| # coding=utf-8 |
| # Copyright 2020 Google LLC |
| # |
| # 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. |
| |
| """Constant Value Network that always predicts a constant value.""" |
| |
| import gin |
| import tensorflow as tf |
| |
| from tf_agents.networks import network |
| from tf_agents.utils import nest_utils |
| |
| |
| @gin.configurable |
| class ConstantValueNetwork(network.Network): |
| """Constant value network that predicts zero per batch item.""" |
| |
| def __init__(self, input_tensor_spec, constant_output_val=0, name=None): |
| """Creates an instance of `ConstantValueNetwork`. |
| |
| Network supports calls with shape outer_rank + observation_spec.shape. Note |
| outer_rank must be at least 1. |
| |
| Args: |
| input_tensor_spec: A `tensor_spec.TensorSpec` or a tuple of specs |
| representing the input observations. |
| constant_output_val: A constant scalar value the network will output. |
| name: A string representing name of the network. |
| |
| Raises: |
| ValueError: If input_tensor_spec is not an instance of network.InputSpec. |
| """ |
| super(ConstantValueNetwork, self).__init__( |
| input_tensor_spec=input_tensor_spec, state_spec=(), name=name) |
| |
| self._constant_output_val = constant_output_val |
| |
| def call(self, observation, step_type=None, network_state=(), training=False): |
| shape = nest_utils.get_outer_array_shape(observation, |
| self._input_tensor_spec) |
| return tf.constant( |
| self._constant_output_val, tf.float32, shape=shape), network_state |