RandomGeneratorState

RandomGeneratorState[]

gives a representation of the internal state of a pseudorandom generator.

Details

  • RandomGeneratorState[] contains the generator method, method parameters and, when applicable, the full internal state.
  • A RandomGeneratorState object can be given to SeedRandom to restore the state it represents.
  • Some methods have a state that can only persist for the duration of the kernel session in which it was created.
  • The following properties can be extracted using RandomGeneratorState[]["prop"]:
  • "CrossSessionPersistent"whether the internal state persists past the current kernel session
    "Method"method name
    "StateHash"the hash of the state as an integer

Examples

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Basic Examples  (2)

Get the current state of the pseudorandom generator:

Use a RandomGeneratorState object to seed BlockRandom:

Scope  (5)

Seed the current random generator and save the resulting state:

A particular sequence of numbers is generated:

Reseed using the RandomGeneratorState object:

The same sequence of numbers is generated:

Some methods have states that can only be restored in the same session:

SeedRandom will work as expected in the same kernel session:

Trying to restore these states in a new kernel session will restore the method but not the state:

Some methods do not have a restorable state:

SeedRandom can use these to set the method, but random sequences will not be reproduced:

Programmatically extract the method name:

Programmatically determine whether the state survives the end of the kernel session:

Applications  (1)

Create a version of BlockRandom that refuses to run if the current random state cannot be restored:

Activate a randomness generation method with no restorable state:

Because this method cannot be seeded, BlockRandom cannot give reproducible results:

The function will refuse to evaluate:

Activate a randomness generation method that possesses a restorable state:

The function restores the random state at the end of each evaluation:

Hence the following result matches the previous result:

Properties & Relations  (5)

When available, the state hash is returned as an integer:

If the state hash has expired, it is returned as None:

The current random generator state is stored in $RandomGeneratorState:

SeedRandom returns a RandomGeneratorState object:

A RandomGeneratorState object can be used as a seed in SeedRandom and related functions:

Use state in SeedRandom:

Use it to seed computations in BlockRandom:

Possible Issues  (1)

When a session-only RandomGeneratorState object is given to SeedRandom, a copy is created:

This copy has a different session hash:

However, both RandomGeneratorState objects produce the same random sequences:

Wolfram Research (2020), RandomGeneratorState, Wolfram Language function, https://reference.wolfram.com/language/ref/RandomGeneratorState.html.

Text

Wolfram Research (2020), RandomGeneratorState, Wolfram Language function, https://reference.wolfram.com/language/ref/RandomGeneratorState.html.

BibTeX

@misc{reference.wolfram_2021_randomgeneratorstate, author="Wolfram Research", title="{RandomGeneratorState}", year="2020", howpublished="\url{https://reference.wolfram.com/language/ref/RandomGeneratorState.html}", note=[Accessed: 04-August-2021 ]}

BibLaTeX

@online{reference.wolfram_2021_randomgeneratorstate, organization={Wolfram Research}, title={RandomGeneratorState}, year={2020}, url={https://reference.wolfram.com/language/ref/RandomGeneratorState.html}, note=[Accessed: 04-August-2021 ]}

CMS

Wolfram Language. 2020. "RandomGeneratorState." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/RandomGeneratorState.html.

APA

Wolfram Language. (2020). RandomGeneratorState. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/RandomGeneratorState.html