如何定义深层神经网络estimators
2018-09-28 17:25 更新
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""深层神经网络估计器""
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
import six
from tensorflow.python.estimator import estimator
from tensorflow.python.estimator import model_fn
from tensorflow.python.estimator.canned import head as head_lib
from tensorflow.python.estimator.canned import optimizers
from tensorflow.python.feature_column import feature_column as feature_column_lib
from tensorflow.python.layers import core as core_layers
from tensorflow.python.ops import init_ops
from tensorflow.python.ops import nn
from tensorflow.python.ops import partitioned_variables
from tensorflow.python.ops import variable_scope
from tensorflow.python.summary import summary
from tensorflow.python.training import training_util
# The default learning rate of 0.05 is a historical artifact of the initial
# implementation, but seems a reasonable choice.
_LEARNING_RATE = 0.05
def _add_hidden_layer_summary(value, tag):
summary.scalar('%s/fraction_of_zero_values' % tag, nn.zero_fraction(value))
summary.histogram('%s/activation' % tag, value)
def _dnn_model_fn(
features, labels, mode, head, hidden_units, feature_columns,
optimizer='Adagrad', activation_fn=nn.relu, dropout=None,
input_layer_partitioner=None, config=None):
"""Deep Neural Net model_fn.
Args:
features: dict of `Tensor`.
labels: `Tensor` of shape [batch_size, 1] or [batch_size] labels of
dtype `int32` or `int64` in the range `[0, n_classes)`.
mode: Defines whether this is training, evaluation or prediction.
See `ModeKeys`.
head: A `head_lib._Head` instance.
hidden_units: Iterable of integer number of hidden units per layer.
feature_columns: Iterable of `feature_column._FeatureColumn` model inputs.
optimizer: String, `tf.Optimizer` object, or callable that creates the
optimizer to use for training. If not specified, will use the Adagrad
optimizer with a default learning rate of 0.05.
activation_fn: Activation function applied to each layer.
dropout: When not `None`, the probability we will drop out a given
coordinate.
input_layer_partitioner: Partitioner for input layer. Defaults
to `min_max_variable_partitioner` with `min_slice_size` 64 << 20.
config: `RunConfig` object to configure the runtime settings.
Returns:
predictions: A dict of `Tensor` objects.
loss: A scalar containing the loss of the step.
train_op: The op for training.
Raises:
ValueError: If features has the wrong type.
"""
if not isinstance(features, dict):
raise ValueError('features should be a dictionary of `Tensor`s. '
'Given type: {}'.format(type(features)))
optimizer = optimizers.get_optimizer_instance(
optimizer, learning_rate=_LEARNING_RATE)
num_ps_replicas = config.num_ps_replicas if config else 0
partitioner = partitioned_variables.min_max_variable_partitioner(
max_partitions=num_ps_replicas)
with variable_scope.variable_scope(
'dnn',
values=tuple(six.itervalues(features)),
partitioner=partitioner):
input_layer_partitioner = input_layer_partitioner or (
partitioned_variables.min_max_variable_partitioner(
max_partitions=num_ps_replicas,
min_slice_size=64 << 20))
with variable_scope.variable_scope(
'input_from_feature_columns',
values=tuple(six.itervalues(features)),
partitioner=input_layer_partitioner):
net = feature_column_lib.input_layer(
features=features,
feature_columns=feature_columns)
for layer_id, num_hidden_units in enumerate(hidden_units):
with variable_scope.variable_scope(
'hiddenlayer_%d' % layer_id,
values=(net,)) as hidden_layer_scope:
net = core_layers.dense(
net,
units=num_hidden_units,
activation=activation_fn,
kernel_initializer=init_ops.glorot_uniform_initializer(),
name=hidden_layer_scope)
if dropout is not None and mode == model_fn.ModeKeys.TRAIN:
net = core_layers.dropout(net, rate=dropout, training=True)
_add_hidden_layer_summary(net, hidden_layer_scope.name)
with variable_scope.variable_scope(
'logits',
values=(net,)) as logits_scope:
logits = core_layers.dense(
net,
units=head.logits_dimension,
activation=None,
kernel_initializer=init_ops.glorot_uniform_initializer(),
name=logits_scope)
_add_hidden_layer_summary(logits, logits_scope.name)
def _train_op_fn(loss):
"""Returns the op to optimize the loss."""
return optimizer.minimize(
loss,
global_step=training_util.get_global_step())
return head.create_estimator_spec(
features=features,
mode=mode,
labels=labels,
train_op_fn=_train_op_fn,
logits=logits)
class DNNClassifier(estimator.Estimator):
"""A classifier for TensorFlow DNN models.
Example:
```python
sparse_feature_a = sparse_column_with_hash_bucket(...)
sparse_feature_b = sparse_column_with_hash_bucket(...)
sparse_feature_a_emb = embedding_column(sparse_id_column=sparse_feature_a,
...)
sparse_feature_b_emb = embedding_column(sparse_id_column=sparse_feature_b,
...)
estimator = DNNClassifier(
feature_columns=[sparse_feature_a_emb, sparse_feature_b_emb],
hidden_units=[1024, 512, 256])
# Or estimator using the ProximalAdagradOptimizer optimizer with
# regularization.
estimator = DNNClassifier(
feature_columns=[sparse_feature_a_emb, sparse_feature_b_emb],
hidden_units=[1024, 512, 256],
optimizer=tf.train.ProximalAdagradOptimizer(
learning_rate=0.1,
l1_regularization_strength=0.001
))
# Input builders
def input_fn_train: # returns x, y
pass
estimator.train(input_fn=input_fn_train, steps=100)
def input_fn_eval: # returns x, y
pass
metrics = estimator.evaluate(input_fn=input_fn_eval, steps=10)
def input_fn_predict: # returns x, None
pass
predictions = estimator.predict(input_fn=input_fn_predict)
```
Input of `train` and `evaluate` should have following features,
otherwise there will be a `KeyError`:
* if `weight_column` is not `None`, a feature with
`key=weight_column` whose value is a `Tensor`.
* for each `column` in `feature_columns`:
- if `column` is a `_CategoricalColumn`, a feature with `key=column.name`
whose `value` is a `SparseTensor`.
- if `column` is a `_WeightedCategoricalColumn`, two features: the first
with `key` the id column name, the second with `key` the weight column
name. Both features' `value` must be a `SparseTensor`.
- if `column` is a `_DenseColumn`, a feature with `key=column.name`
whose `value` is a `Tensor`.
Loss is calculated by using softmax cross entropy.
"""
def __init__(self,
hidden_units,
feature_columns,
model_dir=None,
n_classes=2,
weight_column=None,
label_vocabulary=None,
optimizer='Adagrad',
activation_fn=nn.relu,
dropout=None,
input_layer_partitioner=None,
config=None):
"""Initializes a `DNNClassifier` instance.
Args:
hidden_units: Iterable of number hidden units per layer. All layers are
fully connected. Ex. `[64, 32]` means first layer has 64 nodes and
second one has 32.
feature_columns: An iterable containing all the feature columns used by
the model. All items in the set should be instances of classes derived
from `_FeatureColumn`.
model_dir: Directory to save model parameters, graph and etc. This can
also be used to load checkpoints from the directory into a estimator to
continue training a previously saved model.
n_classes: Number of label classes. Defaults to 2, namely binary
classification. Must be > 1.
weight_column: A string or a `_NumericColumn` created by
`tf.feature_column.numeric_column` defining feature column representing
weights. It is used to down weight or boost examples during training. It
will be multiplied by the loss of the example. If it is a string, it is
used as a key to fetch weight tensor from the `features`. If it is a
`_NumericColumn`, raw tensor is fetched by key `weight_column.key`,
then weight_column.normalizer_fn is applied on it to get weight tensor.
label_vocabulary: A list of strings represents possible label values. If
given, labels must be string type and have any value in
`label_vocabulary`. If it is not given, that means labels are
already encoded as integer or float within [0, 1] for `n_classes=2` and
encoded as integer values in {0, 1,..., n_classes-1} for `n_classes`>2 .
Also there will be errors if vocabulary is not provided and labels are
string.
optimizer: An instance of `tf.Optimizer` used to train the model. Defaults
to Adagrad optimizer.
activation_fn: Activation function applied to each layer. If `None`, will
use `tf.nn.relu`.
dropout: When not `None`, the probability we will drop out a given
coordinate.
input_layer_partitioner: Optional. Partitioner for input layer. Defaults
to `min_max_variable_partitioner` with `min_slice_size` 64 << 20.
config: `RunConfig` object to configure the runtime settings.
"""
if n_classes == 2:
head = head_lib._binary_logistic_head_with_sigmoid_cross_entropy_loss( # pylint: disable=protected-access
weight_column=weight_column,
label_vocabulary=label_vocabulary)
else:
head = head_lib._multi_class_head_with_softmax_cross_entropy_loss( # pylint: disable=protected-access
n_classes, weight_column=weight_column,
label_vocabulary=label_vocabulary)
def _model_fn(features, labels, mode, config):
return _dnn_model_fn(
features=features,
labels=labels,
mode=mode,
head=head,
hidden_units=hidden_units,
feature_columns=tuple(feature_columns or []),
optimizer=optimizer,
activation_fn=activation_fn,
dropout=dropout,
input_layer_partitioner=input_layer_partitioner,
config=config)
super(DNNClassifier, self).__init__(
model_fn=_model_fn, model_dir=model_dir, config=config)
class DNNRegressor(estimator.Estimator):
"""A regressor for TensorFlow DNN models.
Example:
```python
sparse_feature_a = sparse_column_with_hash_bucket(...)
sparse_feature_b = sparse_column_with_hash_bucket(...)
sparse_feature_a_emb = embedding_column(sparse_id_column=sparse_feature_a,
...)
sparse_feature_b_emb = embedding_column(sparse_id_column=sparse_feature_b,
...)
estimator = DNNRegressor(
feature_columns=[sparse_feature_a_emb, sparse_feature_b_emb],
hidden_units=[1024, 512, 256])
# Or estimator using the ProximalAdagradOptimizer optimizer with
# regularization.
estimator = DNNRegressor(
feature_columns=[sparse_feature_a_emb, sparse_feature_b_emb],
hidden_units=[1024, 512, 256],
optimizer=tf.train.ProximalAdagradOptimizer(
learning_rate=0.1,
l1_regularization_strength=0.001
))
# Input builders
def input_fn_train: # returns x, y
pass
estimator.train(input_fn=input_fn_train, steps=100)
def input_fn_eval: # returns x, y
pass
metrics = estimator.evaluate(input_fn=input_fn_eval, steps=10)
def input_fn_predict: # returns x, None
pass
predictions = estimator.predict(input_fn=input_fn_predict)
```
Input of `train` and `evaluate` should have following features,
otherwise there will be a `KeyError`:
* if `weight_column` is not `None`, a feature with
`key=weight_column` whose value is a `Tensor`.
* for each `column` in `feature_columns`:
- if `column` is a `_CategoricalColumn`, a feature with `key=column.name`
whose `value` is a `SparseTensor`.
- if `column` is a `_WeightedCategoricalColumn`, two features: the first
with `key` the id column name, the second with `key` the weight column
name. Both features' `value` must be a `SparseTensor`.
- if `column` is a `_DenseColumn`, a feature with `key=column.name`
whose `value` is a `Tensor`.
Loss is calculated by using mean squared error.
"""
def __init__(self,
hidden_units,
feature_columns,
model_dir=None,
label_dimension=1,
weight_column=None,
optimizer='Adagrad',
activation_fn=nn.relu,
dropout=None,
input_layer_partitioner=None,
config=None):
"""Initializes a `DNNRegressor` instance.
Args:
hidden_units: Iterable of number hidden units per layer. All layers are
fully connected. Ex. `[64, 32]` means first layer has 64 nodes and
second one has 32.
feature_columns: An iterable containing all the feature columns used by
the model. All items in the set should be instances of classes derived
from `_FeatureColumn`.
model_dir: Directory to save model parameters, graph and etc. This can
also be used to load checkpoints from the directory into a estimator to
continue training a previously saved model.
label_dimension: Number of regression targets per example. This is the
size of the last dimension of the labels and logits `Tensor` objects
(typically, these have shape `[batch_size, label_dimension]`).
weight_column: A string or a `_NumericColumn` created by
`tf.feature_column.numeric_column` defining feature column representing
weights. It is used to down weight or boost examples during training. It
will be multiplied by the loss of the example. If it is a string, it is
used as a key to fetch weight tensor from the `features`. If it is a
`_NumericColumn`, raw tensor is fetched by key `weight_column.key`,
then weight_column.normalizer_fn is applied on it to get weight tensor.
optimizer: An instance of `tf.Optimizer` used to train the model. Defaults
to Adagrad optimizer.
activation_fn: Activation function applied to each layer. If `None`, will
use `tf.nn.relu`.
dropout: When not `None`, the probability we will drop out a given
coordinate.
input_layer_partitioner: Optional. Partitioner for input layer. Defaults
to `min_max_variable_partitioner` with `min_slice_size` 64 << 20.
config: `RunConfig` object to configure the runtime settings.
"""
def _model_fn(features, labels, mode, config):
return _dnn_model_fn(
features=features,
labels=labels,
mode=mode,
head=head_lib. # pylint: disable=protected-access
_regression_head_with_mean_squared_error_loss(
label_dimension=label_dimension, weight_column=weight_column),
hidden_units=hidden_units,
feature_columns=tuple(feature_columns or []),
optimizer=optimizer,
activation_fn=activation_fn,
dropout=dropout,
input_layer_partitioner=input_layer_partitioner,
config=config)
super(DNNRegressor, self).__init__(
model_fn=_model_fn, model_dir=model_dir, config=config)