/
premade_lib.py
1817 lines (1609 loc) · 76.6 KB
/
premade_lib.py
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# Copyright 2019 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.
"""Implementation of algorithms required for premade models."""
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
import collections
import copy
import enum
import itertools
from absl import logging
import numpy as np
import six
import tensorflow as tf
# pylint: disable=g-import-not-at-top
# Use Keras 2.
version_fn = getattr(tf.keras, 'version', None)
if version_fn and version_fn().startswith('3.'):
import tf_keras as keras
else:
keras = tf.keras
from . import aggregation_layer
from . import categorical_calibration_layer
from . import configs
from . import kronecker_factored_lattice_layer as kfll
from . import kronecker_factored_lattice_lib as kfl_lib
from . import lattice_layer
from . import lattice_lib
from . import linear_layer
from . import pwl_calibration_layer
from . import rtl_layer
from . import utils
# Layer names used for layers in the premade models.
AGGREGATION_LAYER_NAME = 'tfl_aggregation'
CALIB_LAYER_NAME = 'tfl_calib'
INPUT_LAYER_NAME = 'tfl_input'
KFL_LAYER_NAME = 'tfl_kronecker_factored_lattice'
LATTICE_LAYER_NAME = 'tfl_lattice'
LINEAR_LAYER_NAME = 'tfl_linear'
OUTPUT_LINEAR_COMBINATION_LAYER_NAME = 'tfl_output_linear_combination'
OUTPUT_CALIB_LAYER_NAME = 'tfl_output_calib'
RTL_LAYER_NAME = 'tfl_rtl'
RTL_INPUT_NAME = 'tfl_rtl_input'
# Prefix for passthrough (identity) nodes for shared calibration.
# These nodes pass shared calibrated values to submodels in an ensemble.
CALIB_PASSTHROUGH_NAME = 'tfl_calib_passthrough'
# Prefix for defining feature calibrator regularizers.
_INPUT_CALIB_REGULARIZER_PREFIX = 'calib_'
# Prefix for defining output calibrator regularizers.
_OUTPUT_CALIB_REGULARIZER_PREFIX = 'output_calib_'
# Weight of laplacian in feature importance for the crystal algorithm.
_LAPLACIAN_WEIGHT_IN_IMPORTANCE = 6.0
# Discount amount for repeated co-occurrence of pairs of features in crystals.
_REPEATED_PAIR_DISCOUNT_IN_CRYSTALS_SCORE = 0.5
# Maximum number of swaps for the crystals algorithm.
_MAX_CRYSTALS_SWAPS = 1000
def _input_calibration_regularizers(model_config, feature_config):
"""Returns pwl layer regularizers defined in the model and feature configs."""
regularizer_configs = []
regularizer_configs.extend(feature_config.regularizer_configs or [])
regularizer_configs.extend(model_config.regularizer_configs or [])
return [(r.name.replace(_INPUT_CALIB_REGULARIZER_PREFIX, ''), r.l1, r.l2)
for r in regularizer_configs
if r.name.startswith(_INPUT_CALIB_REGULARIZER_PREFIX)]
def _middle_calibration_regularizers(model_config):
"""Returns pwl layer regularizers defined in the model config."""
regularizer_configs = []
regularizer_configs.extend(model_config.regularizer_configs or [])
return [(r.name.replace(_INPUT_CALIB_REGULARIZER_PREFIX, ''), r.l1, r.l2)
for r in regularizer_configs
if r.name.startswith(_INPUT_CALIB_REGULARIZER_PREFIX)]
def _output_calibration_regularizers(model_config):
"""Returns output calibration regularizers defined in the model config."""
return [(r.name.replace(_OUTPUT_CALIB_REGULARIZER_PREFIX, ''), r.l1, r.l2)
for r in model_config.regularizer_configs or []
if r.name.startswith(_OUTPUT_CALIB_REGULARIZER_PREFIX)]
def _lattice_regularizers(model_config, feature_configs):
"""Returns lattice regularizers defined in the model and feature configs."""
# dict from regularizer name to pair of per feature l1 and l2 amounts.
regularizers_dict = {}
n_dims = len(feature_configs)
for index, feature_config in enumerate(feature_configs):
for regularizer_config in feature_config.regularizer_configs or []:
if not (
regularizer_config.name.startswith(_INPUT_CALIB_REGULARIZER_PREFIX) or
regularizer_config.name.startswith(_OUTPUT_CALIB_REGULARIZER_PREFIX)):
if regularizer_config.name not in regularizers_dict:
regularizers_dict[regularizer_config.name] = ([0.0] * n_dims,
[0.0] * n_dims)
regularizers_dict[
regularizer_config.name][0][index] += regularizer_config.l1
regularizers_dict[
regularizer_config.name][1][index] += regularizer_config.l2
regularizers = [(k,) + v for k, v in regularizers_dict.items()]
for regularizer_config in model_config.regularizer_configs or []:
if not (
regularizer_config.name.startswith(_INPUT_CALIB_REGULARIZER_PREFIX) or
regularizer_config.name.startswith(_OUTPUT_CALIB_REGULARIZER_PREFIX)):
regularizers.append((regularizer_config.name, regularizer_config.l1,
regularizer_config.l2))
return regularizers
class LayerOutputRange(enum.Enum):
"""Enum to indicate the output range based on the input of the next layers."""
MODEL_OUTPUT = 1
INPUT_TO_LATTICE = 2
INPUT_TO_FINAL_CALIBRATION = 3
def _output_range(layer_output_range, model_config, feature_config=None):
"""Returns min/max/init_min/init_max for a given output range."""
if layer_output_range == LayerOutputRange.INPUT_TO_LATTICE:
if feature_config is None:
raise ValueError('Expecting feature config for lattice inputs.')
output_init_min = output_min = 0.0
output_init_max = output_max = feature_config.lattice_size - 1.0
elif layer_output_range == LayerOutputRange.MODEL_OUTPUT:
output_min = model_config.output_min
output_max = model_config.output_max
# Note: due to the multiplicative nature of KroneckerFactoredLattice layers,
# the initialization min/max do not correspond directly to the output
# min/max. Thus we follow the same scheme as the KroneckerFactoredLattice
# lattice layer to properly initialize the kernel and scale such that
# the output does in fact respect the requested bounds.
if ((isinstance(model_config, configs.CalibratedLatticeEnsembleConfig) or
isinstance(model_config, configs.CalibratedLatticeConfig)) and
model_config.parameterization == 'kronecker_factored'):
output_init_min, output_init_max = kfl_lib.default_init_params(
output_min, output_max)
else:
output_init_min = np.min(model_config.output_initialization)
output_init_max = np.max(model_config.output_initialization)
elif layer_output_range == LayerOutputRange.INPUT_TO_FINAL_CALIBRATION:
output_init_min = output_min = 0.0
output_init_max = output_max = 1.0
else:
raise ValueError('Unsupported layer output range.')
return output_min, output_max, output_init_min, output_init_max
def build_input_layer(feature_configs, dtype, ragged=False):
"""Creates a mapping from feature name to `keras.Input`.
Args:
feature_configs: A list of `tfl.configs.FeatureConfig` instances that
specify configurations for each feature.
dtype: dtype
ragged: If the inputs are ragged tensors.
Returns:
Mapping from feature name to `keras.Input` for the inputs specified by
`feature_configs`.
"""
input_layer = {}
shape = (None,) if ragged else (1,)
for feature_config in feature_configs:
layer_name = '{}_{}'.format(INPUT_LAYER_NAME, feature_config.name)
if feature_config.num_buckets:
input_layer[feature_config.name] = keras.Input(
shape=shape, ragged=ragged, dtype=tf.int32, name=layer_name)
else:
input_layer[feature_config.name] = keras.Input(
shape=shape, ragged=ragged, dtype=dtype, name=layer_name)
return input_layer
def build_multi_unit_calibration_layers(calibration_input_layer,
calibration_output_units, model_config,
layer_output_range,
output_single_tensor, dtype):
"""Creates a mapping from feature names to calibration outputs.
Args:
calibration_input_layer: A mapping from feature name to `keras.Input`.
calibration_output_units: A mapping from feature name to units.
model_config: Model configuration object describing model architecture.
Should be one of the model configs in `tfl.configs`.
layer_output_range: A `tfl.premade_lib.LayerOutputRange` enum.
output_single_tensor: If output for each feature should be a single tensor.
dtype: dtype
Returns:
A mapping from feature name to calibration output Tensors.
"""
calibration_output = {}
for feature_name, units in calibration_output_units.items():
if units == 0:
raise ValueError(
'Feature {} is not used. Calibration output units is 0.'.format(
feature_name))
feature_config = model_config.feature_config_by_name(feature_name)
calibration_input = calibration_input_layer[feature_name]
layer_name = '{}_{}'.format(CALIB_LAYER_NAME, feature_name)
(output_min, output_max, output_init_min,
output_init_max) = _output_range(layer_output_range, model_config,
feature_config)
if feature_config.num_buckets:
kernel_initializer = keras.initializers.RandomUniform(
output_init_min, output_init_max)
calibrated = (
categorical_calibration_layer.CategoricalCalibration(
num_buckets=feature_config.num_buckets,
units=units,
output_min=output_min,
output_max=output_max,
kernel_initializer=kernel_initializer,
monotonicities=feature_config.monotonicity if isinstance(
feature_config.monotonicity, list) else None,
default_input_value=feature_config.default_value,
split_outputs=(units > 1 and not output_single_tensor),
dtype=dtype,
name=layer_name)(calibration_input))
else:
kernel_regularizer = _input_calibration_regularizers(
model_config, feature_config)
monotonicity = feature_config.monotonicity
if (utils.canonicalize_monotonicity(monotonicity) == 0 and
feature_config.pwl_calibration_always_monotonic):
monotonicity = 1
kernel_initializer = pwl_calibration_layer.UniformOutputInitializer(
output_min=output_init_min,
output_max=output_init_max,
monotonicity=monotonicity,
keypoints=feature_config.pwl_calibration_input_keypoints)
calibrated = (
pwl_calibration_layer.PWLCalibration(
units=units,
input_keypoints=feature_config.pwl_calibration_input_keypoints,
output_min=output_min,
output_max=output_max,
clamp_min=feature_config.pwl_calibration_clamp_min,
clamp_max=feature_config.pwl_calibration_clamp_max,
missing_input_value=feature_config.default_value,
impute_missing=(feature_config.default_value is not None),
kernel_initializer=kernel_initializer,
kernel_regularizer=kernel_regularizer,
monotonicity=monotonicity,
convexity=feature_config.pwl_calibration_convexity,
split_outputs=(units > 1 and not output_single_tensor),
input_keypoints_type=feature_config
.pwl_calibration_input_keypoints_type,
dtype=dtype,
name=layer_name)(calibration_input))
if output_single_tensor:
calibration_output[feature_name] = calibrated
elif units == 1:
calibration_output[feature_name] = [calibrated]
else:
# calibrated will have already been split in this case.
calibration_output[feature_name] = calibrated
return calibration_output
def build_calibration_layers(calibration_input_layer, model_config,
layer_output_range, submodels,
separate_calibrators, dtype):
"""Creates a calibration layer for `submodels` as list of list of features.
Args:
calibration_input_layer: A mapping from feature name to `keras.Input`.
model_config: Model configuration object describing model architecture.
Should be one of the model configs in `tfl.configs`.
layer_output_range: A `tfl.premade_lib.LayerOutputRange` enum.
submodels: A list of list of feature names.
separate_calibrators: If features should be separately calibrated for each
lattice in an ensemble.
dtype: dtype
Returns:
A list of list of Tensors representing a calibration layer for `submodels`.
"""
# Create a list of (feature_name, calibration_output_idx) pairs for each
# submodel. When using shared calibration, all submodels will have
# calibration_output_idx = 0.
submodels_input_features = []
calibration_last_index = collections.defaultdict(int)
for submodel in submodels:
submodel_input_features = []
submodels_input_features.append(submodel_input_features)
for feature_name in submodel:
submodel_input_features.append(
(feature_name, calibration_last_index[feature_name]))
if separate_calibrators:
calibration_last_index[feature_name] += 1
# This is to account for shared calibration.
calibration_output_units = {
name: max(index, 1) for name, index in calibration_last_index.items()
}
calibration_output = build_multi_unit_calibration_layers(
calibration_input_layer=calibration_input_layer,
calibration_output_units=calibration_output_units,
model_config=model_config,
layer_output_range=layer_output_range,
output_single_tensor=False,
dtype=dtype)
# Create passthrough nodes for each submodel input so that we can recover
# the model structure for plotting and analysis.
# {CALIB_PASSTHROUGH_NAME}_{feature_name}_
# {calibration_output_idx}_{submodel_idx}_{submodel_input_idx}
submodels_inputs = []
for submodel_idx, submodel_input_features in enumerate(
submodels_input_features):
submodel_inputs = []
submodels_inputs.append(submodel_inputs)
for (submodel_input_idx,
(feature_name,
calibration_output_idx)) in enumerate(submodel_input_features):
passthrough_name = '{}_{}_{}_{}_{}'.format(CALIB_PASSTHROUGH_NAME,
feature_name,
calibration_output_idx,
submodel_idx,
submodel_input_idx)
submodel_inputs.append(
tf.identity(
calibration_output[feature_name][calibration_output_idx],
name=passthrough_name))
return submodels_inputs
def build_aggregation_layer(aggregation_input_layer, model_config,
calibrated_lattice_models, layer_output_range,
submodel_index, dtype):
"""Creates an aggregation layer using the given calibrated lattice models.
Args:
aggregation_input_layer: A list or a mapping from feature name to
`keras.Input`, in the order or format expected by
`calibrated_lattice_models`.
model_config: Model configuration object describing model architecture.
Should be one of the model configs in `tfl.configs`.
calibrated_lattice_models: A list of calibrated lattice models of size
model_config.middle_diemnsion, where each calbirated lattice model
instance is constructed using the same model configuration object.
layer_output_range: A `tfl.premade_lib.LayerOutputRange` enum.
submodel_index: Corresponding index into submodels.
dtype: dtype
Returns:
A list of list of Tensors representing a calibration layer for `submodels`.
"""
(output_min, output_max, output_init_min,
output_init_max) = _output_range(layer_output_range, model_config)
lattice_sizes = [model_config.middle_lattice_size
] * model_config.middle_dimension
lattice_monotonicities = [1] * model_config.middle_dimension
# Create the aggergated embeddings to pass to the middle lattice.
lattice_inputs = []
for i in range(model_config.middle_dimension):
agg_layer_name = '{}_{}'.format(AGGREGATION_LAYER_NAME, i)
agg_output = aggregation_layer.Aggregation(
calibrated_lattice_models[i], name=agg_layer_name)(
aggregation_input_layer)
agg_output = keras.layers.Reshape((1,))(agg_output)
if model_config.middle_calibration:
agg_output = pwl_calibration_layer.PWLCalibration(
input_keypoints=np.linspace(
-1.0,
1.0,
num=model_config.middle_calibration_num_keypoints,
dtype=np.float32),
output_min=0.0,
output_max=lattice_sizes[i] - 1.0,
monotonicity=utils.canonicalize_monotonicity(
model_config.middle_monotonicity),
kernel_regularizer=_middle_calibration_regularizers(model_config),
input_keypoints_type=model_config
.middle_calibration_input_keypoints_type,
dtype=dtype,
)(
agg_output)
agg_output = keras.layers.Reshape((1,))(agg_output)
lattice_inputs.append(agg_output)
# We use random monotonic initialization here to break the symmetry that we
# would otherwise have between middle lattices. Since we use the same
# CalibratedLattice for each of the middle dimensions, if we do not randomly
# initialize the middle lattice we will have the same gradient flow back for
# each middle dimension, thus acting the same as if there was only one middle
# dimension.
kernel_initializer = lattice_layer.RandomMonotonicInitializer(
lattice_sizes=lattice_sizes,
output_min=output_init_min,
output_max=output_init_max)
lattice_layer_name = '{}_{}'.format(LATTICE_LAYER_NAME, submodel_index)
return lattice_layer.Lattice(
lattice_sizes=lattice_sizes,
monotonicities=lattice_monotonicities,
output_min=output_min,
output_max=output_max,
clip_inputs=False,
interpolation=model_config.middle_lattice_interpolation,
kernel_initializer=kernel_initializer,
dtype=dtype,
name=lattice_layer_name,
)(
lattice_inputs)
def _monotonicities_from_feature_configs(feature_configs):
"""Returns list of monotonicities defined in the given feature_configs."""
monotonicities = []
for feature_config in feature_configs:
if not feature_config.monotonicity:
monotonicities.append(0)
elif (isinstance(feature_config.monotonicity, six.string_types) and
feature_config.monotonicity.lower() == 'none'):
monotonicities.append(0)
else:
monotonicities.append(1)
return monotonicities
def _dominance_constraints_from_feature_configs(feature_configs):
"""Returns list of dominance constraints in the given feature_configs."""
feature_names = [feature_config.name for feature_config in feature_configs]
monotonic_dominances = []
for dominant_idx, dominant_feature_config in enumerate(feature_configs):
for dominance_config in dominant_feature_config.dominates or []:
if dominance_config.feature_name in feature_names:
weak_idx = feature_names.index(dominance_config.feature_name)
if dominance_config.dominance_type == 'monotonic':
monotonic_dominances.append((dominant_idx, weak_idx))
else:
raise ValueError('Unrecognized dominance type: {}'.format(
dominance_config.dominance_type))
return monotonic_dominances
def _canonical_feature_names(model_config, feature_names=None):
if feature_names is not None:
return feature_names
if model_config.feature_configs is None:
raise ValueError(
'Feature configs must be specified if feature names are not provided.')
return [
feature_config.name for feature_config in model_config.feature_configs
]
def build_linear_layer(linear_input, feature_configs, model_config,
weighted_average, submodel_index, dtype):
"""Creates a `tfl.layers.Linear` layer initialized to be an average.
Args:
linear_input: Input to the linear layer.
feature_configs: A list of `tfl.configs.FeatureConfig` instances that
specify configurations for each feature.
model_config: Model configuration object describing model architecture.
Should be one of the model configs in `tfl.configs`.
weighted_average: If the linear coefficients should be positive and sum up
to one.
submodel_index: Corresponding index into submodels.
dtype: dtype
Returns:
A `tfl.layers.Linear` instance.
"""
layer_name = '{}_{}'.format(LINEAR_LAYER_NAME, submodel_index)
linear_input = keras.layers.Concatenate(axis=1)(linear_input)
num_input_dims = len(feature_configs)
kernel_initializer = keras.initializers.Constant([1.0 / num_input_dims] *
num_input_dims)
bias_initializer = keras.initializers.Constant(0)
if weighted_average:
# Linear coefficients should be possitive and sum up to one.
linear_monotonicities = [1] * num_input_dims
normalization_order = 1
use_bias = False
else:
linear_monotonicities = _monotonicities_from_feature_configs(
feature_configs)
normalization_order = None
use_bias = model_config.use_bias
monotonic_dominances = _dominance_constraints_from_feature_configs(
feature_configs)
return linear_layer.Linear(
num_input_dims=num_input_dims,
monotonicities=linear_monotonicities,
monotonic_dominances=monotonic_dominances,
use_bias=use_bias,
normalization_order=normalization_order,
kernel_initializer=kernel_initializer,
bias_initializer=bias_initializer,
dtype=dtype,
name=layer_name)(
linear_input)
def build_lattice_layer(lattice_input, feature_configs, model_config,
layer_output_range, submodel_index, is_inside_ensemble,
dtype):
"""Creates a `tfl.layers.Lattice` layer.
Args:
lattice_input: Input to the lattice layer.
feature_configs: A list of `tfl.configs.FeatureConfig` instances that
specify configurations for each feature.
model_config: Model configuration object describing model architecture.
Should be one of the model configs in `tfl.configs`.
layer_output_range: A `tfl.premade_lib.LayerOutputRange` enum.
submodel_index: Corresponding index into submodels.
is_inside_ensemble: If this layer is inside an ensemble.
dtype: dtype
Returns:
A `tfl.layers.Lattice` instance if `model_config.parameterization` is set to
`'all_vertices'` or a `tfl.layers.KroneckerFactoredLattice` instance if
set to `'kronecker_factored'`.
Raises:
ValueError: If `model_config.parameterization` is not one of
`'all_vertices'` or `'kronecker_factored'`.
"""
layer_name = '{}_{}'.format(LATTICE_LAYER_NAME, submodel_index)
(output_min, output_max, output_init_min,
output_init_max) = _output_range(layer_output_range, model_config)
feature_names = [feature_config.name for feature_config in feature_configs]
lattice_sizes = [
feature_config.lattice_size for feature_config in feature_configs
]
lattice_monotonicities = _monotonicities_from_feature_configs(feature_configs)
lattice_unimodalities = [
feature_config.unimodality for feature_config in feature_configs
]
lattice_regularizers = _lattice_regularizers(model_config,
feature_configs) or None
# Construct trust constraints within this lattice.
edgeworth_trusts = []
trapezoid_trusts = []
for conditional_idx, conditional_feature_config in enumerate(feature_configs):
for trust_config in conditional_feature_config.reflects_trust_in or []:
if trust_config.feature_name in feature_names:
main_idx = feature_names.index(trust_config.feature_name)
if trust_config.trust_type == 'edgeworth':
edgeworth_trusts.append(
(main_idx, conditional_idx, trust_config.direction))
elif trust_config.trust_type == 'trapezoid':
trapezoid_trusts.append(
(main_idx, conditional_idx, trust_config.direction))
else:
raise ValueError('Unrecognized trust type: {}'.format(
trust_config.trust_type))
elif is_inside_ensemble and trust_config.trust_type == 'trapezoid':
logging.warning(
'A "main" feature (%s) for a trapezoid trust constraint is not '
'present in a lattice that includes the "conditional" feature '
'(%s). In an ensemble model, this can result in constraint '
'violations. Consider manually setting the ensemble structure if '
'this constraint needs to be satisfied.', trust_config.feature_name,
conditional_feature_config.name)
monotonic_dominances = _dominance_constraints_from_feature_configs(
feature_configs)
if model_config.parameterization == 'all_vertices':
layer_name = '{}_{}'.format(LATTICE_LAYER_NAME, submodel_index)
kernel_initializer = lattice_layer.LinearInitializer(
lattice_sizes=lattice_sizes,
monotonicities=lattice_monotonicities,
unimodalities=lattice_unimodalities,
output_min=output_init_min,
output_max=output_init_max)
return lattice_layer.Lattice(
lattice_sizes=lattice_sizes,
monotonicities=lattice_monotonicities,
unimodalities=lattice_unimodalities,
edgeworth_trusts=edgeworth_trusts,
trapezoid_trusts=trapezoid_trusts,
monotonic_dominances=monotonic_dominances,
output_min=output_min,
output_max=output_max,
clip_inputs=False,
interpolation=model_config.interpolation,
kernel_regularizer=lattice_regularizers,
kernel_initializer=kernel_initializer,
dtype=dtype,
name=layer_name)(
lattice_input)
elif model_config.parameterization == 'kronecker_factored':
layer_name = '{}_{}'.format(KFL_LAYER_NAME, submodel_index)
kernel_initializer = kfll.KFLRandomMonotonicInitializer(
monotonicities=lattice_monotonicities,
init_min=output_init_min,
init_max=output_init_max,
seed=model_config.random_seed)
scale_initializer = kfll.ScaleInitializer(
output_min=output_min, output_max=output_max)
return kfll.KroneckerFactoredLattice(
lattice_sizes=lattice_sizes[0],
num_terms=model_config.num_terms,
monotonicities=lattice_monotonicities,
output_min=output_min,
output_max=output_max,
clip_inputs=False,
kernel_initializer=kernel_initializer,
scale_initializer=scale_initializer,
dtype=dtype,
name=layer_name)(
lattice_input)
else:
raise ValueError('Unknown type of parameterization: {}'.format(
model_config.parameterization))
def build_lattice_ensemble_layer(submodels_inputs, model_config, dtype):
"""Creates an ensemble of `tfl.layers.Lattice` layers.
Args:
submodels_inputs: List of inputs to each of the lattice layers in the
ensemble. The order corresponds to the elements of model_config.lattices.
model_config: Model configuration object describing model architecture.
Should be one of the model configs in `tfl.configs`.
dtype: dtype
Returns:
A list of `tfl.layers.Lattice` instances.
"""
lattice_outputs = []
for submodel_index, (lattice_feature_names, lattice_input) in enumerate(
zip(model_config.lattices, submodels_inputs)):
lattice_feature_configs = [
model_config.feature_config_by_name(feature_name)
for feature_name in lattice_feature_names
]
lattice_layer_output_range = (
LayerOutputRange.INPUT_TO_FINAL_CALIBRATION
if model_config.output_calibration else LayerOutputRange.MODEL_OUTPUT)
lattice_outputs.append(
build_lattice_layer(
lattice_input=lattice_input,
feature_configs=lattice_feature_configs,
model_config=model_config,
layer_output_range=lattice_layer_output_range,
submodel_index=submodel_index,
is_inside_ensemble=True,
dtype=dtype))
return lattice_outputs
def build_rtl_layer(calibration_outputs, model_config, submodel_index,
average_outputs, dtype):
"""Creates a `tfl.layers.RTL` layer.
This function expects that all features defined in
model_config.feature_configs are used and present in calibration_outputs.
Args:
calibration_outputs: A mapping from feature name to calibration output.
model_config: Model configuration object describing model architecture.
Should be one of the model configs in `tfl.configs`.
submodel_index: Corresponding index into submodels.
average_outputs: Whether to average the outputs of this layer.
dtype: dtype
Returns:
A `tfl.layers.RTL` instance.
Raises:
ValueError: If `model_config.parameterization` is not one of
`'all_vertices'` or `'kronecker_factored'`.
"""
layer_name = '{}_{}'.format(RTL_LAYER_NAME, submodel_index)
rtl_layer_output_range = (
LayerOutputRange.INPUT_TO_FINAL_CALIBRATION
if model_config.output_calibration else LayerOutputRange.MODEL_OUTPUT)
(output_min, output_max, output_init_min,
output_init_max) = _output_range(rtl_layer_output_range, model_config)
lattice_regularizers = _lattice_regularizers(
model_config, model_config.feature_configs) or None
rtl_inputs = collections.defaultdict(list)
for feature_config in model_config.feature_configs:
passthrough_name = '{}_{}'.format(RTL_INPUT_NAME, feature_config.name)
calibration_output = tf.identity(
calibration_outputs[feature_config.name], name=passthrough_name)
if feature_config.monotonicity in [1, -1, 'increasing', 'decreasing']:
rtl_inputs['increasing'].append(calibration_output)
else:
rtl_inputs['unconstrained'].append(calibration_output)
lattice_size = model_config.feature_configs[0].lattice_size
if model_config.parameterization == 'all_vertices':
kernel_initializer = 'random_monotonic_initializer'
elif model_config.parameterization == 'kronecker_factored':
kernel_initializer = 'kfl_random_monotonic_initializer'
else:
raise ValueError('Unknown type of parameterization: {}'.format(
model_config.parameterization))
return rtl_layer.RTL(
num_lattices=model_config.num_lattices,
lattice_rank=model_config.lattice_rank,
lattice_size=lattice_size,
output_min=output_min,
output_max=output_max,
init_min=output_init_min,
init_max=output_init_max,
random_seed=model_config.random_seed,
clip_inputs=False,
interpolation=model_config.interpolation,
parameterization=model_config.parameterization,
num_terms=model_config.num_terms,
kernel_regularizer=lattice_regularizers,
kernel_initializer=kernel_initializer,
average_outputs=average_outputs,
dtype=dtype,
name=layer_name)(
rtl_inputs)
def build_calibrated_lattice_ensemble_layer(calibration_input_layer,
model_config, average_outputs,
dtype):
"""Creates a calibration layer followed by a lattice ensemble layer.
Args:
calibration_input_layer: A mapping from feature name to `keras.Input`.
model_config: Model configuration object describing model architecture.
Should be one of the model configs in `tfl.configs`.
average_outputs: Whether to average the outputs of this layer.
dtype: dtype
Returns:
A `tfl.layers.RTL` instance if model_config.lattices is 'rtl_layer.
Otherwise a list of `tfl.layers.Lattice` instances.
"""
if model_config.lattices == 'rtl_layer':
num_features = len(model_config.feature_configs)
units = [1] * num_features
if model_config.separate_calibrators:
num_inputs = model_config.num_lattices * model_config.lattice_rank
# We divide the number of inputs semi-evenly by the number of features.
# TODO: support setting number of calibration units.
for i in range(num_features):
units[i] = ((i + 1) * num_inputs // num_features -
i * num_inputs // num_features)
calibration_output_units = {
feature_config.name: units[i]
for i, feature_config in enumerate(model_config.feature_configs)
}
calibration_outputs = build_multi_unit_calibration_layers(
calibration_input_layer=calibration_input_layer,
calibration_output_units=calibration_output_units,
model_config=model_config,
layer_output_range=LayerOutputRange.INPUT_TO_LATTICE,
output_single_tensor=True,
dtype=dtype)
lattice_outputs = build_rtl_layer(
calibration_outputs=calibration_outputs,
model_config=model_config,
submodel_index=0,
average_outputs=average_outputs,
dtype=dtype)
else:
submodels_inputs = build_calibration_layers(
calibration_input_layer=calibration_input_layer,
model_config=model_config,
layer_output_range=LayerOutputRange.INPUT_TO_LATTICE,
submodels=model_config.lattices,
separate_calibrators=model_config.separate_calibrators,
dtype=dtype)
lattice_outputs = build_lattice_ensemble_layer(
submodels_inputs=submodels_inputs,
model_config=model_config,
dtype=dtype)
if average_outputs:
lattice_outputs = keras.layers.Average()(lattice_outputs)
return lattice_outputs
def build_linear_combination_layer(ensemble_outputs, model_config, dtype):
"""Creates a `tfl.layers.Linear` layer initialized to be an average.
Args:
ensemble_outputs: Ensemble outputs to be linearly combined.
model_config: Model configuration object describing model architecture.
Should be one of the model configs in `tfl.configs`.
dtype: dtype
Returns:
A `tfl.layers.Linear` instance.
"""
if isinstance(ensemble_outputs, list):
num_input_dims = len(ensemble_outputs)
linear_input = keras.layers.Concatenate(axis=1)(ensemble_outputs)
else:
num_input_dims = int(ensemble_outputs.shape[1])
linear_input = ensemble_outputs
kernel_initializer = keras.initializers.Constant(1.0 / num_input_dims)
bias_initializer = keras.initializers.Constant(0)
if (not model_config.output_calibration and
model_config.output_min is None and model_config.output_max is None):
normalization_order = None
else:
# We need to use weighted average to keep the output range.
normalization_order = 1
# Bias term cannot be used when this layer should have bounded output.
if model_config.use_bias:
raise ValueError('Cannot use a bias term in linear combination with '
'output bounds or output calibration')
return linear_layer.Linear(
num_input_dims=num_input_dims,
monotonicities=['increasing'] * num_input_dims,
normalization_order=normalization_order,
use_bias=model_config.use_bias,
kernel_initializer=kernel_initializer,
bias_initializer=bias_initializer,
dtype=dtype,
name=OUTPUT_LINEAR_COMBINATION_LAYER_NAME)(
linear_input)
def build_output_calibration_layer(output_calibration_input, model_config,
dtype):
"""Creates a monotonic output calibration layer with inputs range [0, 1].
Args:
output_calibration_input: Input to the output calibration layer.
model_config: Model configuration object describing model architecture.
Should be one of the model configs in `tfl.configs`.
dtype: dtype
Returns:
A `tfl.layers.PWLCalibration` instance.
"""
# kernel format: bias followed by diffs between consecutive keypoint outputs.
kernel_init_values = np.ediff1d(
model_config.output_initialization,
to_begin=model_config.output_initialization[0])
input_keypoints = np.linspace(0.0, 1.0, num=len(kernel_init_values))
kernel_initializer = keras.initializers.Constant(kernel_init_values)
kernel_regularizer = _output_calibration_regularizers(model_config)
return pwl_calibration_layer.PWLCalibration(
input_keypoints=input_keypoints,
output_min=model_config.output_min,
output_max=model_config.output_max,
kernel_initializer=kernel_initializer,
kernel_regularizer=kernel_regularizer,
monotonicity=1,
input_keypoints_type=model_config.output_calibration_input_keypoints_type,
dtype=dtype,
name=OUTPUT_CALIB_LAYER_NAME)(
output_calibration_input)
def set_categorical_monotonicities(feature_configs):
"""Maps categorical monotonicities to indices based on specified vocab list.
Args:
feature_configs: A list of `tfl.configs.FeatureConfig` objects.
"""
if not isinstance(feature_configs, list) or any(
not isinstance(fc, configs.FeatureConfig) for fc in feature_configs):
raise ValueError(
'feature_configs must be a list of tfl.configs.FeatureConfig objects: '
'{}'.format(feature_configs))
for feature_config in feature_configs:
if feature_config.num_buckets and isinstance(feature_config.monotonicity,
list):
# Make sure the vocabulary list exists. If not, assume user has already
# properly set monotonicity as proper indices for this calibrator.
if not feature_config.vocabulary_list:
continue
if not all(
isinstance(m, (list, tuple)) and len(m) == 2
for m in feature_config.monotonicity):
raise ValueError(
'Monotonicities should be a list of pairs (list/tuples): {}'.format(
feature_config.monotonicity))
indexed_monotonicities = []
index_map = {
category: index
for (index, category) in enumerate(feature_config.vocabulary_list)
}
if feature_config.default_value is not None:
index_map[feature_config.default_value] = feature_config.num_buckets - 1
for left, right in feature_config.monotonicity:
for category in [left, right]:
if category not in index_map:
raise ValueError(
'Category `{}` not found in vocabulary list for feature `{}`'
.format(category, feature_config.name))
indexed_monotonicities.append((index_map[left], index_map[right]))
feature_config.monotonicity = indexed_monotonicities
def set_random_lattice_ensemble(model_config, feature_names=None):
"""Sets random lattice ensemble in the given model_config.
Args:
model_config: Model configuration object describing model architecture.
Should be one of the model configs in `tfl.configs`.
feature_names: A list of feature names. If not provided, feature names will
be extracted from the feature configs contained in the model_config.
"""
if not isinstance(model_config, configs.CalibratedLatticeEnsembleConfig):
raise ValueError(
'model_config must be a tfl.configs.CalibratedLatticeEnsembleConfig: {}'
.format(type(model_config)))
if model_config.lattices != 'random':
raise ValueError('model_config.lattices must be set to \'random\'.')
feature_names = _canonical_feature_names(model_config, feature_names)
# Start by using each feature once.
np.random.seed(model_config.random_seed)
model_config.lattices = [[] for _ in range(model_config.num_lattices)]
for feature_name in feature_names:
non_full_indices = [
i for (i, lattice) in enumerate(model_config.lattices)
if len(lattice) < model_config.lattice_rank
]
model_config.lattices[np.random.choice(non_full_indices)].append(
feature_name)
# Fill up lattices avoiding repeated features.
for lattice in model_config.lattices:
feature_names_not_in_lattice = [
feature_name for feature_name in feature_names
if feature_name not in lattice
]
remaining_size = model_config.lattice_rank - len(lattice)
lattice.extend(
np.random.choice(
feature_names_not_in_lattice, size=remaining_size, replace=False))
def _add_pair_to_ensemble(lattices, lattice_rank, i, j):
"""Adds pair (i, j) to the ensemble heuristically."""
# First check if (i, j) pair is already present in a lattice.
for lattice in lattices:
if i in lattice and j in lattice:
return
# Try adding to a lattice that already has either i or j.
for lattice in lattices:
if len(lattice) < lattice_rank:
if i in lattice:
lattice.add(j)
return
if j in lattice:
lattice.add(i)
return