# coding=utf-8
# Copyright 2020 The Google Research Authors.
#
# 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
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"""Utility functions for jax pytree manipulations."""

import jax
from jax import numpy as jnp


def tree_add(a, b):
  return jax.tree_multimap(lambda e1, e2: e1+e2, a, b)


def tree_dot(a, b):
  return sum([jnp.sum(e1 * e2) for e1, e2 in
              zip(jax.tree_leaves(a), jax.tree_leaves(b))])


def tree_dist(a, b):
  dist_sq = sum([jnp.sum((e1 - e2)**2) for e1, e2 in
                 zip(jax.tree_leaves(a), jax.tree_leaves(b))])
  return jnp.sqrt(dist_sq)


def tree_scalarmul(a, s):
  return jax.tree_map(lambda e: e*s, a)
