numpy.random.SeedSequence#
- class numpy.random.SeedSequence(entropy=None, *, spawn_key=(), pool_size=4)#
SeedSequence mixes sources of entropy in a reproducible way to set the initial state for independent and very probably non-overlapping BitGenerators.
Once the SeedSequence is instantiated, you can call the
generate_state
method to get an appropriately sized seed. Callingspawn(n)
will createn
SeedSequences that can be used to seed independent BitGenerators, i.e. for different threads.- Parameters:
- entropy{None, int, sequence[int]}, optional
The entropy for creating a
SeedSequence
.- spawn_key{(), sequence[int]}, optional
An additional source of entropy based on the position of this
SeedSequence
in the tree of such objects created with theSeedSequence.spawn
method. Typically, onlySeedSequence.spawn
will set this, and users will not.- pool_size{int}, optional
Size of the pooled entropy to store. Default is 4 to give a 128-bit entropy pool. 8 (for 256 bits) is another reasonable choice if working with larger PRNGs, but there is very little to be gained by selecting another value.
- n_children_spawned{int}, optional
The number of children already spawned. Only pass this if reconstructing a
SeedSequence
from a serialized form.
Notes
Best practice for achieving reproducible bit streams is to use the default
None
for the initial entropy, and then useSeedSequence.entropy
to log/pickle theentropy
for reproducibility:>>> sq1 = np.random.SeedSequence() >>> sq1.entropy 243799254704924441050048792905230269161 # random >>> sq2 = np.random.SeedSequence(sq1.entropy) >>> np.all(sq1.generate_state(10) == sq2.generate_state(10)) True
- Attributes:
- entropy
- n_children_spawned
- pool
- pool_size
- spawn_key
- state
Methods
generate_state
(n_words[, dtype])Return the requested number of words for PRNG seeding.
spawn
(n_children)Spawn a number of child
SeedSequence
s by extending thespawn_key
.