ast_toolbox.utils.seeding module

ast_toolbox.utils.seeding.create_seed(a=None, max_bytes=8)

Create a strong random seed. Otherwise, Python 2 would seed using the system time, which might be non-robust especially in the presence of concurrency.

Args:

a (Optional[int, str]): None seeds from an operating system specific randomness source. max_bytes: Maximum number of bytes to use in the seed.

ast_toolbox.utils.seeding.hash_seed(seed=None, max_bytes=8)

Any given evaluation is likely to have many PRNG’s active at once. (Most commonly, because the environment is running in multiple processes.) There’s literature indicating that having linear correlations between seeds of multiple PRNG’s can correlate the outputs:

http://blogs.unity3d.com/2015/01/07/a-primer-on-repeatable-random-numbers/ http://stackoverflow.com/questions/1554958/how-different-do-random-seeds-need-to-be http://dl.acm.org/citation.cfm?id=1276928

Thus, for sanity we hash the seeds before using them. (This scheme is likely not crypto-strength, but it should be good enough to get rid of simple correlations.)

Args:

seed (Optional[int]): None seeds from an operating system specific randomness source. max_bytes: Maximum number of bytes to use in the hashed seed.

ast_toolbox.utils.seeding.np_random(seed=None)