File size: 2,091 Bytes
09d8e80 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 | # Copyright 2019 DeepMind Technologies Limited. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# ==============================================================================
"""Utilities to generate random pytrees."""
from typing import Callable
import chex
import jax
from jax import tree_util as jtu
from optax._src import base
def _tree_rng_keys_split(
rng_key: chex.PRNGKey, target_tree: chex.ArrayTree
) -> chex.ArrayTree:
"""Split keys to match structure of target tree.
Args:
rng_key: the key to split.
target_tree: the tree whose structure to match.
Returns:
a tree of rng keys.
"""
tree_def = jtu.tree_structure(target_tree)
keys = jax.random.split(rng_key, tree_def.num_leaves)
return jtu.tree_unflatten(tree_def, keys)
def tree_random_like(
rng_key: chex.PRNGKey,
target_tree: chex.ArrayTree,
sampler: Callable[
[chex.PRNGKey, base.Shape], chex.Array
] = jax.random.normal,
) -> chex.ArrayTree:
"""Create tree with random entries of the same shape as target tree.
Args:
rng_key: the key for the random number generator.
target_tree: the tree whose structure to match. Leaves must be arrays.
sampler: the noise sampling function, by default ``jax.random.normal``.
Returns:
a random tree with the same structure as ``target_tree``, whose leaves have
distribution ``sampler``.
.. versionadded:: 0.2.1
"""
keys_tree = _tree_rng_keys_split(rng_key, target_tree)
return jtu.tree_map(
lambda l, k: sampler(k, l.shape),
target_tree,
keys_tree,
)
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