tf.estimator.LinearClassifier

Class LinearClassifier

Inherits From: Estimator

Defined in tensorflow/python/estimator/canned/linear.py.

Linear classifier model.

Train a linear model to classify instances into one of multiple possible classes. When number of possible classes is 2, this is binary classification.

Example:

categorical_column_a = categorical_column_with_hash_bucket(...)
categorical_column_b = categorical_column_with_hash_bucket(...)

categorical_feature_a_x_categorical_feature_b = crossed_column(...)

# Estimator using the default optimizer.
estimator = LinearClassifier(
    feature_columns=[categorical_column_a,
                     categorical_feature_a_x_categorical_feature_b])

# Or estimator using the FTRL optimizer with regularization.
estimator = LinearClassifier(
    feature_columns=[categorical_column_a,
                     categorical_feature_a_x_categorical_feature_b],
    optimizer=tf.train.FtrlOptimizer(
      learning_rate=0.1,
      l1_regularization_strength=0.001
    ))

# Or estimator with warm-starting from a previous checkpoint.
estimator = LinearClassifier(
    feature_columns=[categorical_column_a,
                     categorical_feature_a_x_categorical_feature_b],
    warm_start_from="/path/to/checkpoint/dir")

# Input builders
def input_fn_train: # returns x, y (where y represents label's class index).
  ...
def input_fn_eval: # returns x, y (where y represents label's class index).
  ...
estimator.train(input_fn=input_fn_train)
estimator.evaluate(input_fn=input_fn_eval)
estimator.predict(input_fn=input_fn_predict)

Input of train and evaluate should have following features, otherwise there will be a KeyError:

• if weight_column is not None, a feature with key=weight_column whose value is a Tensor.
• for each column in feature_columns:
• if column is a SparseColumn, a feature with key=column.name whose value is a SparseTensor.
• if column is a WeightedSparseColumn, two features: the first with key the id column name, the second with key the weight column name. Both features' value must be a SparseTensor.
• if column is a RealValuedColumn, a feature with key=column.name whose value is a Tensor.

Loss is calculated by using softmax cross entropy.

Eager Compatibility

Estimators are not compatible with eager execution.

Properties

config

model_dir

model_fn

Returns the model_fn which is bound to self.params.

Returns:

The model_fn with following signature: def model_fn(features, labels, mode, config)

params

Methods

__init__

__init__(
    feature_columns,
    model_dir=None,
    n_classes=2,
    weight_column=None,
    label_vocabulary=None,
    optimizer='Ftrl',
    config=None,
    partitioner=None,
    warm_start_from=None,
    loss_reduction=losses.Reduction.SUM
)

Construct a LinearClassifier estimator object.

Args:

• feature_columns: An iterable containing all the feature columns used by the model. All items in the set should be instances of classes derived from FeatureColumn.
• model_dir: Directory to save model parameters, graph and etc. This can also be used to load checkpoints from the directory into a estimator to continue training a previously saved model.
• n_classes: number of label classes. Default is binary classification. Note that class labels are integers representing the class index (i.e. values from 0 to n_classes-1). For arbitrary label values (e.g. string labels), convert to class indices first.
• weight_column: A string or a _NumericColumn created by tf.feature_column.numeric_column defining feature column representing weights. It is used to down weight or boost examples during training. It will be multiplied by the loss of the example. If it is a string, it is used as a key to fetch weight tensor from the features. If it is a _NumericColumn, raw tensor is fetched by key weight_column.key, then weight_column.normalizer_fn is applied on it to get weight tensor.
• label_vocabulary: A list of strings represents possible label values. If given, labels must be string type and have any value in label_vocabulary. If it is not given, that means labels are already encoded as integer or float within [0, 1] for n_classes=2 and encoded as integer values in {0, 1,..., n_classes-1} for n_classes>2 . Also there will be errors if vocabulary is not provided and labels are string.
• optimizer: An instance of tf.Optimizer used to train the model. Defaults to FTRL optimizer.
• config: RunConfig object to configure the runtime settings.
• partitioner: Optional. Partitioner for input layer.
• warm_start_from: A string filepath to a checkpoint to warm-start from, or a WarmStartSettings object to fully configure warm-starting. If the string filepath is provided instead of a WarmStartSettings, then all weights and biases are warm-started, and it is assumed that vocabularies and Tensor names are unchanged.
• loss_reduction: One of tf.losses.Reduction except NONE. Describes how to reduce training loss over batch. Defaults to SUM.

Returns:

A LinearClassifier estimator.

Raises:

• ValueError: if n_classes < 2.

evaluate

evaluate(
    input_fn,
    steps=None,
    hooks=None,
    checkpoint_path=None,
    name=None
)

Evaluates the model given evaluation data input_fn.

For each step, calls input_fn, which returns one batch of data. Evaluates until: - steps batches are processed, or - input_fn raises an end-of-input exception (OutOfRangeError or StopIteration).

Args:

• input_fn: A function that constructs the input data for evaluation. See Premade Estimators for more information. The function should construct and return one of the following:

  • A 'tf.data.Dataset' object: Outputs of Dataset object must be a tuple (features, labels) with same constraints as below.
  • A tuple (features, labels): Where features is a Tensor or a dictionary of string feature name to Tensor and labels is a Tensor or a dictionary of string label name to Tensor. Both features and labels are consumed by model_fn. They should satisfy the expectation of model_fn from inputs.

• steps: Number of steps for which to evaluate model. If None, evaluates until input_fn raises an end-of-input exception.

• hooks: List of SessionRunHook subclass instances. Used for callbacks inside the evaluation call.
• checkpoint_path: Path of a specific checkpoint to evaluate. If None, the latest checkpoint in model_dir is used.
• name: Name of the evaluation if user needs to run multiple evaluations on different data sets, such as on training data vs test data. Metrics for different evaluations are saved in separate folders, and appear separately in tensorboard.

Returns:

A dict containing the evaluation metrics specified in model_fn keyed by name, as well as an entry global_step which contains the value of the global step for which this evaluation was performed.

Raises:

• ValueError: If steps <= 0.
• ValueError: If no model has been trained, namely model_dir, or the given checkpoint_path is empty.

export_savedmodel

export_savedmodel(
    export_dir_base,
    serving_input_receiver_fn,
    assets_extra=None,
    as_text=False,
    checkpoint_path=None,
    strip_default_attrs=False
)

Exports inference graph as a SavedModel into given dir.

For a detailed guide, see Using SavedModel with Estimators.

This method builds a new graph by first calling the serving_input_receiver_fn to obtain feature Tensors, and then calling this Estimator's model_fn to generate the model graph based on those features. It restores the given checkpoint (or, lacking that, the most recent checkpoint) into this graph in a fresh session. Finally it creates a timestamped export directory below the given export_dir_base, and writes a SavedModel into it containing a single MetaGraphDef saved from this session.

The exported MetaGraphDef will provide one SignatureDef for each element of the export_outputs dict returned from the model_fn, named using the same keys. One of these keys is always signature_constants.DEFAULT_SERVING_SIGNATURE_DEF_KEY, indicating which signature will be served when a serving request does not specify one. For each signature, the outputs are provided by the corresponding ExportOutputs, and the inputs are always the input receivers provided by the serving_input_receiver_fn.

Extra assets may be written into the SavedModel via the assets_extra argument. This should be a dict, where each key gives a destination path (including the filename) relative to the assets.extra directory. The corresponding value gives the full path of the source file to be copied. For example, the simple case of copying a single file without renaming it is specified as {'my_asset_file.txt': '/path/to/my_asset_file.txt'}.

Args:

• export_dir_base: A string containing a directory in which to create timestamped subdirectories containing exported SavedModels.
• serving_input_receiver_fn: A function that takes no argument and returns a ServingInputReceiver or TensorServingInputReceiver.
• assets_extra: A dict specifying how to populate the assets.extra directory within the exported SavedModel, or None if no extra assets are needed.
• as_text: whether to write the SavedModel proto in text format.
• checkpoint_path: The checkpoint path to export. If None (the default), the most recent checkpoint found within the model directory is chosen.
• strip_default_attrs: Boolean. If True, default-valued attributes will be removed from the NodeDefs. For a detailed guide, see Stripping Default-Valued Attributes.

Returns:

The string path to the exported directory.

Raises:

• ValueError: if no serving_input_receiver_fn is provided, no export_outputs are provided, or no checkpoint can be found.

get_variable_names

get_variable_names()

Returns list of all variable names in this model.

Returns:

List of names.

Raises:

• ValueError: If the Estimator has not produced a checkpoint yet.

get_variable_value

get_variable_value(name)

Returns value of the variable given by name.

Args:

• name: string or a list of string, name of the tensor.

Returns:

Numpy array - value of the tensor.

Raises:

• ValueError: If the Estimator has not produced a checkpoint yet.

latest_checkpoint

latest_checkpoint()

Finds the filename of latest saved checkpoint file in model_dir.

Returns:

The full path to the latest checkpoint or None if no checkpoint was found.

predict

predict(
    input_fn,
    predict_keys=None,
    hooks=None,
    checkpoint_path=None,
    yield_single_examples=True
)

Yields predictions for given features.

Args:

• input_fn: A function that constructs the features. Prediction continues until input_fn raises an end-of-input exception (OutOfRangeError or StopIteration). See Premade Estimators for more information. The function should construct and return one of the following:

  • A 'tf.data.Dataset' object: Outputs of Dataset object must have same constraints as below.
  • features: A Tensor or a dictionary of string feature name to Tensor. features are consumed by model_fn. They should satisfy the expectation of model_fn from inputs.
  • A tuple, in which case the first item is extracted as features.

• predict_keys: list of str, name of the keys to predict. It is used if the EstimatorSpec.predictions is a dict. If predict_keys is used then rest of the predictions will be filtered from the dictionary. If None, returns all.

• hooks: List of SessionRunHook subclass instances. Used for callbacks inside the prediction call.
• checkpoint_path: Path of a specific checkpoint to predict. If None, the latest checkpoint in model_dir is used.
• yield_single_examples: If False, yield the whole batch as returned by the model_fn instead of decomposing the batch into individual elements. This is useful if model_fn returns some tensors whose first dimension is not equal to the batch size.

Yields:

Evaluated values of predictions tensors.

Raises:

• ValueError: Could not find a trained model in model_dir.
• ValueError: If batch length of predictions is not the same and yield_single_examples is True.
• ValueError: If there is a conflict between predict_keys and predictions. For example if predict_keys is not None but EstimatorSpec.predictions is not a dict.

train

train(
    input_fn,
    hooks=None,
    steps=None,
    max_steps=None,
    saving_listeners=None
)

Trains a model given training data input_fn.

Args:

• input_fn: A function that provides input data for training as minibatches. See Premade Estimators for more information. The function should construct and return one of the following:

  • A 'tf.data.Dataset' object: Outputs of Dataset object must be a tuple (features, labels) with same constraints as below.
  • A tuple (features, labels): Where features is a Tensor or a dictionary of string feature name to Tensor and labels is a Tensor or a dictionary of string label name to Tensor. Both features and labels are consumed by model_fn. They should satisfy the expectation of model_fn from inputs.

• hooks: List of SessionRunHook subclass instances. Used for callbacks inside the training loop.

• steps: Number of steps for which to train model. If None, train forever or train until input_fn generates the OutOfRange error or StopIteration exception. 'steps' works incrementally. If you call two times train(steps=10) then training occurs in total 20 steps. If OutOfRange or StopIteration occurs in the middle, training stops before 20 steps. If you don't want to have incremental behavior please set max_steps instead. If set, max_steps must be None.
• max_steps: Number of total steps for which to train model. If None, train forever or train until input_fn generates the OutOfRange error or StopIteration exception. If set, steps must be None. If OutOfRange or StopIteration occurs in the middle, training stops before max_steps steps. Two calls to train(steps=100) means 200 training iterations. On the other hand, two calls to train(max_steps=100) means that the second call will not do any iteration since first call did all 100 steps.
• saving_listeners: list of CheckpointSaverListener objects. Used for callbacks that run immediately before or after checkpoint savings.

Returns:

self, for chaining.

Raises:

• ValueError: If both steps and max_steps are not None.
• ValueError: If either steps or max_steps is <= 0.