canonical_sets.models.classifiers.ClassifierTF

class ClassifierTF(output_dim)[source]

Bases: Model

Classifier for Keras.

Parameters: output_dim (int) – Output dimension.

Methods

`add_loss`	Add loss tensor(s), potentially dependent on layer inputs.
`add_metric`	Adds metric tensor to the layer.
`add_update`	Add update op(s), potentially dependent on layer inputs.
`add_variable`	Deprecated, do NOT use! Alias for add_weight.
`add_weight`	Adds a new variable to the layer.
`build`	Builds the model based on input shapes received.
`call`	Calls the model on new inputs and returns the outputs as tensors.
`compile`	Configures the model for training.
`compute_loss`	Compute the total loss, validate it, and return it.
`compute_mask`	Computes an output mask tensor.
`compute_metrics`	Update metric states and collect all metrics to be returned.
`compute_output_shape`	Computes the output shape of the layer.
`compute_output_signature`	Compute the output tensor signature of the layer based on the inputs.
`count_params`	Count the total number of scalars composing the weights.
`evaluate`	Returns the loss value & metrics values for the model in test mode.
`evaluate_generator`	Evaluates the model on a data generator.
`finalize_state`	Finalizes the layers state after updating layer weights.
`fit`	Trains the model for a fixed number of epochs (iterations on a dataset).
`fit_generator`	Fits the model on data yielded batch-by-batch by a Python generator.
`from_config`	Creates a layer from its config.
`get_config`	Returns the config of the Model.
`get_input_at`	Retrieves the input tensor(s) of a layer at a given node.
`get_input_mask_at`	Retrieves the input mask tensor(s) of a layer at a given node.
`get_input_shape_at`	Retrieves the input shape(s) of a layer at a given node.
`get_layer`	Retrieves a layer based on either its name (unique) or index.
`get_output_at`	Retrieves the output tensor(s) of a layer at a given node.
`get_output_mask_at`	Retrieves the output mask tensor(s) of a layer at a given node.
`get_output_shape_at`	Retrieves the output shape(s) of a layer at a given node.
`get_weight_paths`	Retrieve all the variables and their paths for the model.
`get_weights`	Retrieves the weights of the model.
`load_weights`	Loads all layer weights, either from a TensorFlow or an HDF5 weight file.
`make_predict_function`	Creates a function that executes one step of inference.
`make_test_function`	Creates a function that executes one step of evaluation.
`make_train_function`	Creates a function that executes one step of training.
`predict`	Generates output predictions for the input samples.
`predict_generator`	Generates predictions for the input samples from a data generator.
`predict_on_batch`	Returns predictions for a single batch of samples.
`predict_step`	The logic for one inference step.
`reset_metrics`	Resets the state of all the metrics in the model.
`reset_states`
`save`	Saves the model to Tensorflow SavedModel or a single HDF5 file.
`save_spec`	Returns the tf.TensorSpec of call inputs as a tuple (args, kwargs).
`save_weights`	Saves all layer weights.
`set_weights`	Sets the weights of the layer, from NumPy arrays.
`summary`	Prints a string summary of the network.
`test_on_batch`	Test the model on a single batch of samples.
`test_step`	The logic for one evaluation step.
`to_json`	Returns a JSON string containing the network configuration.
`to_yaml`	Returns a yaml string containing the network configuration.
`train_on_batch`	Runs a single gradient update on a single batch of data.
`train_step`	The logic for one training step.
`with_name_scope`	Decorator to automatically enter the module name scope.

Attributes

`activity_regularizer`	Optional regularizer function for the output of this layer.
`compute_dtype`	The dtype of the layer's computations.
`distribute_strategy`	The tf.distribute.Strategy this model was created under.
`dtype`	The dtype of the layer weights.
`dtype_policy`	The dtype policy associated with this layer.
`dynamic`	Whether the layer is dynamic (eager-only); set in the constructor.
`inbound_nodes`	Return Functional API nodes upstream of this layer.
`input`	Retrieves the input tensor(s) of a layer.
`input_mask`	Retrieves the input mask tensor(s) of a layer.
`input_shape`	Retrieves the input shape(s) of a layer.
`input_spec`	InputSpec instance(s) describing the input format for this layer.
`layers`
`losses`	List of losses added using the add_loss() API.
`metrics`	Returns the model's metrics added using compile(), add_metric() APIs.
`metrics_names`	Returns the model's display labels for all outputs.
`name`	Name of the layer (string), set in the constructor.
`name_scope`	Returns a tf.name_scope instance for this class.
`non_trainable_variables`	Sequence of non-trainable variables owned by this module and its submodules.
`non_trainable_weights`	List of all non-trainable weights tracked by this layer.
`outbound_nodes`	Return Functional API nodes downstream of this layer.
`output`	Retrieves the output tensor(s) of a layer.
`output_mask`	Retrieves the output mask tensor(s) of a layer.
`output_shape`	Retrieves the output shape(s) of a layer.
`run_eagerly`	Settable attribute indicating whether the model should run eagerly.
`state_updates`	Deprecated, do NOT use!
`stateful`
`submodules`	Sequence of all sub-modules.
`supports_masking`	Whether this layer supports computing a mask using compute_mask.
`trainable`
`trainable_variables`	Sequence of trainable variables owned by this module and its submodules.
`trainable_weights`	List of all trainable weights tracked by this layer.
`updates`
`variable_dtype`	Alias of Layer.dtype, the dtype of the weights.
`variables`	Returns the list of all layer variables/weights.
`weights`	Returns the list of all layer variables/weights.

property activity_regularizer: Optional regularizer function for the output of this layer.

add_loss(losses, **kwargs)

Add loss tensor(s), potentially dependent on layer inputs.

Some losses (for instance, activity regularization losses) may be dependent on the inputs passed when calling a layer. Hence, when reusing the same layer on different inputs a and b, some entries in layer.losses may be dependent on a and some on b. This method automatically keeps track of dependencies.

This method can be used inside a subclassed layer or model’s call function, in which case losses should be a Tensor or list of Tensors.

Example:

```python class MyLayer(tf.keras.layers.Layer):

def call(self, inputs):
self.add_loss(tf.abs(tf.reduce_mean(inputs))) return inputs

```

This method can also be called directly on a Functional Model during construction. In this case, any loss Tensors passed to this Model must be symbolic and be able to be traced back to the model’s Input`s. These losses become part of the model’s topology and are tracked in `get_config.

Example:

`python inputs = tf.keras.Input(shape=(10,)) x = tf.keras.layers.Dense(10)(inputs) outputs = tf.keras.layers.Dense(1)(x) model = tf.keras.Model(inputs, outputs) # Activity regularization. model.add_loss(tf.abs(tf.reduce_mean(x))) `

If this is not the case for your loss (if, for example, your loss references a Variable of one of the model’s layers), you can wrap your loss in a zero-argument lambda. These losses are not tracked as part of the model’s topology since they can’t be serialized.

Example:

`python inputs = tf.keras.Input(shape=(10,)) d = tf.keras.layers.Dense(10) x = d(inputs) outputs = tf.keras.layers.Dense(1)(x) model = tf.keras.Model(inputs, outputs) # Weight regularization. model.add_loss(lambda: tf.reduce_mean(d.kernel)) `

Parameters

losses – Loss tensor, or list/tuple of tensors. Rather than tensors, losses may also be zero-argument callables which create a loss tensor.
**kwargs – Used for backwards compatibility only.

add_metric(value, name=None, **kwargs)

Adds metric tensor to the layer.

This method can be used inside the call() method of a subclassed layer or model.

```python class MyMetricLayer(tf.keras.layers.Layer):

def __init__(self):
super(MyMetricLayer, self).__init__(name=’my_metric_layer’) self.mean = tf.keras.metrics.Mean(name=’metric_1’)

def call(self, inputs):
self.add_metric(self.mean(inputs)) self.add_metric(tf.reduce_sum(inputs), name=’metric_2’) return inputs

```

This method can also be called directly on a Functional Model during construction. In this case, any tensor passed to this Model must be symbolic and be able to be traced back to the model’s Input`s. These metrics become part of the model’s topology and are tracked when you save the model via `save().

`python inputs = tf.keras.Input(shape=(10,)) x = tf.keras.layers.Dense(10)(inputs) outputs = tf.keras.layers.Dense(1)(x) model = tf.keras.Model(inputs, outputs) model.add_metric(math_ops.reduce_sum(x), name='metric_1') `

Note: Calling add_metric() with the result of a metric object on a Functional Model, as shown in the example below, is not supported. This is because we cannot trace the metric result tensor back to the model’s inputs.

`python inputs = tf.keras.Input(shape=(10,)) x = tf.keras.layers.Dense(10)(inputs) outputs = tf.keras.layers.Dense(1)(x) model = tf.keras.Model(inputs, outputs) model.add_metric(tf.keras.metrics.Mean()(x), name='metric_1') `

Parameters

value – Metric tensor.
name – String metric name.
**kwargs – Additional keyword arguments for backward compatibility. Accepted values: aggregation - When the value tensor provided is not the result of calling a keras.Metric instance, it will be aggregated by default using a keras.Metric.Mean.

add_update(updates)

Add update op(s), potentially dependent on layer inputs.

Weight updates (for instance, the updates of the moving mean and variance in a BatchNormalization layer) may be dependent on the inputs passed when calling a layer. Hence, when reusing the same layer on different inputs a and b, some entries in layer.updates may be dependent on a and some on b. This method automatically keeps track of dependencies.

This call is ignored when eager execution is enabled (in that case, variable updates are run on the fly and thus do not need to be tracked for later execution).

Parameters: updates – Update op, or list/tuple of update ops, or zero-arg callable that returns an update op. A zero-arg callable should be passed in order to disable running the updates by setting trainable=False on this Layer, when executing in Eager mode.

add_variable(*args, **kwargs): Deprecated, do NOT use! Alias for add_weight.

add_weight(name=None, shape=None, dtype=None, initializer=None, regularizer=None, trainable=None, constraint=None, use_resource=None, synchronization=VariableSynchronization.AUTO, aggregation=VariableAggregationV2.NONE, **kwargs)

Adds a new variable to the layer.

Parameters

name – Variable name.
shape – Variable shape. Defaults to scalar if unspecified.
dtype – The type of the variable. Defaults to self.dtype.
initializer – Initializer instance (callable).
regularizer – Regularizer instance (callable).
trainable – Boolean, whether the variable should be part of the layer’s “trainable_variables” (e.g. variables, biases) or “non_trainable_variables” (e.g. BatchNorm mean and variance). Note that trainable cannot be True if synchronization is set to ON_READ.
constraint – Constraint instance (callable).
use_resource – Whether to use a ResourceVariable or not. See [this guide]( https://www.tensorflow.org/guide/migrate/tf1_vs_tf2#resourcevariables_instead_of_referencevariables) for more information.
synchronization – Indicates when a distributed a variable will be aggregated. Accepted values are constants defined in the class tf.VariableSynchronization. By default the synchronization is set to AUTO and the current DistributionStrategy chooses when to synchronize. If synchronization is set to ON_READ, trainable must not be set to True.
aggregation – Indicates how a distributed variable will be aggregated. Accepted values are constants defined in the class tf.VariableAggregation.
**kwargs – Additional keyword arguments. Accepted values are getter, collections, experimental_autocast and caching_device.

Returns

The variable created.

Raises

ValueError – When giving unsupported dtype and no initializer or when trainable has been set to True with synchronization set as ON_READ.

build(input_shape)

Builds the model based on input shapes received.

This is to be used for subclassed models, which do not know at instantiation time what their inputs look like.

This method only exists for users who want to call model.build() in a standalone way (as a substitute for calling the model on real data to build it). It will never be called by the framework (and thus it will never throw unexpected errors in an unrelated workflow).

Parameters

input_shape – Single tuple, TensorShape instance, or list/dict of shapes, where shapes are tuples, integers, or TensorShape instances.

Raises

ValueError –
1. In case of invalid user-provided data (not of type tuple, list, TensorShape, or dict). 2. If the model requires call arguments that are agnostic to the input shapes (positional or keyword arg in call signature). 3. If not all layers were properly built. 4. If float type inputs are not supported within the layers.
In each of these cases, the user should build their model by calling –
it on real tensor data. –

call(x)[source]

Calls the model on new inputs and returns the outputs as tensors.

In this case call() just reapplies all ops in the graph to the new inputs (e.g. build a new computational graph from the provided inputs).

Note: This method should not be called directly. It is only meant to be overridden when subclassing tf.keras.Model. To call a model on an input, always use the __call__() method, i.e. model(inputs), which relies on the underlying call() method.

Parameters

inputs – Input tensor, or dict/list/tuple of input tensors.
training – Boolean or boolean scalar tensor, indicating whether to run the Network in training mode or inference mode.
mask – A mask or list of masks. A mask can be either a boolean tensor or None (no mask). For more details, check the guide [here](https://www.tensorflow.org/guide/keras/masking_and_padding).

Returns

A tensor if there is a single output, or a list of tensors if there are more than one outputs.

compile(optimizer='rmsprop', loss=None, metrics=None, loss_weights=None, weighted_metrics=None, run_eagerly=None, steps_per_execution=None, jit_compile=None, **kwargs)

Configures the model for training.

Example:

```python model.compile(optimizer=tf.keras.optimizers.Adam(learning_rate=1e-3),

loss=tf.keras.losses.BinaryCrossentropy(), metrics=[tf.keras.metrics.BinaryAccuracy(),

tf.keras.metrics.FalseNegatives()])

```

Parameters

optimizer – String (name of optimizer) or optimizer instance. See tf.keras.optimizers.
loss – Loss function. May be a string (name of loss function), or a tf.keras.losses.Loss instance. See tf.keras.losses. A loss function is any callable with the signature loss = fn(y_true, y_pred), where y_true are the ground truth values, and y_pred are the model’s predictions. y_true should have shape (batch_size, d0, .. dN) (except in the case of sparse loss functions such as sparse categorical crossentropy which expects integer arrays of shape (batch_size, d0, .. dN-1)). y_pred should have shape (batch_size, d0, .. dN). The loss function should return a float tensor. If a custom Loss instance is used and reduction is set to None, return value has shape (batch_size, d0, .. dN-1) i.e. per-sample or per-timestep loss values; otherwise, it is a scalar. If the model has multiple outputs, you can use a different loss on each output by passing a dictionary or a list of losses. The loss value that will be minimized by the model will then be the sum of all individual losses, unless loss_weights is specified.
metrics – List of metrics to be evaluated by the model during training and testing. Each of this can be a string (name of a built-in function), function or a tf.keras.metrics.Metric instance. See tf.keras.metrics. Typically you will use metrics=[‘accuracy’]. A function is any callable with the signature result = fn(y_true, y_pred). To specify different metrics for different outputs of a multi-output model, you could also pass a dictionary, such as metrics={‘output_a’:’accuracy’, ‘output_b’:[‘accuracy’, ‘mse’]}. You can also pass a list to specify a metric or a list of metrics for each output, such as metrics=[[‘accuracy’], [‘accuracy’, ‘mse’]] or metrics=[‘accuracy’, [‘accuracy’, ‘mse’]]. When you pass the strings ‘accuracy’ or ‘acc’, we convert this to one of tf.keras.metrics.BinaryAccuracy, tf.keras.metrics.CategoricalAccuracy, tf.keras.metrics.SparseCategoricalAccuracy based on the loss function used and the model output shape. We do a similar conversion for the strings ‘crossentropy’ and ‘ce’ as well. The metrics passed here are evaluated without sample weighting; if you would like sample weighting to apply, you can specify your metrics via the weighted_metrics argument instead.
loss_weights – Optional list or dictionary specifying scalar coefficients (Python floats) to weight the loss contributions of different model outputs. The loss value that will be minimized by the model will then be the weighted sum of all individual losses, weighted by the loss_weights coefficients. If a list, it is expected to have a 1:1 mapping to the model’s outputs. If a dict, it is expected to map output names (strings) to scalar coefficients.
weighted_metrics – List of metrics to be evaluated and weighted by sample_weight or class_weight during training and testing.
run_eagerly – Bool. Defaults to False. If True, this Model’s logic will not be wrapped in a tf.function. Recommended to leave this as None unless your Model cannot be run inside a tf.function. run_eagerly=True is not supported when using tf.distribute.experimental.ParameterServerStrategy.
steps_per_execution – Int. Defaults to 1. The number of batches to run during each tf.function call. Running multiple batches inside a single tf.function call can greatly improve performance on TPUs or small models with a large Python overhead. At most, one full epoch will be run each execution. If a number larger than the size of the epoch is passed, the execution will be truncated to the size of the epoch. Note that if steps_per_execution is set to N, Callback.on_batch_begin and Callback.on_batch_end methods will only be called every N batches (i.e. before/after each tf.function execution).
jit_compile – If True, compile the model training step with XLA. [XLA](https://www.tensorflow.org/xla) is an optimizing compiler for machine learning. jit_compile is not enabled for by default. This option cannot be enabled with run_eagerly=True. Note that jit_compile=True may not necessarily work for all models. For more information on supported operations please refer to the [XLA documentation](https://www.tensorflow.org/xla). Also refer to [known XLA issues](https://www.tensorflow.org/xla/known_issues) for more details.
**kwargs – Arguments supported for backwards compatibility only.

property compute_dtype

The dtype of the layer’s computations.

This is equivalent to Layer.dtype_policy.compute_dtype. Unless mixed precision is used, this is the same as Layer.dtype, the dtype of the weights.

Layers automatically cast their inputs to the compute dtype, which causes computations and the output to be in the compute dtype as well. This is done by the base Layer class in Layer.__call__, so you do not have to insert these casts if implementing your own layer.

Layers often perform certain internal computations in higher precision when compute_dtype is float16 or bfloat16 for numeric stability. The output will still typically be float16 or bfloat16 in such cases.

Returns: The layer’s compute dtype.

compute_loss(x=None, y=None, y_pred=None, sample_weight=None)

Compute the total loss, validate it, and return it.

Subclasses can optionally override this method to provide custom loss computation logic.

Example: ```python class MyModel(tf.keras.Model):

def __init__(self, *args, **kwargs):
super(MyModel, self).__init__(*args, **kwargs) self.loss_tracker = tf.keras.metrics.Mean(name=’loss’)

def compute_loss(self, x, y, y_pred, sample_weight):
loss = tf.reduce_mean(tf.math.squared_difference(y_pred, y)) loss += tf.add_n(self.losses) self.loss_tracker.update_state(loss) return loss

def reset_metrics(self):
self.loss_tracker.reset_states()

@property def metrics(self):

return [self.loss_tracker]

tensors = tf.random.uniform((10, 10)), tf.random.uniform((10,)) dataset = tf.data.Dataset.from_tensor_slices(tensors).repeat().batch(1)

inputs = tf.keras.layers.Input(shape=(10,), name=’my_input’) outputs = tf.keras.layers.Dense(10)(inputs) model = MyModel(inputs, outputs) model.add_loss(tf.reduce_sum(outputs))

optimizer = tf.keras.optimizers.SGD() model.compile(optimizer, loss=’mse’, steps_per_execution=10) model.fit(dataset, epochs=2, steps_per_epoch=10) print(‘My custom loss: ‘, model.loss_tracker.result().numpy()) ```

Parameters

x – Input data.
y – Target data.
y_pred – Predictions returned by the model (output of model(x))
sample_weight – Sample weights for weighting the loss function.

Returns

The total loss as a tf.Tensor, or None if no loss results (which is the case when called by Model.test_step).

compute_mask(inputs, mask=None)

Computes an output mask tensor.

Parameters

inputs – Tensor or list of tensors.
mask – Tensor or list of tensors.

Returns

None or a tensor (or list of tensors,: one per output tensor of the layer).

compute_metrics(x, y, y_pred, sample_weight)

Update metric states and collect all metrics to be returned.

Subclasses can optionally override this method to provide custom metric updating and collection logic.

Example: ```python class MyModel(tf.keras.Sequential):

def compute_metrics(self, x, y, y_pred, sample_weight):

# This super call updates self.compiled_metrics and returns # results for all metrics listed in self.metrics. metric_results = super(MyModel, self).compute_metrics(

x, y, y_pred, sample_weight)

# Note that self.custom_metric is not listed in self.metrics. self.custom_metric.update_state(x, y, y_pred, sample_weight) metric_results[‘custom_metric_name’] = self.custom_metric.result() return metric_results

```

Parameters

x – Input data.
y – Target data.
y_pred – Predictions returned by the model (output of model.call(x))
sample_weight – Sample weights for weighting the loss function.

Returns

A dict containing values that will be passed to tf.keras.callbacks.CallbackList.on_train_batch_end(). Typically, the values of the metrics listed in self.metrics are returned. Example: {‘loss’: 0.2, ‘accuracy’: 0.7}.

compute_output_shape(input_shape)

Computes the output shape of the layer.

This method will cause the layer’s state to be built, if that has not happened before. This requires that the layer will later be used with inputs that match the input shape provided here.

Parameters: input_shape – Shape tuple (tuple of integers) or list of shape tuples (one per output tensor of the layer). Shape tuples can include None for free dimensions, instead of an integer.
Returns: An input shape tuple.

compute_output_signature(input_signature)

Compute the output tensor signature of the layer based on the inputs.

Unlike a TensorShape object, a TensorSpec object contains both shape and dtype information for a tensor. This method allows layers to provide output dtype information if it is different from the input dtype. For any layer that doesn’t implement this function, the framework will fall back to use compute_output_shape, and will assume that the output dtype matches the input dtype.

Parameters

input_signature – Single TensorSpec or nested structure of TensorSpec objects, describing a candidate input for the layer.

Returns

Single TensorSpec or nested structure of TensorSpec objects,: describing how the layer would transform the provided input.

Raises

TypeError – If input_signature contains a non-TensorSpec object.

count_params()

Count the total number of scalars composing the weights.

Returns: An integer count.
Raises: ValueError – if the layer isn’t yet built (in which case its weights aren’t yet defined).

property distribute_strategy: The tf.distribute.Strategy this model was created under.

property dtype

The dtype of the layer weights.

This is equivalent to Layer.dtype_policy.variable_dtype. Unless mixed precision is used, this is the same as Layer.compute_dtype, the dtype of the layer’s computations.

property dtype_policy

The dtype policy associated with this layer.

This is an instance of a tf.keras.mixed_precision.Policy.

property dynamic: Whether the layer is dynamic (eager-only); set in the constructor.

evaluate(x=None, y=None, batch_size=None, verbose='auto', sample_weight=None, steps=None, callbacks=None, max_queue_size=10, workers=1, use_multiprocessing=False, return_dict=False, **kwargs)

Returns the loss value & metrics values for the model in test mode.

Computation is done in batches (see the batch_size arg.)

Parameters

x –
Input data. It could be: - A Numpy array (or array-like), or a list of arrays

(in case the model has multiple inputs).
- A TensorFlow tensor, or a list of tensors (in case the model has multiple inputs).
- A dict mapping input names to the corresponding array/tensors, if the model has named inputs.
- A tf.data dataset. Should return a tuple of either (inputs, targets) or (inputs, targets, sample_weights).
- A generator or keras.utils.Sequence returning (inputs, targets) or (inputs, targets, sample_weights).
A more detailed description of unpacking behavior for iterator types (Dataset, generator, Sequence) is given in the Unpacking behavior for iterator-like inputs section of Model.fit.
y – Target data. Like the input data x, it could be either Numpy array(s) or TensorFlow tensor(s). It should be consistent with x (you cannot have Numpy inputs and tensor targets, or inversely). If x is a dataset, generator or keras.utils.Sequence instance, y should not be specified (since targets will be obtained from the iterator/dataset).
batch_size – Integer or None. Number of samples per batch of computation. If unspecified, batch_size will default to 32. Do not specify the batch_size if your data is in the form of a dataset, generators, or keras.utils.Sequence instances (since they generate batches).
verbose – “auto”, 0, 1, or 2. Verbosity mode. 0 = silent, 1 = progress bar, 2 = single line. “auto” defaults to 1 for most cases, and to 2 when used with ParameterServerStrategy. Note that the progress bar is not particularly useful when logged to a file, so verbose=2 is recommended when not running interactively (e.g. in a production environment).
sample_weight –
Optional Numpy array of weights for the test samples, used for weighting the loss function. You can either pass a flat (1D) Numpy array with the same length as the input samples

(1:1 mapping between weights and samples), or in the case of
temporal data, you can pass a 2D array with shape (samples, sequence_length), to apply a different weight to every timestep of every sample. This argument is not supported when x is a dataset, instead pass sample weights as the third element of x.
steps – Integer or None. Total number of steps (batches of samples) before declaring the evaluation round finished. Ignored with the default value of None. If x is a tf.data dataset and steps is None, ‘evaluate’ will run until the dataset is exhausted. This argument is not supported with array inputs.
callbacks – List of keras.callbacks.Callback instances. List of callbacks to apply during evaluation. See [callbacks](/api_docs/python/tf/keras/callbacks).
max_queue_size – Integer. Used for generator or keras.utils.Sequence input only. Maximum size for the generator queue. If unspecified, max_queue_size will default to 10.
workers – Integer. Used for generator or keras.utils.Sequence input only. Maximum number of processes to spin up when using process-based threading. If unspecified, workers will default to 1.
use_multiprocessing – Boolean. Used for generator or keras.utils.Sequence input only. If True, use process-based threading. If unspecified, use_multiprocessing will default to False. Note that because this implementation relies on multiprocessing, you should not pass non-picklable arguments to the generator as they can’t be passed easily to children processes.
return_dict – If True, loss and metric results are returned as a dict, with each key being the name of the metric. If False, they are returned as a list.
**kwargs – Unused at this time.

See the discussion of Unpacking behavior for iterator-like inputs for Model.fit.

Returns: Scalar test loss (if the model has a single output and no metrics) or list of scalars (if the model has multiple outputs and/or metrics). The attribute model.metrics_names will give you the display labels for the scalar outputs.
Raises: RuntimeError – If model.evaluate is wrapped in a tf.function.

evaluate_generator(generator, steps=None, callbacks=None, max_queue_size=10, workers=1, use_multiprocessing=False, verbose=0)

Evaluates the model on a data generator.

DEPRECATED:: Model.evaluate now supports generators, so there is no longer any need to use this endpoint.

finalize_state()

Finalizes the layers state after updating layer weights.

This function can be subclassed in a layer and will be called after updating a layer weights. It can be overridden to finalize any additional layer state after a weight update.

This function will be called after weights of a layer have been restored from a loaded model.

fit(x=None, y=None, batch_size=None, epochs=1, verbose='auto', callbacks=None, validation_split=0.0, validation_data=None, shuffle=True, class_weight=None, sample_weight=None, initial_epoch=0, steps_per_epoch=None, validation_steps=None, validation_batch_size=None, validation_freq=1, max_queue_size=10, workers=1, use_multiprocessing=False)

Trains the model for a fixed number of epochs (iterations on a dataset).

Parameters

x –
Input data. It could be: - A Numpy array (or array-like), or a list of arrays

(in case the model has multiple inputs).
- A TensorFlow tensor, or a list of tensors (in case the model has multiple inputs).
- A dict mapping input names to the corresponding array/tensors, if the model has named inputs.
- A tf.data dataset. Should return a tuple of either (inputs, targets) or (inputs, targets, sample_weights).
- A generator or keras.utils.Sequence returning (inputs, targets) or (inputs, targets, sample_weights).
- A tf.keras.utils.experimental.DatasetCreator, which wraps a callable that takes a single argument of type tf.distribute.InputContext, and returns a tf.data.Dataset. DatasetCreator should be used when users prefer to specify the per-replica batching and sharding logic for the Dataset. See tf.keras.utils.experimental.DatasetCreator doc for more information.
A more detailed description of unpacking behavior for iterator types (Dataset, generator, Sequence) is given below. If these include sample_weights as a third component, note that sample weighting applies to the weighted_metrics argument but not the metrics argument in compile(). If using tf.distribute.experimental.ParameterServerStrategy, only DatasetCreator type is supported for x.
y – Target data. Like the input data x, it could be either Numpy array(s) or TensorFlow tensor(s). It should be consistent with x (you cannot have Numpy inputs and tensor targets, or inversely). If x is a dataset, generator, or keras.utils.Sequence instance, y should not be specified (since targets will be obtained from x).
batch_size – Integer or None. Number of samples per gradient update. If unspecified, batch_size will default to 32. Do not specify the batch_size if your data is in the form of datasets, generators, or keras.utils.Sequence instances (since they generate batches).
epochs – Integer. Number of epochs to train the model. An epoch is an iteration over the entire x and y data provided (unless the steps_per_epoch flag is set to something other than None). Note that in conjunction with initial_epoch, epochs is to be understood as “final epoch”. The model is not trained for a number of iterations given by epochs, but merely until the epoch of index epochs is reached.
verbose – ‘auto’, 0, 1, or 2. Verbosity mode. 0 = silent, 1 = progress bar, 2 = one line per epoch. ‘auto’ defaults to 1 for most cases, but 2 when used with ParameterServerStrategy. Note that the progress bar is not particularly useful when logged to a file, so verbose=2 is recommended when not running interactively (eg, in a production environment).
callbacks – List of keras.callbacks.Callback instances. List of callbacks to apply during training. See tf.keras.callbacks. Note tf.keras.callbacks.ProgbarLogger and tf.keras.callbacks.History callbacks are created automatically and need not be passed into model.fit. tf.keras.callbacks.ProgbarLogger is created or not based on verbose argument to model.fit. Callbacks with batch-level calls are currently unsupported with tf.distribute.experimental.ParameterServerStrategy, and users are advised to implement epoch-level calls instead with an appropriate steps_per_epoch value.
validation_split – Float between 0 and 1. Fraction of the training data to be used as validation data. The model will set apart this fraction of the training data, will not train on it, and will evaluate the loss and any model metrics on this data at the end of each epoch. The validation data is selected from the last samples in the x and y data provided, before shuffling. This argument is not supported when x is a dataset, generator or keras.utils.Sequence instance. If both validation_data and validation_split are provided, validation_data will override validation_split. validation_split is not yet supported with tf.distribute.experimental.ParameterServerStrategy.
validation_data –
Data on which to evaluate the loss and any model metrics at the end of each epoch. The model will not be trained on this data. Thus, note the fact that the validation loss of data provided using validation_split or validation_data is not affected by regularization layers like noise and dropout. validation_data will override validation_split. validation_data could be:
- A tuple (x_val, y_val) of Numpy arrays or tensors.
- A tuple (x_val, y_val, val_sample_weights) of NumPy arrays.
- A tf.data.Dataset.
- A Python generator or keras.utils.Sequence returning
(inputs, targets) or (inputs, targets, sample_weights).
validation_data is not yet supported with tf.distribute.experimental.ParameterServerStrategy.
shuffle – Boolean (whether to shuffle the training data before each epoch) or str (for ‘batch’). This argument is ignored when x is a generator or an object of tf.data.Dataset. ‘batch’ is a special option for dealing with the limitations of HDF5 data; it shuffles in batch-sized chunks. Has no effect when steps_per_epoch is not None.
class_weight – Optional dictionary mapping class indices (integers) to a weight (float) value, used for weighting the loss function (during training only). This can be useful to tell the model to “pay more attention” to samples from an under-represented class.
sample_weight – Optional Numpy array of weights for the training samples, used for weighting the loss function (during training only). You can either pass a flat (1D) Numpy array with the same length as the input samples (1:1 mapping between weights and samples), or in the case of temporal data, you can pass a 2D array with shape (samples, sequence_length), to apply a different weight to every timestep of every sample. This argument is not supported when x is a dataset, generator, or keras.utils.Sequence instance, instead provide the sample_weights as the third element of x. Note that sample weighting does not apply to metrics specified via the metrics argument in compile(). To apply sample weighting to your metrics, you can specify them via the weighted_metrics in compile() instead.
initial_epoch – Integer. Epoch at which to start training (useful for resuming a previous training run).
steps_per_epoch –
Integer or None. Total number of steps (batches of samples) before declaring one epoch finished and starting the next epoch. When training with input tensors such as TensorFlow data tensors, the default None is equal to the number of samples in your dataset divided by the batch size, or 1 if that cannot be determined. If x is a tf.data dataset, and ‘steps_per_epoch’ is None, the epoch will run until the input dataset is exhausted. When passing an infinitely repeating dataset, you must specify the steps_per_epoch argument. If steps_per_epoch=-1 the training will run indefinitely with an infinitely repeating dataset. This argument is not supported with array inputs. When using tf.distribute.experimental.ParameterServerStrategy:
- steps_per_epoch=None is not supported.
validation_steps – Only relevant if validation_data is provided and is a tf.data dataset. Total number of steps (batches of samples) to draw before stopping when performing validation at the end of every epoch. If ‘validation_steps’ is None, validation will run until the validation_data dataset is exhausted. In the case of an infinitely repeated dataset, it will run into an infinite loop. If ‘validation_steps’ is specified and only part of the dataset will be consumed, the evaluation will start from the beginning of the dataset at each epoch. This ensures that the same validation samples are used every time.
validation_batch_size – Integer or None. Number of samples per validation batch. If unspecified, will default to batch_size. Do not specify the validation_batch_size if your data is in the form of datasets, generators, or keras.utils.Sequence instances (since they generate batches).
validation_freq – Only relevant if validation data is provided. Integer or collections.abc.Container instance (e.g. list, tuple, etc.). If an integer, specifies how many training epochs to run before a new validation run is performed, e.g. validation_freq=2 runs validation every 2 epochs. If a Container, specifies the epochs on which to run validation, e.g. validation_freq=[1, 2, 10] runs validation at the end of the 1st, 2nd, and 10th epochs.
max_queue_size – Integer. Used for generator or keras.utils.Sequence input only. Maximum size for the generator queue. If unspecified, max_queue_size will default to 10.
workers – Integer. Used for generator or keras.utils.Sequence input only. Maximum number of processes to spin up when using process-based threading. If unspecified, workers will default to 1.
use_multiprocessing – Boolean. Used for generator or keras.utils.Sequence input only. If True, use process-based threading. If unspecified, use_multiprocessing will default to False. Note that because this implementation relies on multiprocessing, you should not pass non-picklable arguments to the generator as they can’t be passed easily to children processes.

Unpacking behavior for iterator-like inputs:

A common pattern is to pass a tf.data.Dataset, generator, or

tf.keras.utils.Sequence to the x argument of fit, which will in fact yield not only features (x) but optionally targets (y) and sample weights. Keras requires that the output of such iterator-likes be unambiguous. The iterator should return a tuple of length 1, 2, or 3, where the optional second and third elements will be used for y and sample_weight respectively. Any other type provided will be wrapped in a length one tuple, effectively treating everything as ‘x’. When yielding dicts, they should still adhere to the top-level tuple structure. e.g. ({“x0”: x0, “x1”: x1}, y). Keras will not attempt to separate features, targets, and weights from the keys of a single dict.

A notable unsupported data type is the namedtuple. The reason is

that it behaves like both an ordered datatype (tuple) and a mapping datatype (dict). So given a namedtuple of the form:

namedtuple(“example_tuple”, [“y”, “x”])

it is ambiguous whether to reverse the order of the elements when interpreting the value. Even worse is a tuple of the form:

namedtuple(“other_tuple”, [“x”, “y”, “z”])

where it is unclear if the tuple was intended to be unpacked into x, y, and sample_weight or passed through as a single element to x. As a result the data processing code will simply raise a ValueError if it encounters a namedtuple. (Along with instructions to remedy the issue.)

Returns

A History object. Its History.history attribute is a record of training loss values and metrics values at successive epochs, as well as validation loss values and validation metrics values (if applicable).

Raises

RuntimeError –
1. If the model was never compiled or,
2. If model.fit is wrapped in tf.function. –
ValueError – In case of mismatch between the provided input data and what the model expects or when the input data is empty.

fit_generator(generator, steps_per_epoch=None, epochs=1, verbose=1, callbacks=None, validation_data=None, validation_steps=None, validation_freq=1, class_weight=None, max_queue_size=10, workers=1, use_multiprocessing=False, shuffle=True, initial_epoch=0)

Fits the model on data yielded batch-by-batch by a Python generator.

DEPRECATED:: Model.fit now supports generators, so there is no longer any need to use this endpoint.

classmethod from_config(config, custom_objects=None)

Creates a layer from its config.

This method is the reverse of get_config, capable of instantiating the same layer from the config dictionary. It does not handle layer connectivity (handled by Network), nor weights (handled by set_weights).

Parameters: config – A Python dictionary, typically the output of get_config.
Returns: A layer instance.

get_config()

Returns the config of the Model.

Config is a Python dictionary (serializable) containing the configuration of an object, which in this case is a Model. This allows the Model to be be reinstantiated later (without its trained weights) from this configuration.

Note that get_config() does not guarantee to return a fresh copy of dict every time it is called. The callers should make a copy of the returned dict if they want to modify it.

Developers of subclassed Model are advised to override this method, and continue to update the dict from super(MyModel, self).get_config() to provide the proper configuration of this Model. The default config is an empty dict. Optionally, raise NotImplementedError to allow Keras to attempt a default serialization.

Returns: Python dictionary containing the configuration of this Model.

get_input_at(node_index)

Retrieves the input tensor(s) of a layer at a given node.

Parameters: node_index – Integer, index of the node from which to retrieve the attribute. E.g. node_index=0 will correspond to the first input node of the layer.
Returns: A tensor (or list of tensors if the layer has multiple inputs).
Raises: RuntimeError – If called in Eager mode.

get_input_mask_at(node_index)

Retrieves the input mask tensor(s) of a layer at a given node.

Parameters: node_index – Integer, index of the node from which to retrieve the attribute. E.g. node_index=0 will correspond to the first time the layer was called.
Returns: A mask tensor (or list of tensors if the layer has multiple inputs).

get_input_shape_at(node_index)

Retrieves the input shape(s) of a layer at a given node.

Parameters: node_index – Integer, index of the node from which to retrieve the attribute. E.g. node_index=0 will correspond to the first time the layer was called.
Returns: A shape tuple (or list of shape tuples if the layer has multiple inputs).
Raises: RuntimeError – If called in Eager mode.

get_layer(name=None, index=None)

Retrieves a layer based on either its name (unique) or index.

If name and index are both provided, index will take precedence. Indices are based on order of horizontal graph traversal (bottom-up).

Parameters

name – String, name of layer.
index – Integer, index of layer.

Returns

A layer instance.

get_output_at(node_index)

Retrieves the output tensor(s) of a layer at a given node.

Parameters: node_index – Integer, index of the node from which to retrieve the attribute. E.g. node_index=0 will correspond to the first output node of the layer.
Returns: A tensor (or list of tensors if the layer has multiple outputs).
Raises: RuntimeError – If called in Eager mode.

get_output_mask_at(node_index)

Retrieves the output mask tensor(s) of a layer at a given node.

Parameters: node_index – Integer, index of the node from which to retrieve the attribute. E.g. node_index=0 will correspond to the first time the layer was called.
Returns: A mask tensor (or list of tensors if the layer has multiple outputs).

get_output_shape_at(node_index)

Retrieves the output shape(s) of a layer at a given node.

Parameters: node_index – Integer, index of the node from which to retrieve the attribute. E.g. node_index=0 will correspond to the first time the layer was called.
Returns: A shape tuple (or list of shape tuples if the layer has multiple outputs).
Raises: RuntimeError – If called in Eager mode.

get_weight_paths()

Retrieve all the variables and their paths for the model.

The variable path (string) is a stable key to indentify a tf.Variable instance owned by the model. It can be used to specify variable-specific configurations (e.g. DTensor, quantization) from a global view.

This method returns a dict with weight object paths as keys and the corresponding tf.Variable instances as values.

Note that if the model is a subclassed model and the weights haven’t been initialized, an empty dict will be returned.

Returns

A dict where keys are variable paths and values are tf.Variable: instances.

Example:

```python class SubclassModel(tf.keras.Model):

def __init__(self, name=None):
super().__init__(name=name) self.d1 = tf.keras.layers.Dense(10) self.d2 = tf.keras.layers.Dense(20)

def call(self, inputs):
x = self.d1(inputs) return self.d2(x)

model = SubclassModel() model(tf.zeros((10, 10))) weight_paths = model.get_weight_paths() # weight_paths: # { # ‘d1.kernel’: model.d1.kernel, # ‘d1.bias’: model.d1.bias, # ‘d2.kernel’: model.d2.kernel, # ‘d2.bias’: model.d2.bias, # }

# Functional model inputs = tf.keras.Input((10,), batch_size=10) x = tf.keras.layers.Dense(20, name=’d1’)(inputs) output = tf.keras.layers.Dense(30, name=’d2’)(x) model = tf.keras.Model(inputs, output) d1 = model.layers[1] d2 = model.layers[2] weight_paths = model.get_weight_paths() # weight_paths: # { # ‘d1.kernel’: d1.kernel, # ‘d1.bias’: d1.bias, # ‘d2.kernel’: d2.kernel, # ‘d2.bias’: d2.bias, # } ```

get_weights()

Retrieves the weights of the model.

Returns: A flat list of Numpy arrays.

property inbound_nodes: Return Functional API nodes upstream of this layer.

property input

Retrieves the input tensor(s) of a layer.

Only applicable if the layer has exactly one input, i.e. if it is connected to one incoming layer.

Returns

Input tensor or list of input tensors.

Raises

RuntimeError – If called in Eager mode.
AttributeError – If no inbound nodes are found.

property input_mask

Retrieves the input mask tensor(s) of a layer.

Only applicable if the layer has exactly one inbound node, i.e. if it is connected to one incoming layer.

Returns

Input mask tensor (potentially None) or list of input mask tensors.

Raises

AttributeError – if the layer is connected to
more than one incoming layers. –

property input_shape

Retrieves the input shape(s) of a layer.

Only applicable if the layer has exactly one input, i.e. if it is connected to one incoming layer, or if all inputs have the same shape.

Returns

Input shape, as an integer shape tuple (or list of shape tuples, one tuple per input tensor).

Raises

AttributeError – if the layer has no defined input_shape.
RuntimeError – if called in Eager mode.

property input_spec

InputSpec instance(s) describing the input format for this layer.

When you create a layer subclass, you can set self.input_spec to enable the layer to run input compatibility checks when it is called. Consider a Conv2D layer: it can only be called on a single input tensor of rank 4. As such, you can set, in __init__():

`python self.input_spec = tf.keras.layers.InputSpec(ndim=4) `

Now, if you try to call the layer on an input that isn’t rank 4 (for instance, an input of shape (2,), it will raise a nicely-formatted error:

` ValueError: Input 0 of layer conv2d is incompatible with the layer: expected ndim=4, found ndim=1. Full shape received: [2] `

Input checks that can be specified via input_spec include: - Structure (e.g. a single input, a list of 2 inputs, etc) - Shape - Rank (ndim) - Dtype

For more information, see tf.keras.layers.InputSpec.

Returns: A tf.keras.layers.InputSpec instance, or nested structure thereof.

load_weights(filepath, by_name=False, skip_mismatch=False, options=None)

Loads all layer weights, either from a TensorFlow or an HDF5 weight file.

If by_name is False weights are loaded based on the network’s topology. This means the architecture should be the same as when the weights were saved. Note that layers that don’t have weights are not taken into account in the topological ordering, so adding or removing layers is fine as long as they don’t have weights.

If by_name is True, weights are loaded into layers only if they share the same name. This is useful for fine-tuning or transfer-learning models where some of the layers have changed.

Only topological loading (by_name=False) is supported when loading weights from the TensorFlow format. Note that topological loading differs slightly between TensorFlow and HDF5 formats for user-defined classes inheriting from tf.keras.Model: HDF5 loads based on a flattened list of weights, while the TensorFlow format loads based on the object-local names of attributes to which layers are assigned in the Model’s constructor.

Parameters

filepath – String, path to the weights file to load. For weight files in TensorFlow format, this is the file prefix (the same as was passed to save_weights). This can also be a path to a SavedModel saved from model.save.
by_name – Boolean, whether to load weights by name or by topological order. Only topological loading is supported for weight files in TensorFlow format.
skip_mismatch – Boolean, whether to skip loading of layers where there is a mismatch in the number of weights, or a mismatch in the shape of the weight (only valid when by_name=True).
options – Optional tf.train.CheckpointOptions object that specifies options for loading weights.

Returns

When loading a weight file in TensorFlow format, returns the same status object as tf.train.Checkpoint.restore. When graph building, restore ops are run automatically as soon as the network is built (on first call for user-defined classes inheriting from Model, immediately if it is already built).

When loading weights in HDF5 format, returns None.

Raises

ImportError – If h5py is not available and the weight file is in HDF5 format.
ValueError – If skip_mismatch is set to True when by_name is False.

property losses

List of losses added using the add_loss() API.

Variable regularization tensors are created when this property is accessed, so it is eager safe: accessing losses under a tf.GradientTape will propagate gradients back to the corresponding variables.

Examples:

>>> class MyLayer(tf.keras.layers.Layer):
...   def call(self, inputs):
...     self.add_loss(tf.abs(tf.reduce_mean(inputs)))
...     return inputs
>>> l = MyLayer()
>>> l(np.ones((10, 1)))
>>> l.losses
[1.0]

>>> inputs = tf.keras.Input(shape=(10,))
>>> x = tf.keras.layers.Dense(10)(inputs)
>>> outputs = tf.keras.layers.Dense(1)(x)
>>> model = tf.keras.Model(inputs, outputs)
>>> # Activity regularization.
>>> len(model.losses)
0
>>> model.add_loss(tf.abs(tf.reduce_mean(x)))
>>> len(model.losses)
1

>>> inputs = tf.keras.Input(shape=(10,))
>>> d = tf.keras.layers.Dense(10, kernel_initializer='ones')
>>> x = d(inputs)
>>> outputs = tf.keras.layers.Dense(1)(x)
>>> model = tf.keras.Model(inputs, outputs)
>>> # Weight regularization.
>>> model.add_loss(lambda: tf.reduce_mean(d.kernel))
>>> model.losses
[<tf.Tensor: shape=(), dtype=float32, numpy=1.0>]

Returns: A list of tensors.

make_predict_function(force=False)

Creates a function that executes one step of inference.

This method can be overridden to support custom inference logic. This method is called by Model.predict and Model.predict_on_batch.

Typically, this method directly controls tf.function and tf.distribute.Strategy settings, and delegates the actual evaluation logic to Model.predict_step.

This function is cached the first time Model.predict or Model.predict_on_batch is called. The cache is cleared whenever Model.compile is called. You can skip the cache and generate again the function with force=True.

Parameters: force – Whether to regenerate the predict function and skip the cached function if available.
Returns: Function. The function created by this method should accept a tf.data.Iterator, and return the outputs of the Model.

make_test_function(force=False)

Creates a function that executes one step of evaluation.

This method can be overridden to support custom evaluation logic. This method is called by Model.evaluate and Model.test_on_batch.

Typically, this method directly controls tf.function and tf.distribute.Strategy settings, and delegates the actual evaluation logic to Model.test_step.

This function is cached the first time Model.evaluate or Model.test_on_batch is called. The cache is cleared whenever Model.compile is called. You can skip the cache and generate again the function with force=True.

Parameters: force – Whether to regenerate the test function and skip the cached function if available.
Returns: Function. The function created by this method should accept a tf.data.Iterator, and return a dict containing values that will be passed to tf.keras.Callbacks.on_test_batch_end.

make_train_function(force=False)

Creates a function that executes one step of training.

This method can be overridden to support custom training logic. This method is called by Model.fit and Model.train_on_batch.

Typically, this method directly controls tf.function and tf.distribute.Strategy settings, and delegates the actual training logic to Model.train_step.

This function is cached the first time Model.fit or Model.train_on_batch is called. The cache is cleared whenever Model.compile is called. You can skip the cache and generate again the function with force=True.

Parameters: force – Whether to regenerate the train function and skip the cached function if available.
Returns: Function. The function created by this method should accept a tf.data.Iterator, and return a dict containing values that will be passed to tf.keras.Callbacks.on_train_batch_end, such as {‘loss’: 0.2, ‘accuracy’: 0.7}.

property metrics

Returns the model’s metrics added using compile(), add_metric() APIs.

Note: Metrics passed to compile() are available only after a keras.Model has been trained/evaluated on actual data.

Examples:

>>> inputs = tf.keras.layers.Input(shape=(3,))
>>> outputs = tf.keras.layers.Dense(2)(inputs)
>>> model = tf.keras.models.Model(inputs=inputs, outputs=outputs)
>>> model.compile(optimizer="Adam", loss="mse", metrics=["mae"])
>>> [m.name for m in model.metrics]
[]

>>> x = np.random.random((2, 3))
>>> y = np.random.randint(0, 2, (2, 2))
>>> model.fit(x, y)
>>> [m.name for m in model.metrics]
['loss', 'mae']

>>> inputs = tf.keras.layers.Input(shape=(3,))
>>> d = tf.keras.layers.Dense(2, name='out')
>>> output_1 = d(inputs)
>>> output_2 = d(inputs)
>>> model = tf.keras.models.Model(
...    inputs=inputs, outputs=[output_1, output_2])
>>> model.add_metric(
...    tf.reduce_sum(output_2), name='mean', aggregation='mean')
>>> model.compile(optimizer="Adam", loss="mse", metrics=["mae", "acc"])
>>> model.fit(x, (y, y))
>>> [m.name for m in model.metrics]
['loss', 'out_loss', 'out_1_loss', 'out_mae', 'out_acc', 'out_1_mae',
'out_1_acc', 'mean']

property metrics_names

Returns the model’s display labels for all outputs.

Note: metrics_names are available only after a keras.Model has been trained/evaluated on actual data.

Examples:

>>> inputs = tf.keras.layers.Input(shape=(3,))
>>> outputs = tf.keras.layers.Dense(2)(inputs)
>>> model = tf.keras.models.Model(inputs=inputs, outputs=outputs)
>>> model.compile(optimizer="Adam", loss="mse", metrics=["mae"])
>>> model.metrics_names
[]

>>> x = np.random.random((2, 3))
>>> y = np.random.randint(0, 2, (2, 2))
>>> model.fit(x, y)
>>> model.metrics_names
['loss', 'mae']

>>> inputs = tf.keras.layers.Input(shape=(3,))
>>> d = tf.keras.layers.Dense(2, name='out')
>>> output_1 = d(inputs)
>>> output_2 = d(inputs)
>>> model = tf.keras.models.Model(
...    inputs=inputs, outputs=[output_1, output_2])
>>> model.compile(optimizer="Adam", loss="mse", metrics=["mae", "acc"])
>>> model.fit(x, (y, y))
>>> model.metrics_names
['loss', 'out_loss', 'out_1_loss', 'out_mae', 'out_acc', 'out_1_mae',
'out_1_acc']

property name: Name of the layer (string), set in the constructor.

property name_scope: Returns a tf.name_scope instance for this class.

property non_trainable_variables

Sequence of non-trainable variables owned by this module and its submodules.

Note: this method uses reflection to find variables on the current instance and submodules. For performance reasons you may wish to cache the result of calling this method if you don’t expect the return value to change.

Returns: A sequence of variables for the current module (sorted by attribute name) followed by variables from all submodules recursively (breadth first).

property non_trainable_weights

List of all non-trainable weights tracked by this layer.

Non-trainable weights are not updated during training. They are expected to be updated manually in call().

Returns: A list of non-trainable variables.

property outbound_nodes: Return Functional API nodes downstream of this layer.

property output

Retrieves the output tensor(s) of a layer.

Only applicable if the layer has exactly one output, i.e. if it is connected to one incoming layer.

Returns

Output tensor or list of output tensors.

Raises

AttributeError – if the layer is connected to more than one incoming layers.
RuntimeError – if called in Eager mode.

property output_mask

Retrieves the output mask tensor(s) of a layer.

Only applicable if the layer has exactly one inbound node, i.e. if it is connected to one incoming layer.

Returns

Output mask tensor (potentially None) or list of output mask tensors.

Raises

AttributeError – if the layer is connected to
more than one incoming layers. –

property output_shape

Retrieves the output shape(s) of a layer.

Only applicable if the layer has one output, or if all outputs have the same shape.

Returns

Output shape, as an integer shape tuple (or list of shape tuples, one tuple per output tensor).

Raises

AttributeError – if the layer has no defined output shape.
RuntimeError – if called in Eager mode.

predict(x, batch_size=None, verbose='auto', steps=None, callbacks=None, max_queue_size=10, workers=1, use_multiprocessing=False)

Generates output predictions for the input samples.

Computation is done in batches. This method is designed for batch processing of large numbers of inputs. It is not intended for use inside of loops that iterate over your data and process small numbers of inputs at a time.

For small numbers of inputs that fit in one batch, directly use __call__() for faster execution, e.g., model(x), or model(x, training=False) if you have layers such as tf.keras.layers.BatchNormalization that behave differently during inference. You may pair the individual model call with a tf.function for additional performance inside your inner loop. If you need access to numpy array values instead of tensors after your model call, you can use tensor.numpy() to get the numpy array value of an eager tensor.

Also, note the fact that test loss is not affected by regularization layers like noise and dropout.

Note: See [this FAQ entry]( https://keras.io/getting_started/faq/#whats-the-difference-between-model-methods-predict-and-call) for more details about the difference between Model methods predict() and __call__().

Parameters

x –
Input samples. It could be: - A Numpy array (or array-like), or a list of arrays

(in case the model has multiple inputs).
- A TensorFlow tensor, or a list of tensors (in case the model has multiple inputs).
- A tf.data dataset.
- A generator or keras.utils.Sequence instance.
A more detailed description of unpacking behavior for iterator types (Dataset, generator, Sequence) is given in the Unpacking behavior for iterator-like inputs section of Model.fit.
batch_size – Integer or None. Number of samples per batch. If unspecified, batch_size will default to 32. Do not specify the batch_size if your data is in the form of dataset, generators, or keras.utils.Sequence instances (since they generate batches).
verbose – “auto”, 0, 1, or 2. Verbosity mode. 0 = silent, 1 = progress bar, 2 = single line. “auto” defaults to 1 for most cases, and to 2 when used with ParameterServerStrategy. Note that the progress bar is not particularly useful when logged to a file, so verbose=2 is recommended when not running interactively (e.g. in a production environment).
steps – Total number of steps (batches of samples) before declaring the prediction round finished. Ignored with the default value of None. If x is a tf.data dataset and steps is None, predict() will run until the input dataset is exhausted.
callbacks – List of keras.callbacks.Callback instances. List of callbacks to apply during prediction. See [callbacks](/api_docs/python/tf/keras/callbacks).
max_queue_size – Integer. Used for generator or keras.utils.Sequence input only. Maximum size for the generator queue. If unspecified, max_queue_size will default to 10.
workers – Integer. Used for generator or keras.utils.Sequence input only. Maximum number of processes to spin up when using process-based threading. If unspecified, workers will default to 1.
use_multiprocessing – Boolean. Used for generator or keras.utils.Sequence input only. If True, use process-based threading. If unspecified, use_multiprocessing will default to False. Note that because this implementation relies on multiprocessing, you should not pass non-picklable arguments to the generator as they can’t be passed easily to children processes.

See the discussion of Unpacking behavior for iterator-like inputs for Model.fit. Note that Model.predict uses the same interpretation rules as Model.fit and Model.evaluate, so inputs must be unambiguous for all three methods.

Returns

Numpy array(s) of predictions.

Raises

RuntimeError – If model.predict is wrapped in a tf.function.
ValueError – In case of mismatch between the provided input data and the model’s expectations, or in case a stateful model receives a number of samples that is not a multiple of the batch size.

predict_generator(generator, steps=None, callbacks=None, max_queue_size=10, workers=1, use_multiprocessing=False, verbose=0)

Generates predictions for the input samples from a data generator.

DEPRECATED:: Model.predict now supports generators, so there is no longer any need to use this endpoint.

predict_on_batch(x)

Returns predictions for a single batch of samples.

Parameters

x –

Input data. It could be: - A Numpy array (or array-like), or a list of arrays (in case the

model has multiple inputs).

A TensorFlow tensor, or a list of tensors (in case the model has
multiple inputs).

Returns

Numpy array(s) of predictions.

Raises

RuntimeError – If model.predict_on_batch is wrapped in a tf.function.

predict_step(data)

The logic for one inference step.

This method can be overridden to support custom inference logic. This method is called by Model.make_predict_function.

This method should contain the mathematical logic for one step of inference. This typically includes the forward pass.

Configuration details for how this logic is run (e.g. tf.function and tf.distribute.Strategy settings), should be left to Model.make_predict_function, which can also be overridden.

Parameters: data – A nested structure of `Tensor`s.
Returns: The result of one inference step, typically the output of calling the Model on data.

reset_metrics()

Resets the state of all the metrics in the model.

Examples:

>>> inputs = tf.keras.layers.Input(shape=(3,))
>>> outputs = tf.keras.layers.Dense(2)(inputs)
>>> model = tf.keras.models.Model(inputs=inputs, outputs=outputs)
>>> model.compile(optimizer="Adam", loss="mse", metrics=["mae"])

>>> x = np.random.random((2, 3))
>>> y = np.random.randint(0, 2, (2, 2))
>>> _ = model.fit(x, y, verbose=0)
>>> assert all(float(m.result()) for m in model.metrics)

>>> model.reset_metrics()
>>> assert all(float(m.result()) == 0 for m in model.metrics)

property run_eagerly

Settable attribute indicating whether the model should run eagerly.

Running eagerly means that your model will be run step by step, like Python code. Your model might run slower, but it should become easier for you to debug it by stepping into individual layer calls.

By default, we will attempt to compile your model to a static graph to deliver the best execution performance.

Returns: Boolean, whether the model should run eagerly.

save(filepath, overwrite=True, include_optimizer=True, save_format=None, signatures=None, options=None, save_traces=True)

Saves the model to Tensorflow SavedModel or a single HDF5 file.

Please see tf.keras.models.save_model or the [Serialization and Saving guide]( https://keras.io/guides/serialization_and_saving/) for details.

Parameters

filepath – String, PathLike, path to SavedModel or H5 file to save the model.
overwrite – Whether to silently overwrite any existing file at the target location, or provide the user with a manual prompt.
include_optimizer – If True, save optimizer’s state together.
save_format – Either ‘tf’ or ‘h5’, indicating whether to save the model to Tensorflow SavedModel or HDF5. Defaults to ‘tf’ in TF 2.X, and ‘h5’ in TF 1.X.
signatures – Signatures to save with the SavedModel. Applicable to the ‘tf’ format only. Please see the signatures argument in tf.saved_model.save for details.
options – (only applies to SavedModel format) tf.saved_model.SaveOptions object that specifies options for saving to SavedModel.
save_traces – (only applies to SavedModel format) When enabled, the SavedModel will store the function traces for each layer. This can be disabled, so that only the configs of each layer are stored. Defaults to True. Disabling this will decrease serialization time and reduce file size, but it requires that all custom layers/models implement a get_config() method.

Example:

```python from keras.models import load_model

model.save(‘my_model.h5’) # creates a HDF5 file ‘my_model.h5’ del model # deletes the existing model

# returns a compiled model # identical to the previous one model = load_model(‘my_model.h5’) ```

save_spec(dynamic_batch=True)

Returns the tf.TensorSpec of call inputs as a tuple (args, kwargs).

This value is automatically defined after calling the model for the first time. Afterwards, you can use it when exporting the model for serving:

```python model = tf.keras.Model(…)

@tf.function def serve(*args, **kwargs):

outputs = model(*args, **kwargs) # Apply postprocessing steps, or add additional outputs. … return outputs

# arg_specs is [tf.TensorSpec(…), …]. kwarg_specs, in this # example, is an empty dict since functional models do not use keyword # arguments. arg_specs, kwarg_specs = model.save_spec()

model.save(path, signatures={

‘serving_default’: serve.get_concrete_function(*arg_specs,: **kwarg_specs)

})

param dynamic_batch: Whether to set the batch sizes of all the returned tf.TensorSpec to None. (Note that when defining functional or Sequential models with tf.keras.Input([…], batch_size=X), the batch size will always be preserved). Defaults to True.
returns: If the model inputs are defined, returns a tuple (args, kwargs). All elements in args and kwargs are tf.TensorSpec. If the model inputs are not defined, returns None. The model inputs are automatically set when calling the model, model.fit, model.evaluate or model.predict.

save_weights(filepath, overwrite=True, save_format=None, options=None)

Saves all layer weights.

Either saves in HDF5 or in TensorFlow format based on the save_format argument.

When saving in HDF5 format, the weight file has:

layer_names (attribute), a list of strings
(ordered names of model layers).
For every layer, a group named layer.name
- For every such layer group, a group attribute weight_names,
  a list of strings (ordered names of weights tensor of the layer).
- For every weight in the layer, a dataset
  storing the weight value, named after the weight tensor.

When saving in TensorFlow format, all objects referenced by the network are saved in the same format as tf.train.Checkpoint, including any Layer instances or Optimizer instances assigned to object attributes. For networks constructed from inputs and outputs using tf.keras.Model(inputs, outputs), Layer instances used by the network are tracked/saved automatically. For user-defined classes which inherit from tf.keras.Model, Layer instances must be assigned to object attributes, typically in the constructor. See the documentation of tf.train.Checkpoint and tf.keras.Model for details.

While the formats are the same, do not mix save_weights and tf.train.Checkpoint. Checkpoints saved by Model.save_weights should be loaded using Model.load_weights. Checkpoints saved using tf.train.Checkpoint.save should be restored using the corresponding tf.train.Checkpoint.restore. Prefer tf.train.Checkpoint over save_weights for training checkpoints.

The TensorFlow format matches objects and variables by starting at a root object, self for save_weights, and greedily matching attribute names. For Model.save this is the Model, and for Checkpoint.save this is the Checkpoint even if the Checkpoint has a model attached. This means saving a tf.keras.Model using save_weights and loading into a tf.train.Checkpoint with a Model attached (or vice versa) will not match the Model’s variables. See the [guide to training checkpoints]( https://www.tensorflow.org/guide/checkpoint) for details on the TensorFlow format.

Parameters

filepath – String or PathLike, path to the file to save the weights to. When saving in TensorFlow format, this is the prefix used for checkpoint files (multiple files are generated). Note that the ‘.h5’ suffix causes weights to be saved in HDF5 format.
overwrite – Whether to silently overwrite any existing file at the target location, or provide the user with a manual prompt.
save_format – Either ‘tf’ or ‘h5’. A filepath ending in ‘.h5’ or ‘.keras’ will default to HDF5 if save_format is None. Otherwise None defaults to ‘tf’.
options – Optional tf.train.CheckpointOptions object that specifies options for saving weights.

Raises

ImportError – If h5py is not available when attempting to save in HDF5 format.

set_weights(weights)

Sets the weights of the layer, from NumPy arrays.

The weights of a layer represent the state of the layer. This function sets the weight values from numpy arrays. The weight values should be passed in the order they are created by the layer. Note that the layer’s weights must be instantiated before calling this function, by calling the layer.

For example, a Dense layer returns a list of two values: the kernel matrix and the bias vector. These can be used to set the weights of another Dense layer:

>>> layer_a = tf.keras.layers.Dense(1,
...   kernel_initializer=tf.constant_initializer(1.))
>>> a_out = layer_a(tf.convert_to_tensor([[1., 2., 3.]]))
>>> layer_a.get_weights()
[array([[1.],
       [1.],
       [1.]], dtype=float32), array([0.], dtype=float32)]
>>> layer_b = tf.keras.layers.Dense(1,
...   kernel_initializer=tf.constant_initializer(2.))
>>> b_out = layer_b(tf.convert_to_tensor([[10., 20., 30.]]))
>>> layer_b.get_weights()
[array([[2.],
       [2.],
       [2.]], dtype=float32), array([0.], dtype=float32)]
>>> layer_b.set_weights(layer_a.get_weights())
>>> layer_b.get_weights()
[array([[1.],
       [1.],
       [1.]], dtype=float32), array([0.], dtype=float32)]

Parameters: weights – a list of NumPy arrays. The number of arrays and their shape must match number of the dimensions of the weights of the layer (i.e. it should match the output of get_weights).
Raises: ValueError – If the provided weights list does not match the layer’s specifications.

property state_updates

Deprecated, do NOT use!

Returns the updates from all layers that are stateful.

This is useful for separating training updates and state updates, e.g. when we need to update a layer’s internal state during prediction.

Returns: A list of update ops.

property submodules

Sequence of all sub-modules.

Submodules are modules which are properties of this module, or found as properties of modules which are properties of this module (and so on).

>>> a = tf.Module()
>>> b = tf.Module()
>>> c = tf.Module()
>>> a.b = b
>>> b.c = c
>>> list(a.submodules) == [b, c]
True
>>> list(b.submodules) == [c]
True
>>> list(c.submodules) == []
True

Returns: A sequence of all submodules.

summary(line_length=None, positions=None, print_fn=None, expand_nested=False, show_trainable=False, layer_range=None)

Prints a string summary of the network.

Parameters

line_length – Total length of printed lines (e.g. set this to adapt the display to different terminal window sizes).
positions – Relative or absolute positions of log elements in each line. If not provided, defaults to [.33, .55, .67, 1.].
print_fn – Print function to use. Defaults to print. It will be called on each line of the summary. You can set it to a custom function in order to capture the string summary.
expand_nested – Whether to expand the nested models. If not provided, defaults to False.
show_trainable – Whether to show if a layer is trainable. If not provided, defaults to False.
layer_range – a list or tuple of 2 strings, which is the starting layer name and ending layer name (both inclusive) indicating the range of layers to be printed in summary. It also accepts regex patterns instead of exact name. In such case, start predicate will be the first element it matches to layer_range[0] and the end predicate will be the last element it matches to layer_range[1]. By default None which considers all layers of model.

Raises

ValueError – if summary() is called before the model is built.

property supports_masking: Whether this layer supports computing a mask using compute_mask.

test_on_batch(x, y=None, sample_weight=None, reset_metrics=True, return_dict=False)

Test the model on a single batch of samples.

Parameters

x –
Input data. It could be: - A Numpy array (or array-like), or a list of arrays (in case the

model has multiple inputs).
- A TensorFlow tensor, or a list of tensors (in case the model has
  multiple inputs).
- A dict mapping input names to the corresponding array/tensors,
  if the model has named inputs.
y – Target data. Like the input data x, it could be either Numpy array(s) or TensorFlow tensor(s). It should be consistent with x (you cannot have Numpy inputs and tensor targets, or inversely).
sample_weight – Optional array of the same length as x, containing weights to apply to the model’s loss for each sample. In the case of temporal data, you can pass a 2D array with shape (samples, sequence_length), to apply a different weight to every timestep of every sample.
reset_metrics – If True, the metrics returned will be only for this batch. If False, the metrics will be statefully accumulated across batches.
return_dict – If True, loss and metric results are returned as a dict, with each key being the name of the metric. If False, they are returned as a list.

Returns

Scalar test loss (if the model has a single output and no metrics) or list of scalars (if the model has multiple outputs and/or metrics). The attribute model.metrics_names will give you the display labels for the scalar outputs.

Raises

RuntimeError – If model.test_on_batch is wrapped in a tf.function.

test_step(data)

The logic for one evaluation step.

This method can be overridden to support custom evaluation logic. This method is called by Model.make_test_function.

This function should contain the mathematical logic for one step of evaluation. This typically includes the forward pass, loss calculation, and metrics updates.

Configuration details for how this logic is run (e.g. tf.function and tf.distribute.Strategy settings), should be left to Model.make_test_function, which can also be overridden.

Parameters: data – A nested structure of `Tensor`s.
Returns: A dict containing values that will be passed to tf.keras.callbacks.CallbackList.on_train_batch_end. Typically, the values of the Model’s metrics are returned.

to_json(**kwargs)

Returns a JSON string containing the network configuration.

To load a network from a JSON save file, use keras.models.model_from_json(json_string, custom_objects={}).

Parameters: **kwargs – Additional keyword arguments to be passed to *json.dumps().
Returns: A JSON string.

to_yaml(**kwargs)

Returns a yaml string containing the network configuration.

Note: Since TF 2.6, this method is no longer supported and will raise a RuntimeError.

To load a network from a yaml save file, use keras.models.model_from_yaml(yaml_string, custom_objects={}).

custom_objects should be a dictionary mapping the names of custom losses / layers / etc to the corresponding functions / classes.

Parameters: **kwargs – Additional keyword arguments to be passed to yaml.dump().
Returns: A YAML string.
Raises: RuntimeError – announces that the method poses a security risk

train_on_batch(x, y=None, sample_weight=None, class_weight=None, reset_metrics=True, return_dict=False)

Runs a single gradient update on a single batch of data.

Parameters

x –
Input data. It could be: - A Numpy array (or array-like), or a list of arrays

(in case the model has multiple inputs).
- A TensorFlow tensor, or a list of tensors
  (in case the model has multiple inputs).
- A dict mapping input names to the corresponding array/tensors,
  if the model has named inputs.
y – Target data. Like the input data x, it could be either Numpy array(s) or TensorFlow tensor(s).
sample_weight – Optional array of the same length as x, containing weights to apply to the model’s loss for each sample. In the case of temporal data, you can pass a 2D array with shape (samples, sequence_length), to apply a different weight to every timestep of every sample.
class_weight – Optional dictionary mapping class indices (integers) to a weight (float) to apply to the model’s loss for the samples from this class during training. This can be useful to tell the model to “pay more attention” to samples from an under-represented class.
reset_metrics – If True, the metrics returned will be only for this batch. If False, the metrics will be statefully accumulated across batches.
return_dict – If True, loss and metric results are returned as a dict, with each key being the name of the metric. If False, they are returned as a list.

Returns

Scalar training loss (if the model has a single output and no metrics) or list of scalars (if the model has multiple outputs and/or metrics). The attribute model.metrics_names will give you the display labels for the scalar outputs.

Raises

RuntimeError – If model.train_on_batch is wrapped in a tf.function.

train_step(data)

The logic for one training step.

This method can be overridden to support custom training logic. For concrete examples of how to override this method see [Customizing what happens in fit]( https://www.tensorflow.org/guide/keras/customizing_what_happens_in_fit). This method is called by Model.make_train_function.

This method should contain the mathematical logic for one step of training. This typically includes the forward pass, loss calculation, backpropagation, and metric updates.

Configuration details for how this logic is run (e.g. tf.function and tf.distribute.Strategy settings), should be left to Model.make_train_function, which can also be overridden.

Parameters: data – A nested structure of `Tensor`s.
Returns: A dict containing values that will be passed to tf.keras.callbacks.CallbackList.on_train_batch_end. Typically, the values of the Model’s metrics are returned. Example: {‘loss’: 0.2, ‘accuracy’: 0.7}.

property trainable_variables

Sequence of trainable variables owned by this module and its submodules.

Note: this method uses reflection to find variables on the current instance and submodules. For performance reasons you may wish to cache the result of calling this method if you don’t expect the return value to change.

Returns: A sequence of variables for the current module (sorted by attribute name) followed by variables from all submodules recursively (breadth first).

property trainable_weights

List of all trainable weights tracked by this layer.

Trainable weights are updated via gradient descent during training.

Returns: A list of trainable variables.

property variable_dtype: Alias of Layer.dtype, the dtype of the weights.

property variables

Returns the list of all layer variables/weights.

Alias of self.weights.

Note: This will not track the weights of nested tf.Modules that are not themselves Keras layers.

Returns: A list of variables.

property weights

Returns the list of all layer variables/weights.

Note: This will not track the weights of nested tf.Modules that are not themselves Keras layers.

Returns: A list of variables.

classmethod with_name_scope(method)

Decorator to automatically enter the module name scope.

>>> class MyModule(tf.Module):
...   @tf.Module.with_name_scope
...   def __call__(self, x):
...     if not hasattr(self, 'w'):
...       self.w = tf.Variable(tf.random.normal([x.shape[1], 3]))
...     return tf.matmul(x, self.w)

Using the above module would produce `tf.Variable`s and `tf.Tensor`s whose names included the module name:

>>> mod = MyModule()
>>> mod(tf.ones([1, 2]))
<tf.Tensor: shape=(1, 3), dtype=float32, numpy=..., dtype=float32)>
>>> mod.w
<tf.Variable 'my_module/Variable:0' shape=(2, 3) dtype=float32,
numpy=..., dtype=float32)>

Parameters: method – The method to wrap.
Returns: The original method wrapped such that it enters the module’s name scope.