Source code for rlgraph.components.common.sampler
# Copyright 2018 The RLgraph authors. All Rights Reserved.
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# 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
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# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
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# See the License for the specific language governing permissions and
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# ==============================================================================
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
from rlgraph import get_backend
from rlgraph.components import Component
from rlgraph.utils.decorators import rlgraph_api
from rlgraph.utils.ops import FlattenedDataOp
from rlgraph.utils.util import get_batch_size
if get_backend() == "tf":
import tensorflow as tf
[docs]class Sampler(Component):
"""
A Sampling component can be used to sample entries from an input op, e.g.
to repeatedly perform sub-sampling.
"""
def __init__(self, sampling_strategy="uniform", scope="sampler", **kwargs):
"""
Args:
# TODO potentially pass in distribution?
sampling_strategy (str): Sampling strategy.
"""
super(Sampler, self).__init__(scope=scope, **kwargs)
self.sampling_strategy = sampling_strategy
# {1} = only flatten the 1st input arg (indexing starts from 0).
@rlgraph_api(flatten_ops={1})
def _graph_fn_sample(self, sample_size, inputs):
"""
Takes a set of input tensors and uniformly samples a subset of the
specified size from them.
Args:
sample_size (SingleDataOp[int]): Subsample size.
inputs (FlattenedDataOp): Input tensors (in a FlattenedDataOp) to sample from.
All values (tensors) should all be the same size.
Returns:
FlattenedDataOp: The sub-sampled api_methods (will be unflattened automatically).
"""
batch_size = get_batch_size(next(iter(inputs.values())))
if get_backend() == "tf":
sample_indices = tf.random_uniform(
shape=(sample_size,),
maxval=batch_size,
dtype=tf.int32
)
sample = FlattenedDataOp()
for key, tensor in inputs.items():
sample[key] = tf.gather(params=tensor, indices=sample_indices)
return sample