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# Copyright 2018 Amazon.com, Inc. or its affiliates. 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.
# A copy of the License is located at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# or in the "license" file accompanying this file. This file 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.
# Standard library imports
from typing import List, Optional
# Third-party imports
from mxnet.gluon import HybridBlock
# First-party imports
from gluonts.core.component import validated
from gluonts.distribution import DistributionOutput, StudentTOutput
from gluonts.model.estimator import GluonEstimator
from gluonts.model.predictor import Predictor, RepresentableBlockPredictor
from gluonts.support.util import copy_parameters
from gluonts.time_feature.lag import (
TimeFeature,
get_lags_for_frequency,
time_features_from_frequency_str,
)
from gluonts.trainer import Trainer
from gluonts.transform import (
AddAgeFeature,
AddObservedValuesIndicator,
AddTimeFeatures,
AsNumpyArray,
Chain,
ExpectedNumInstanceSampler,
FieldName,
InstanceSplitter,
RemoveFields,
SetField,
Transformation,
VstackFeatures,
)
# Relative imports
from ._network import DeepARPredictionNetwork, DeepARTrainingNetwork
class DeepAREstimator(GluonEstimator):
"""
Construct a DeepAR estimator.
This implements an RNN-based model, close to the one described in
[SFG17]_.
*Note:* the code of this model is unrelated to the implementation behind
`SageMaker's DeepAR Forecasting Algorithm
<https://docs.aws.amazon.com/sagemaker/latest/dg/deepar.html>`_.
Parameters
----------
freq
Frequency of the data to train on and predict
prediction_length
Length of the prediction horizon
trainer
Trainer object to be used (default: Trainer())
context_length
Number of steps to unroll the RNN for before computing predictions
(default: None, in which case context_length = prediction_length)
num_layers
Number of RNN layers (default: 2)
num_cells
Number of RNN cells for each layer (default: 40)
cell_type
Type of recurrent cells to use (available: 'lstm' or 'gru';
default: 'lstm')
dropout_rate
Dropout regularization parameter (default: 0.1)
use_feat_dynamic_real
Whether to use the ``feat_dynamic_real`` field from the data
(default: False)
use_feat_static_cat
Whether to use the ``feat_static_cat`` field from the data
(default: False)
cardinality
Number of values of each categorical feature.
This must be set if ``use_feat_static_cat == True`` (default: None)
embedding_dimension
Dimension of the embeddings for categorical features (the same
dimension is used for all embeddings, default: 5)
distr_output
Distribution to use to evaluate observations and sample predictions
(default: StudentTOutput())
scaling
Whether to automatically scale the target values (default: true)
lags_seq
Indices of the lagged target values to use as inputs of the RNN
(default: None, in which case these are automatically determined
based on freq)
time_features
Time features to use as inputs of the RNN (default: None, in which
case these are automatically determined based on freq)
num_parallel_samples
Number of evaluation samples per time series to increase parallelism during inference.
This is a model optimization that does not affect the accuracy (default: 100)
"""
@validated()
def __init__(
self,
freq: str,
prediction_length: int,
trainer: Trainer = Trainer(),
context_length: Optional[int] = None,
num_layers: int = 2,
num_cells: int = 40,
cell_type: str = "lstm",
dropout_rate: float = 0.1,
use_feat_dynamic_real: bool = False,
use_feat_static_cat: bool = False,
cardinality: Optional[List[int]] = None,
embedding_dimension: int = 20,
distr_output: DistributionOutput = StudentTOutput(),
scaling: bool = True,
lags_seq: Optional[List[int]] = None,
time_features: Optional[List[TimeFeature]] = None,
num_parallel_samples: int = 100,
) -> None:
super().__init__(trainer=trainer)
assert (
prediction_length > 0
), "The value of `prediction_length` should be > 0"
assert (
context_length is None or context_length > 0
), "The value of `context_length` should be > 0"
assert num_layers > 0, "The value of `num_layers` should be > 0"
assert num_cells > 0, "The value of `num_cells` should be > 0"
assert dropout_rate >= 0, "The value of `dropout_rate` should be >= 0"
assert (
cardinality is not None or not use_feat_static_cat
), "You must set `cardinality` if `use_feat_static_cat=True`"
assert cardinality is None or [
c > 0 for c in cardinality
], "Elements of `cardinality` should be > 0"
assert (
embedding_dimension > 0
), "The value of `embedding_dimension` should be > 0"
assert (
num_parallel_samples > 0
), "The value of `num_parallel_samples` should be > 0"
self.freq = freq
self.context_length = (
context_length if context_length is not None else prediction_length
)
self.prediction_length = prediction_length
self.distr_output = distr_output
self.num_layers = num_layers
self.num_cells = num_cells
self.cell_type = cell_type
self.dropout_rate = dropout_rate
self.use_feat_dynamic_real = use_feat_dynamic_real
self.use_feat_static_cat = use_feat_static_cat
self.cardinality = cardinality if use_feat_static_cat else [1]
self.embedding_dimension = embedding_dimension
self.scaling = scaling
self.lags_seq = (
lags_seq
if lags_seq is not None
else get_lags_for_frequency(freq_str=freq)
)
self.time_features = (
time_features
if time_features is not None
else time_features_from_frequency_str(self.freq)
)
self.history_length = self.context_length + max(self.lags_seq)
self.num_parallel_samples = num_parallel_samples
def create_transformation(self) -> Transformation:
remove_field_names = [
FieldName.FEAT_DYNAMIC_CAT,
FieldName.FEAT_STATIC_REAL,
]
if not self.use_feat_dynamic_real:
remove_field_names.append(FieldName.FEAT_DYNAMIC_REAL)
return Chain(
[RemoveFields(field_names=remove_field_names)]
+ (
[SetField(output_field=FieldName.FEAT_STATIC_CAT, value=[0.0])]
if not self.use_feat_static_cat
else []
)
+ [
AsNumpyArray(field=FieldName.FEAT_STATIC_CAT, expected_ndim=1),
AsNumpyArray(
field=FieldName.TARGET,
# in the following line, we add 1 for the time dimension
expected_ndim=1 + len(self.distr_output.event_shape),
),
AddObservedValuesIndicator(
target_field=FieldName.TARGET,
output_field=FieldName.OBSERVED_VALUES,
),
AddTimeFeatures(
start_field=FieldName.START,
target_field=FieldName.TARGET,
output_field=FieldName.FEAT_TIME,
time_features=self.time_features,
pred_length=self.prediction_length,
),
AddAgeFeature(
target_field=FieldName.TARGET,
output_field=FieldName.FEAT_AGE,
pred_length=self.prediction_length,
log_scale=True,
),
VstackFeatures(
output_field=FieldName.FEAT_TIME,
input_fields=[FieldName.FEAT_TIME, FieldName.FEAT_AGE]
+ (
[FieldName.FEAT_DYNAMIC_REAL]
if self.use_feat_dynamic_real
else []
),
),
InstanceSplitter(
target_field=FieldName.TARGET,
is_pad_field=FieldName.IS_PAD,
start_field=FieldName.START,
forecast_start_field=FieldName.FORECAST_START,
train_sampler=ExpectedNumInstanceSampler(num_instances=1),
past_length=self.history_length,
future_length=self.prediction_length,
time_series_fields=[
FieldName.FEAT_TIME,
FieldName.OBSERVED_VALUES,
],
),
]
)
def create_training_network(self) -> DeepARTrainingNetwork:
return DeepARTrainingNetwork(
num_layers=self.num_layers,
num_cells=self.num_cells,
cell_type=self.cell_type,
history_length=self.history_length,
context_length=self.context_length,
prediction_length=self.prediction_length,
distr_output=self.distr_output,
dropout_rate=self.dropout_rate,
cardinality=self.cardinality,
embedding_dimension=self.embedding_dimension,
lags_seq=self.lags_seq,
scaling=self.scaling,
)
def create_predictor(
self, transformation: Transformation, trained_network: HybridBlock
) -> Predictor:
prediction_network = DeepARPredictionNetwork(
num_parallel_samples=self.num_parallel_samples,
num_layers=self.num_layers,
num_cells=self.num_cells,
cell_type=self.cell_type,
history_length=self.history_length,
context_length=self.context_length,
prediction_length=self.prediction_length,
distr_output=self.distr_output,
dropout_rate=self.dropout_rate,
cardinality=self.cardinality,
embedding_dimension=self.embedding_dimension,
lags_seq=self.lags_seq,
scaling=self.scaling,
)
copy_parameters(trained_network, prediction_network)
return RepresentableBlockPredictor(
input_transform=transformation,
prediction_net=prediction_network,
batch_size=self.trainer.batch_size,
freq=self.freq,
prediction_length=self.prediction_length,
ctx=self.trainer.ctx,
)
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