariate normal distribution.

negative_binomial(n, p[, size])

Draw samples from a negative binomial distribution.

noncentral_chisquare(df, nonc[, size])

Draw samples from a noncentral chi-square distribution.

noncentral_f(dfnum, dfden, nonc[, size])

Draw samples from the noncentral F distribution.

normal([loc, scale, size])

Draw random samples from a normal (Gaussian) distribution.

pareto(a[, size])

Draw samples from a Pareto II or Lomax distribution with specified shape.

poisson([lam, size])

Draw samples from a Poisson distribution.

power(a[, size])

Draws samples in [0, 1] from a power distribution with positive exponent a - 1.

rayleigh([scale, size])

Draw samples from a Rayleigh distribution.


Draw samples from a standard Cauchy distribution with mode = 0.


Draw samples from the standard exponential distribution.

standard_gamma(shape[, size])

Draw samples from a standard Gamma distribution.


Draw samples from a standard Normal distribution (mean=0, stdev=1).

standard_t(df[, size])

Draw samples from a standard Student's t distribution with df degrees of freedom.

triangular(left, mode, right[, size])

Draw samples from the triangular distribution over the interval [left, right].

uniform([low, high, size])

Draw samples from a uniform distribution.

vonmises(mu, kappa[, size])

Draw samples from a von Mises distribution.

wald(mean, scale[, size])

Draw samples from a Wald, or inverse Gaussian, distribution.

weibull(a[, size])

Draw samples from a Weibull distribution.

zipf(a[, size])

Draw samples from a Zipf distribution.