keras.Model

2022-06-08 17:23:49 浏览数 (1)

目录

Class Model

Used in the guide:

Used in the tutorials:

__init__

Properties

layers

metrics_names

run_eagerly

sample_weights

state_updates

stateful

Methods

compile

evaluate

evaluate_generator

fit

fit_generator

get_layer

load_weights

predict

predict_generator

predict_on_batch

reset_metrics

reset_states

save

save_weights

summary

test_on_batch

to_json

to_yaml

train_on_batch

Class Model

Model groups layers into an object with training and inference features.

Aliases: tf.compat.v1.keras.Model, tf.compat.v1.keras.models.Model, tf.compat.v2.keras.Model, tf.compat.v2.keras.models.Model, tf.keras.models.Model

Used in the guide:

  • The Keras functional API in TensorFlow
  • Train and evaluate with Keras
  • Writing custom layers and models with Keras
  • Save and serialize models with Keras
  • Recurrent Neural Networks (RNN) with Keras

Used in the tutorials:

  • Pix2Pix
  • Image segmentation
  • DeepDream
  • Neural style transfer
  • Load a pandas.DataFrame

There are two ways to instantiate a Model:

1 - With the "functional API", where you start from Input, you chain layer calls to specify the model's forward pass, and finally you create your model from inputs and outputs:

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import tensorflow as tf

inputs = tf.keras.Input(shape=(3,))
x = tf.keras.layers.Dense(4, activation=tf.nn.relu)(inputs)
outputs = tf.keras.layers.Dense(5, activation=tf.nn.softmax)(x)
model = tf.keras.Model(inputs=inputs, outputs=outputs)

2 - By subclassing the Model class: in that case, you should define your layers in __init__ and you should implement the model's forward pass in call.

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import tensorflow as tf

class MyModel(tf.keras.Model):

  def __init__(self):
    super(MyModel, self).__init__()
    self.dense1 = tf.keras.layers.Dense(4, activation=tf.nn.relu)
    self.dense2 = tf.keras.layers.Dense(5, activation=tf.nn.softmax)

  def call(self, inputs):
    x = self.dense1(inputs)
    return self.dense2(x)

model = MyModel()

If you subclass Model, you can optionally have a training argument (boolean) in call, which you can use to specify a different behavior in training and inference:

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import tensorflow as tf

class MyModel(tf.keras.Model):

  def __init__(self):
    super(MyModel, self).__init__()
    self.dense1 = tf.keras.layers.Dense(4, activation=tf.nn.relu)
    self.dense2 = tf.keras.layers.Dense(5, activation=tf.nn.softmax)
    self.dropout = tf.keras.layers.Dropout(0.5)

  def call(self, inputs, training=False):
    x = self.dense1(inputs)
    if training:
      x = self.dropout(x, training=training)
    return self.dense2(x)

model = MyModel()

__init__

View source

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__init__(
    *args,
    **kwargs
)

Properties

layers

metrics_names

Returns the model's display labels for all outputs.

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.

sample_weights

state_updates

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.

stateful

Methods

compile

View source

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compile(
    optimizer='rmsprop',
    loss=None,
    metrics=None,
    loss_weights=None,
    sample_weight_mode=None,
    weighted_metrics=None,
    target_tensors=None,
    distribute=None,
    **kwargs
)

Configures the model for training.

Arguments:

  • optimizer: String (name of optimizer) or optimizer instance. See tf.keras.optimizers.
  • loss: String (name of objective function), objective function or tf.losses.Loss instance. See tf.losses. 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.
  • metrics: List of metrics to be evaluated by the model during training and testing. Typically you will use metrics=['accuracy']. 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 (len = len(outputs)) of lists of metrics such as metrics=[['accuracy'], ['accuracy', 'mse']] or metrics=['accuracy', ['accuracy', 'mse']].
  • 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 tensor, it is expected to map output names (strings) to scalar coefficients.
  • sample_weight_mode: If you need to do timestep-wise sample weighting (2D weights), set this to "temporal". None defaults to sample-wise weights (1D). If the model has multiple outputs, you can use a different sample_weight_mode on each output by passing a dictionary or a list of modes.
  • weighted_metrics: List of metrics to be evaluated and weighted by sample_weight or class_weight during training and testing.
  • target_tensors: By default, Keras will create placeholders for the model's target, which will be fed with the target data during training. If instead you would like to use your own target tensors (in turn, Keras will not expect external Numpy data for these targets at training time), you can specify them via the target_tensors argument. It can be a single tensor (for a single-output model), a list of tensors, or a dict mapping output names to target tensors.
  • distribute: NOT SUPPORTED IN TF 2.0, please create and compile the model under distribution strategy scope instead of passing it to compile.
  • **kwargs: Any additional arguments.

Raises:

  • ValueError: In case of invalid arguments for optimizer, loss, metrics or sample_weight_mode.

evaluate

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evaluate(
    x=None,
    y=None,
    batch_size=None,
    verbose=1,
    sample_weight=None,
    steps=None,
    callbacks=None,
    max_queue_size=10,
    workers=1,
    use_multiprocessing=False
)

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

Computation is done in batches.

Arguments:

  • 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.
    • A generator or keras.utils.Sequence instance.
  • 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 gradient update. If unspecified, batch_size will default to 32. Do not specify the batch_size is your data is in the form of symbolic tensors, dataset, generators, or keras.utils.Sequence instances (since they generate batches).
  • verbose: 0 or 1. Verbosity mode. 0 = silent, 1 = progress bar.
  • 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. In this case you should make sure to specify sample_weight_mode="temporal" in compile(). 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.
  • 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. If 0, will execute the generator on the main thread.
  • 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.

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:

  • ValueError: in case of invalid arguments.

evaluate_generator

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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.

The generator should return the same kind of data as accepted by test_on_batch.

Arguments:

  • generator: Generator yielding tuples (inputs, targets) or (inputs, targets, sample_weights) or an instance of keras.utils.Sequence object in order to avoid duplicate data when using multiprocessing.
  • steps: Total number of steps (batches of samples) to yield from generator before stopping. Optional for Sequence: if unspecified, will use the len(generator) as a number of steps.
  • callbacks: List of keras.callbacks.Callback instances. List of callbacks to apply during evaluation. See callbacks.
  • max_queue_size: maximum size for the generator queue
  • workers: Integer. Maximum number of processes to spin up when using process-based threading. If unspecified, workers will default to 1. If 0, will execute the generator on the main thread.
  • use_multiprocessing: Boolean. 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.
  • verbose: Verbosity mode, 0 or 1.

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:

  • ValueError: in case of invalid arguments.

Raises:

  • ValueError: In case the generator yields data in an invalid format.

fit

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fit(
    x=None,
    y=None,
    batch_size=None,
    epochs=1,
    verbose=1,
    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_freq=1,
    max_queue_size=10,
    workers=1,
    use_multiprocessing=False,
    **kwargs
)

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

Arguments:

  • 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).
  • 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 symbolic tensors, 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. 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: 0, 1, or 2. Verbosity mode. 0 = silent, 1 = progress bar, 2 = one line per epoch. 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.
  • 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.
  • 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. validation_data will override validation_split. validation_data could be:
    • tuple (x_val, y_val) of Numpy arrays or tensors
    • tuple (x_val, y_val, val_sample_weights) of Numpy arrays
    • dataset For the first two cases, batch_size must be provided. For the last case, validation_steps must be provided.
  • shuffle: Boolean (whether to shuffle the training data before each epoch) or str (for 'batch'). '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. In this case you should make sure to specify sample_weight_mode="temporal" in compile(). 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.
  • 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. This argument is not supported with array inputs.
  • 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_data is a tf.data dataset and 'validation_steps' is None, validation will run until the validation_data dataset is exhausted.
  • 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. If 0, will execute the generator on the main thread.
  • 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.
  • **kwargs: Used for backwards compatibility.

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: If the model was never compiled.
  • ValueError: In case of mismatch between the provided input data and what the model expects.

fit_generator

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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.

The generator is run in parallel to the model, for efficiency. For instance, this allows you to do real-time data augmentation on images on CPU in parallel to training your model on GPU.

The use of keras.utils.Sequence guarantees the ordering and guarantees the single use of every input per epoch when using use_multiprocessing=True.

Arguments:

  • generator: A generator or an instance of Sequence (keras.utils.Sequence) object in order to avoid duplicate data when using multiprocessing. The output of the generator must be either
    • a tuple (inputs, targets)
    • a tuple (inputs, targets, sample_weights). This tuple (a single output of the generator) makes a single batch. Therefore, all arrays in this tuple must have the same length (equal to the size of this batch). Different batches may have different sizes. For example, the last batch of the epoch is commonly smaller than the others, if the size of the dataset is not divisible by the batch size. The generator is expected to loop over its data indefinitely. An epoch finishes when steps_per_epoch batches have been seen by the model.
  • steps_per_epoch: Total number of steps (batches of samples) to yield from generator before declaring one epoch finished and starting the next epoch. It should typically be equal to the number of samples of your dataset divided by the batch size. Optional for Sequence: if unspecified, will use the len(generator) as a number of steps.
  • epochs: Integer, total number of iterations on the data.
  • verbose: Verbosity mode, 0, 1, or 2.
  • callbacks: List of callbacks to be called during training.
  • validation_data: This can be either
    • a generator for the validation data
    • a tuple (inputs, targets)
    • a tuple (inputs, targets, sample_weights).
  • validation_steps: Only relevant if validation_data is a generator. Total number of steps (batches of samples) to yield from generator before stopping. Optional for Sequence: if unspecified, will use the len(validation_data) as a number of steps.
  • 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.
  • class_weight: Dictionary mapping class indices to a weight for the class.
  • max_queue_size: Integer. Maximum size for the generator queue. If unspecified, max_queue_size will default to 10.
  • workers: Integer. Maximum number of processes to spin up when using process-based threading. If unspecified, workers will default to 1. If 0, will execute the generator on the main thread.
  • use_multiprocessing: Boolean. 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.
  • shuffle: Boolean. Whether to shuffle the order of the batches at the beginning of each epoch. Only used with instances of Sequence (keras.utils.Sequence). Has no effect when steps_per_epoch is not None.
  • initial_epoch: Epoch at which to start training (useful for resuming a previous training run)

Returns:

  • A History object.

Example:

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    def generate_arrays_from_file(path):
        while 1:
            f = open(path)
            for line in f:
                # create numpy arrays of input data
                # and labels, from each line in the file
                x1, x2, y = process_line(line)
                yield ({'input_1': x1, 'input_2': x2}, {'output': y})
            f.close()

    model.fit_generator(generate_arrays_from_file('/my_file.txt'),
                        steps_per_epoch=10000, epochs=10)

Raises:

  • ValueError: In case the generator yields data in an invalid format.

get_layer

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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).

Arguments:

  • name: String, name of layer.
  • index: Integer, index of layer.

Returns:

  • A layer instance.

Raises:

  • ValueError: In case of invalid layer name or index.

load_weights

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load_weights(
    filepath,
    by_name=False
)

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

predict

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predict(
    x,
    batch_size=None,
    verbose=0,
    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.

Arguments:

  • 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.
  • 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 is your data is in the form of symbolic tensors, dataset, generators, or keras.utils.Sequence instances (since they generate batches).
  • verbose: Verbosity mode, 0 or 1.
  • 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.
  • 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. If 0, will execute the generator on the main thread.
  • 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.

Returns:

  • Numpy array(s) of predictions.

Raises:

  • 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

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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.

The generator should return the same kind of data as accepted by predict_on_batch.

Arguments:

  • generator: Generator yielding batches of input samples or an instance of keras.utils.Sequence object in order to avoid duplicate data when using multiprocessing.
  • steps: Total number of steps (batches of samples) to yield from generator before stopping. Optional for Sequence: if unspecified, will use the len(generator) as a number of steps.
  • callbacks: List of keras.callbacks.Callback instances. List of callbacks to apply during prediction. See callbacks.
  • max_queue_size: Maximum size for the generator queue.
  • workers: Integer. Maximum number of processes to spin up when using process-based threading. If unspecified, workers will default to 1. If 0, will execute the generator on the main thread.
  • use_multiprocessing: Boolean. 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.
  • verbose: verbosity mode, 0 or 1.

Returns:

  • Numpy array(s) of predictions.

Raises:

  • ValueError: In case the generator yields data in an invalid format.

predict_on_batch

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predict_on_batch(x)

Returns predictions for a single batch of samples.

Arguments:

  • 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 tf.data dataset.

Returns:

  • Numpy array(s) of predictions.

Raises:

  • ValueError: In case of mismatch between given number of inputs and expectations of the model.

reset_metrics

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reset_metrics()

Resets the state of metrics.

reset_states

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reset_states()

save

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

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

The savefile includes:

  • The model architecture, allowing to re-instantiate the model.
  • The model weights.
  • The state of the optimizer, allowing to resume training exactly where you left off.

This allows you to save the entirety of the state of a model in a single file.

Saved models can be reinstantiated via keras.models.load_model. The model returned by load_model is a compiled model ready to be used (unless the saved model was never compiled in the first place).

Arguments:

  • filepath: String, 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. The default is currently 'h5', but will switch to 'tf' in TensorFlow 2.0. The 'tf' option is currently disabled (use tf.keras.experimental.export_saved_model instead).
  • 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: Optional tf.saved_model.SaveOptions object that specifies options for saving to SavedModel.

Example:

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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_weights

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save_weights(
    filepath,
    overwrite=True,
    save_format=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 for details on the TensorFlow format.

Arguments:

  • filepath: String, 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'.

Raises:

  • ImportError: If h5py is not available when attempting to save in HDF5 format.
  • ValueError: For invalid/unknown format arguments.

summary

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summary(
    line_length=None,
    positions=None,
    print_fn=None
)

Prints a string summary of the network.

Arguments:

  • 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.

Raises:

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

test_on_batch

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test_on_batch(
    x,
    y=None,
    sample_weight=None,
    reset_metrics=True
)

Test the model on a single batch of samples.

Arguments:

  • 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.
  • 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 y should not be specified (since targets will be obtained from the iterator).
  • 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. In this case you should make sure to specify sample_weight_mode="temporal" in compile(). This argument is not supported when x is a dataset.
  • reset_metrics: If True, the metrics returned will be only for this batch. If False, the metrics will be statefully accumulated across batches.

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:

  • ValueError: In case of invalid user-provided arguments.

to_json

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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={}).

Arguments:

  • **kwargs: Additional keyword arguments to be passed to json.dumps().

Returns:

  • A JSON string.

to_yaml

View source

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to_yaml(**kwargs)

Returns a yaml string containing the network configuration.

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.

Arguments:

  • **kwargs: Additional keyword arguments to be passed to yaml.dump().

Returns:

  • A YAML string.

Raises:

  • ImportError: if yaml module is not found.

train_on_batch

View source

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

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

Arguments:

  • 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.
  • 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, y should not be specified (since targets will be obtained from the iterator).
  • 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. In this case you should make sure to specify sample_weight_mode="temporal" in compile(). This argument is not supported when x is a dataset.
  • 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.

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:

  • ValueError: In case of invalid user-provided arguments.
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