Python head._binary_logistic_head_with_sigmoid_cross_entropy_loss函数代码示例

  def testTrainEvaluateInferDoesNotThrowErrorWithDnnInput(self):
    head_fn = head_lib._binary_logistic_head_with_sigmoid_cross_entropy_loss(
        loss_reduction=losses.Reduction.SUM_OVER_NONZERO_WEIGHTS)

    learner_config = learner_pb2.LearnerConfig()
    learner_config.num_classes = 2
    learner_config.constraints.max_tree_depth = 3
    model_dir = tempfile.mkdtemp()
    config = run_config.RunConfig()

    est = estimator.CoreDNNBoostedTreeCombinedEstimator(
        head=head_fn,
        dnn_hidden_units=[1],
        dnn_feature_columns=[core_feature_column.numeric_column("x")],
        tree_learner_config=learner_config,
        num_trees=1,
        tree_examples_per_layer=3,
        model_dir=model_dir,
        config=config,
        dnn_steps_to_train=10,
        dnn_input_layer_to_tree=True,
        tree_feature_columns=[])

    # Train for a few steps.
    est.train(input_fn=_train_input_fn, steps=1000)
    res = est.evaluate(input_fn=_eval_input_fn, steps=1)
    self.assertLess(0.5, res["auc"])
    est.predict(input_fn=_eval_input_fn)

  def testFitAndEvaluateDontThrowExceptionWithCore(self):
    learner_config = learner_pb2.LearnerConfig()
    learner_config.num_classes = 2
    learner_config.constraints.max_tree_depth = 1
    model_dir = tempfile.mkdtemp()
    config = run_config.RunConfig()

    # Use core head
    head_fn = head_lib._binary_logistic_head_with_sigmoid_cross_entropy_loss(
        loss_reduction=losses.Reduction.SUM_OVER_BATCH_SIZE)

    classifier = estimator.DNNBoostedTreeCombinedEstimator(
        head=head_fn,
        dnn_hidden_units=[1],
        # Use core feature columns
        dnn_feature_columns=[core_feature_column.numeric_column("x")],
        tree_learner_config=learner_config,
        num_trees=1,
        tree_examples_per_layer=3,
        model_dir=model_dir,
        config=config,
        dnn_steps_to_train=10,
        dnn_input_layer_to_tree=True,
        tree_feature_columns=[],
        use_core_versions=True)

    classifier.fit(input_fn=_train_input_fn, steps=15)
    classifier.evaluate(input_fn=_eval_input_fn, steps=1)

  def testRankingDontThrowExceptionForForEstimator(self):
    learner_config = learner_pb2.LearnerConfig()
    learner_config.num_classes = 2
    learner_config.constraints.max_tree_depth = 1
    model_dir = tempfile.mkdtemp()
    config = run_config.RunConfig()

    head_fn = head_lib._binary_logistic_head_with_sigmoid_cross_entropy_loss(
        loss_reduction=losses.Reduction.SUM_OVER_NONZERO_WEIGHTS)

    est = estimator.CoreGradientBoostedDecisionTreeRanker(
        head=head_fn,
        learner_config=learner_config,
        num_trees=1,
        examples_per_layer=3,
        model_dir=model_dir,
        config=config,
        feature_columns=[
            core_feature_column.numeric_column("f1"),
            core_feature_column.numeric_column("f2")
        ],
        ranking_model_pair_keys=("a", "b"))

    # Train for a few steps.
    est.train(input_fn=_ranking_train_input_fn, steps=1000)
    est.evaluate(input_fn=_ranking_train_input_fn, steps=1)
    est.predict(input_fn=_infer_ranking_train_input_fn)

  def __init__(self,
               hidden_units,
               feature_columns,
               model_dir=None,
               n_classes=2,
               weight_feature_key=None,
               optimizer='Adagrad',
               activation_fn=nn.relu,
               dropout=None,
               input_layer_partitioner=None,
               config=None):
    """Initializes a `DNNClassifier` instance.

    Args:
      hidden_units: Iterable of number hidden units per layer. All layers are
        fully connected. Ex. `[64, 32]` means first layer has 64 nodes and
        second one has 32.
      feature_columns: An iterable containing all the feature columns used by
        the model. All items in the set should be instances of classes derived
        from `_FeatureColumn`.
      model_dir: Directory to save model parameters, graph and etc. This can
        also be used to load checkpoints from the directory into a estimator to
        continue training a previously saved model.
      n_classes: Number of label classes. Defaults to 2, namely binary
        classification. Must be > 1.
      weight_feature_key: A string defining feature column name representing
        weights. It is used to down weight or boost examples during training. It
        will be multiplied by the loss of the example.
      optimizer: An instance of `tf.Optimizer` used to train the model. If
        `None`, will use an Adagrad optimizer.
      activation_fn: Activation function applied to each layer. If `None`, will
        use `tf.nn.relu`.
      dropout: When not `None`, the probability we will drop out a given
        coordinate.
      input_layer_partitioner: Optional. Partitioner for input layer. Defaults
        to `min_max_variable_partitioner` with `min_slice_size` 64 << 20.
      config: `RunConfig` object to configure the runtime settings.
    """
    if n_classes == 2:
      head = head_lib._binary_logistic_head_with_sigmoid_cross_entropy_loss(  # pylint: disable=protected-access
          weight_feature_key=weight_feature_key)
    else:
      head = head_lib._multi_class_head_with_softmax_cross_entropy_loss(  # pylint: disable=protected-access
          n_classes, weight_feature_key=weight_feature_key)
    def _model_fn(features, labels, mode, config):
      return _dnn_model_fn(
          features=features,
          labels=labels,
          mode=mode,
          head=head,
          hidden_units=hidden_units,
          feature_columns=tuple(feature_columns or []),
          optimizer=optimizer,
          activation_fn=activation_fn,
          dropout=dropout,
          input_layer_partitioner=input_layer_partitioner,
          config=config)
    super(DNNClassifier, self).__init__(
        model_fn=_model_fn, model_dir=model_dir, config=config)

  def __init__(self,
               model_dir=None,
               n_classes=2,
               weight_column=None,
               label_vocabulary=None,
               optimizer='Ftrl',
               config=None,
               loss_reduction=losses.Reduction.SUM):
    """Initializes a BaselineClassifier instance.

    Args:
      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.
        It must be greater than 1. Note: 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 will be multiplied by the loss of the example.
      label_vocabulary: Optional list of strings with size `[n_classes]`
        defining the label vocabulary. Only supported for `n_classes` > 2.
      optimizer: String, `tf.Optimizer` object, or callable that creates the
        optimizer to use for training. If not specified, will use
        `FtrlOptimizer` with a default learning rate of 0.3.
      config: `RunConfig` object to configure the runtime settings.
      loss_reduction: One of `tf.losses.Reduction` except `NONE`. Describes how
        to reduce training loss over batch. Defaults to `SUM`.
    Returns:
      A `BaselineClassifier` estimator.

    Raises:
      ValueError: If `n_classes` < 2.
    """
    if n_classes == 2:
      head = head_lib._binary_logistic_head_with_sigmoid_cross_entropy_loss(  # pylint: disable=protected-access
          weight_column=weight_column,
          label_vocabulary=label_vocabulary,
          loss_reduction=loss_reduction)
    else:
      head = head_lib._multi_class_head_with_softmax_cross_entropy_loss(  # pylint: disable=protected-access
          n_classes, weight_column=weight_column,
          label_vocabulary=label_vocabulary,
          loss_reduction=loss_reduction)
    def _model_fn(features, labels, mode, config):
      return _baseline_model_fn(
          features=features,
          labels=labels,
          mode=mode,
          head=head,
          optimizer=optimizer,
          weight_column=weight_column,
          config=config)
    super(BaselineClassifier, self).__init__(
        model_fn=_model_fn,
        model_dir=model_dir,
        config=config)

  def testWeightedCategoricalColumn(self):
    head_fn = head_lib._binary_logistic_head_with_sigmoid_cross_entropy_loss(
        loss_reduction=losses.Reduction.SUM_OVER_NONZERO_WEIGHTS)

    learner_config = learner_pb2.LearnerConfig()
    learner_config.num_classes = 2
    learner_config.constraints.max_tree_depth = 1
    model_dir = tempfile.mkdtemp()
    config = run_config.RunConfig()

    feature_columns = [
        core_feature_column.weighted_categorical_column(
            categorical_column=core_feature_column.
            categorical_column_with_vocabulary_list(
                key="word", vocabulary_list=["the", "cat", "dog"]),
            weight_feature_key="weight")
    ]

    labels = np.array([[1], [1], [0], [0.]], dtype=np.float32)

    def _make_input_fn():

      def _input_fn():
        features_dict = {}
        # Sparse tensor representing
        # example 0: "cat","the"
        # examaple 1: "dog"
        # example 2: -
        # example 3: "the"
        # Weights for the words are 5 - cat, 6- dog and 1 -the.
        features_dict["word"] = sparse_tensor.SparseTensor(
            indices=[[0, 0], [0, 1], [1, 0], [3, 0]],
            values=constant_op.constant(
                ["the", "cat", "dog", "the"], dtype=dtypes.string),
            dense_shape=[4, 3])
        features_dict["weight"] = sparse_tensor.SparseTensor(
            indices=[[0, 0], [0, 1], [1, 0], [3, 0]],
            values=[1., 5., 6., 1.],
            dense_shape=[4, 3])
        return features_dict, labels

      return _input_fn

    est = estimator.CoreGradientBoostedDecisionTreeEstimator(
        head=head_fn,
        learner_config=learner_config,
        num_trees=1,
        examples_per_layer=3,
        model_dir=model_dir,
        config=config,
        feature_columns=feature_columns)

    input_fn = _make_input_fn()
    est.train(input_fn=input_fn, steps=100)
    est.evaluate(input_fn=input_fn, steps=1)
    est.predict(input_fn=input_fn)

def binary_classification_head(
    weight_column=None, thresholds=None, label_vocabulary=None,
    loss_reduction=losses.Reduction.SUM, name=None):
  """Creates a `_Head` for single label binary classification.

  This head uses `sigmoid_cross_entropy_with_logits` loss.

  The head expects `logits` with shape `[D0, D1, ... DN, 1]`.
  In many applications, the shape is `[batch_size, 1]`.

  `labels` must be a dense `Tensor` with shape matching `logits`, namely
  `[D0, D1, ... DN, 1]`. If `label_vocabulary` given, `labels` must be a string
  `Tensor` with values from the vocabulary. If `label_vocabulary` is not given,
  `labels` must be float `Tensor` with values in the interval `[0, 1]`.

  If `weight_column` is specified, weights must be of shape
  `[D0, D1, ... DN]`, or `[D0, D1, ... DN, 1]`.

  The loss is the weighted sum over the input dimensions. Namely, if the input
  labels have shape `[batch_size, 1]`, the loss is the weighted sum over
  `batch_size`.

  Args:
    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.
    thresholds: Iterable of floats in the range `(0, 1)`. For binary
      classification metrics such as precision and recall, an eval metric is
      generated for each threshold value. This threshold is applied to the
      logistic values to determine the binary classification (i.e., above the
      threshold is `true`, below is `false`.
    label_vocabulary: A list or tuple of strings representing possible label
      values. If it is not given, labels must be float with values within
      [0, 1]. If given, labels must be string type and have any value in
      `label_vocabulary`. Note that errors will be raised if `label_vocabulary`
      is not provided but labels are strings.
    loss_reduction: One of `tf.losses.Reduction` except `NONE`. Describes how to
      reduce training loss over batch. Defaults to `SUM`.
    name: name of the head. If provided, summary and metrics keys will be
      suffixed by `"/" + name`. Also used as `name_scope` when creating ops.

  Returns:
    An instance of `_Head` for binary classification.

  Raises:
    ValueError: If `thresholds` contains a value outside of `(0, 1)`.
    ValueError: If `loss_reduction` is invalid.
  """
  return head_lib._binary_logistic_head_with_sigmoid_cross_entropy_loss(  # pylint:disable=protected-access
      weight_column=weight_column,
      thresholds=thresholds,
      label_vocabulary=label_vocabulary,
      loss_reduction=loss_reduction,
      name=name)

def _create_classification_head(n_classes,
                                weight_column=None,
                                label_vocabulary=None):
  """Creates a classification head. Refer to canned.head for details on args."""
  # TODO(nponomareva): Support multi-class cases.
  if n_classes == 2:
    # pylint: disable=protected-access
    return head_lib._binary_logistic_head_with_sigmoid_cross_entropy_loss(
        weight_column=weight_column,
        label_vocabulary=label_vocabulary,
        loss_reduction=losses.Reduction.SUM_OVER_BATCH_SIZE)
    # pylint: enable=protected-access
  else:
    raise ValueError('For now only binary classification is supported.'
                     'n_classes given as {}'.format(n_classes))

  def testTrainEvaluateWithDnnForInputAndTreeForPredict(self):
    head_fn = head_lib._binary_logistic_head_with_sigmoid_cross_entropy_loss(
        loss_reduction=losses.Reduction.SUM_OVER_NONZERO_WEIGHTS)

    learner_config = learner_pb2.LearnerConfig()
    learner_config.num_classes = 2
    learner_config.constraints.max_tree_depth = 3
    model_dir = tempfile.mkdtemp()
    config = run_config.RunConfig()

    est = estimator.CoreDNNBoostedTreeCombinedEstimator(
        head=head_fn,
        dnn_hidden_units=[1],
        dnn_feature_columns=[core_feature_column.numeric_column("x")],
        tree_learner_config=learner_config,
        num_trees=1,
        tree_examples_per_layer=3,
        model_dir=model_dir,
        config=config,
        dnn_steps_to_train=10,
        dnn_input_layer_to_tree=True,
        predict_with_tree_only=True,
        dnn_to_tree_distillation_param=(0.5, None),
        tree_feature_columns=[])

    # Train for a few steps.
    est.train(input_fn=_train_input_fn, steps=1000)
    res = est.evaluate(input_fn=_eval_input_fn, steps=1)
    self.assertLess(0.5, res["auc"])
    est.predict(input_fn=_eval_input_fn)
    serving_input_fn = (
        export.build_parsing_serving_input_receiver_fn(
            feature_spec={"x": parsing_ops.FixedLenFeature(
                [1], dtype=dtypes.float32)}))
    base_exporter = exporter.FinalExporter(
        name="Servo",
        serving_input_receiver_fn=serving_input_fn,
        assets_extra=None)
    export_path = os.path.join(model_dir, "export")
    base_exporter.export(
        est,
        export_path=export_path,
        checkpoint_path=None,
        eval_result={},
        is_the_final_export=True)

  def testTrainEvaluateInferDoesNotThrowError(self):
    head_fn = head_lib._binary_logistic_head_with_sigmoid_cross_entropy_loss(
        loss_reduction=losses.Reduction.SUM_OVER_NONZERO_WEIGHTS)

    learner_config = learner_pb2.LearnerConfig()
    learner_config.num_classes = 2
    learner_config.constraints.max_tree_depth = 1
    model_dir = tempfile.mkdtemp()
    config = run_config.RunConfig()

    est = estimator.CoreGradientBoostedDecisionTreeEstimator(
        head=head_fn,
        learner_config=learner_config,
        num_trees=1,
        examples_per_layer=3,
        model_dir=model_dir,
        config=config,
        feature_columns=[core_feature_column.numeric_column("x")])

    # Train for a few steps.
    est.train(input_fn=_train_input_fn, steps=1000)
    est.evaluate(input_fn=_eval_input_fn, steps=1)
    est.predict(input_fn=_eval_input_fn)

def binary_classification_head(
    weight_column=None, thresholds=None, label_vocabulary=None, name=None):
  """Creates a `_Head` for single label binary classification.

  This head uses `sigmoid_cross_entropy_with_logits` loss.

  This head expects to be fed float labels of shape `(batch_size, 1)`.

  Args:
    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.
    thresholds: Iterable of floats in the range `(0, 1)`. For binary
      classification metrics such as precision and recall, an eval metric is
      generated for each threshold value. This threshold is applied to the
      logistic values to determine the binary classification (i.e., above the
      threshold is `true`, below is `false`.
    label_vocabulary: A list of strings represents possible label values. If it
      is not given, that means labels are already encoded within [0, 1]. If
      given, labels must be string type and have any value in
      `label_vocabulary`. Also there will be errors if vocabulary is not
      provided and labels are string.
    name: name of the head. If provided, summary and metrics keys will be
      suffixed by `"/" + name`.

  Returns:
    An instance of `_Head` for binary classification.

  Raises:
    ValueError: if `thresholds` contains a value outside of `(0, 1)`.
  """
  return head_lib._binary_logistic_head_with_sigmoid_cross_entropy_loss(  # pylint:disable=protected-access
      weight_column=weight_column,
      thresholds=thresholds,
      label_vocabulary=label_vocabulary,
      name=name)

  def testFitAndEvaluateDontThrowExceptionWithCoreForEstimator(self):
    learner_config = learner_pb2.LearnerConfig()
    learner_config.num_classes = 2
    learner_config.constraints.max_tree_depth = 1
    model_dir = tempfile.mkdtemp()
    config = run_config.RunConfig()

    # Use core head
    head_fn = head_lib._binary_logistic_head_with_sigmoid_cross_entropy_loss(
        loss_reduction=losses.Reduction.SUM_OVER_BATCH_SIZE)

    model = estimator.GradientBoostedDecisionTreeEstimator(
        head=head_fn,
        learner_config=learner_config,
        num_trees=1,
        examples_per_layer=3,
        model_dir=model_dir,
        config=config,
        feature_columns=[core_feature_column.numeric_column("x")],
        use_core_libs=True)

    model.fit(input_fn=_train_input_fn, steps=15)
    model.evaluate(input_fn=_eval_input_fn, steps=1)
    model.export(self._export_dir_base)

  def __init__(self,
               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,
               sparse_combiner='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. Can also
        be a string (one of 'Adagrad', 'Adam', 'Ftrl', 'RMSProp', 'SGD'), or
        callable. 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`.
      sparse_combiner: A string specifying how to reduce if a categorical column
        is multivalent.  One of "mean", "sqrtn", and "sum" -- these are
        effectively different ways to do example-level normalization, which can
        be useful for bag-of-words features. for more details, see
        `tf.feature_column.linear_model`.

    Returns:
      A `LinearClassifier` estimator.

    Raises:
      ValueError: if n_classes < 2.
    """
    if n_classes == 2:
      head = head_lib._binary_logistic_head_with_sigmoid_cross_entropy_loss(  # pylint: disable=protected-access
          weight_column=weight_column,
          label_vocabulary=label_vocabulary,
          loss_reduction=loss_reduction)
    else:
      head = head_lib._multi_class_head_with_softmax_cross_entropy_loss(  # pylint: disable=protected-access
          n_classes, weight_column=weight_column,
          label_vocabulary=label_vocabulary,
          loss_reduction=loss_reduction)

    def _model_fn(features, labels, mode, config):
      """Call the defined shared _linear_model_fn."""
      return _linear_model_fn(
          features=features,
          labels=labels,
          mode=mode,
          head=head,
          feature_columns=tuple(feature_columns or []),
          optimizer=optimizer,
          partitioner=partitioner,
          config=config,
          sparse_combiner=sparse_combiner)

    super(LinearClassifier, self).__init__(
        model_fn=_model_fn,
        model_dir=model_dir,
        config=config,
        warm_start_from=warm_start_from)

def binary_classification_head(
    weight_column=None,
    thresholds=None,
    label_vocabulary=None,
    loss_reduction=losses.Reduction.SUM_OVER_BATCH_SIZE,
    loss_fn=None,
    name=None):
  """Creates a `_Head` for single label binary classification.

  This head uses `sigmoid_cross_entropy_with_logits` loss.

  The head expects `logits` with shape `[D0, D1, ... DN, 1]`.
  In many applications, the shape is `[batch_size, 1]`.

  `labels` must be a dense `Tensor` with shape matching `logits`, namely
  `[D0, D1, ... DN, 1]`. If `label_vocabulary` given, `labels` must be a string
  `Tensor` with values from the vocabulary. If `label_vocabulary` is not given,
  `labels` must be float `Tensor` with values in the interval `[0, 1]`.

  If `weight_column` is specified, weights must be of shape
  `[D0, D1, ... DN]`, or `[D0, D1, ... DN, 1]`.

  The loss is the weighted sum over the input dimensions. Namely, if the input
  labels have shape `[batch_size, 1]`, the loss is the weighted sum over
  `batch_size`.

  Also supports custom `loss_fn`. `loss_fn` takes `(labels, logits)` or
  `(labels, logits, features)` as arguments and returns unreduced loss with
  shape `[D0, D1, ... DN, 1]`. `loss_fn` must support float `labels` with
  shape `[D0, D1, ... DN, 1]`. Namely, the head applies `label_vocabulary` to
  the input labels before passing them to `loss_fn`.

  The head can be used with a canned estimator. Example:

  ```python
  my_head = tf.contrib.estimator.binary_classification_head()
  my_estimator = tf.contrib.estimator.DNNEstimator(
      head=my_head,
      hidden_units=...,
      feature_columns=...)
  ```

  It can also be used with a custom `model_fn`. Example:

  ```python
  def _my_model_fn(features, labels, mode):
    my_head = tf.contrib.estimator.binary_classification_head()
    logits = tf.keras.Model(...)(features)

    return my_head.create_estimator_spec(
        features=features,
        mode=mode,
        labels=labels,
        optimizer=tf.AdagradOptimizer(learning_rate=0.1),
        logits=logits)

  my_estimator = tf.estimator.Estimator(model_fn=_my_model_fn)
  ```

  Args:
    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.
    thresholds: Iterable of floats in the range `(0, 1)`. For binary
      classification metrics such as precision and recall, an eval metric is
      generated for each threshold value. This threshold is applied to the
      logistic values to determine the binary classification (i.e., above the
      threshold is `true`, below is `false`.
    label_vocabulary: A list or tuple of strings representing possible label
      values. If it is not given, labels must be float with values within
      [0, 1]. If given, labels must be string type and have any value in
      `label_vocabulary`. Note that errors will be raised if `label_vocabulary`
      is not provided but labels are strings.
    loss_reduction: One of `tf.losses.Reduction` except `NONE`. Describes how to
      reduce training loss over batch. Defaults to `SUM_OVER_BATCH_SIZE`, namely
      weighted sum of losses divided by batch size. See `tf.losses.Reduction`.
    loss_fn: Optional loss function.
    name: name of the head. If provided, summary and metrics keys will be
      suffixed by `"/" + name`. Also used as `name_scope` when creating ops.

  Returns:
    An instance of `_Head` for binary classification.

  Raises:
    ValueError: If `thresholds` contains a value outside of `(0, 1)`.
    ValueError: If `loss_reduction` is invalid.
  """
  return head_lib._binary_logistic_head_with_sigmoid_cross_entropy_loss(  # pylint:disable=protected-access
      weight_column=weight_column,
      thresholds=thresholds,
      label_vocabulary=label_vocabulary,
      loss_reduction=loss_reduction,
      loss_fn=loss_fn,
      name=name)

  def __init__(self,
               model_dir=None,
               linear_feature_columns=None,
               linear_optimizer='Ftrl',
               dnn_feature_columns=None,
               dnn_optimizer='Adagrad',
               dnn_hidden_units=None,
               dnn_activation_fn=nn.relu,
               dnn_dropout=None,
               n_classes=2,
               weight_column=None,
               label_vocabulary=None,
               input_layer_partitioner=None,
               config=None,
               warm_start_from=None,
               loss_reduction=losses.Reduction.SUM):
    """Initializes a DNNLinearCombinedClassifier instance.

    Args:
      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.
      linear_feature_columns: An iterable containing all the feature columns
        used by linear part of the model. All items in the set must be
        instances of classes derived from `FeatureColumn`.
      linear_optimizer: An instance of `tf.Optimizer` used to apply gradients to
        the linear part of the model. Defaults to FTRL optimizer.
      dnn_feature_columns: An iterable containing all the feature columns used
        by deep part of the model. All items in the set must be instances of
        classes derived from `FeatureColumn`.
      dnn_optimizer: An instance of `tf.Optimizer` used to apply gradients to
        the deep part of the model. Defaults to Adagrad optimizer.
      dnn_hidden_units: List of hidden units per layer. All layers are fully
        connected.
      dnn_activation_fn: Activation function applied to each layer. If None,
        will use `tf.nn.relu`.
      dnn_dropout: When not None, the probability we will drop out
        a given coordinate.
      n_classes: Number of label classes. Defaults to 2, namely binary
        classification. Must be > 1.
      weight_column: A string or a `_NumericColumn` created by
        `tf.feature_column.numeric_column` defining feature column representing
        weights. It is used to down weight or boost examples during training. It
        will be multiplied by the loss of the example. If it is a string, it is
        used as a key to fetch weight tensor from the `features`. If it is a
        `_NumericColumn`, raw tensor is fetched by key `weight_column.key`,
        then weight_column.normalizer_fn is applied on it to get weight tensor.
      label_vocabulary: A list of strings represents possible label values. If
        given, labels must be string type and have any value in
        `label_vocabulary`. If it is not given, that means labels are
        already encoded as integer or float within [0, 1] for `n_classes=2` and
        encoded as integer values in {0, 1,..., n_classes-1} for `n_classes`>2 .
        Also there will be errors if vocabulary is not provided and labels are
        string.
      input_layer_partitioner: Partitioner for input layer. Defaults to
        `min_max_variable_partitioner` with `min_slice_size` 64 << 20.
      config: RunConfig object to configure the runtime settings.
      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 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`.

    Raises:
      ValueError: If both linear_feature_columns and dnn_features_columns are
        empty at the same time.
    """
    linear_feature_columns = linear_feature_columns or []
    dnn_feature_columns = dnn_feature_columns or []
    self._feature_columns = (
        list(linear_feature_columns) + list(dnn_feature_columns))
    if not self._feature_columns:
      raise ValueError('Either linear_feature_columns or dnn_feature_columns '
                       'must be defined.')
    if n_classes == 2:
      head = head_lib._binary_logistic_head_with_sigmoid_cross_entropy_loss(  # pylint: disable=protected-access
          weight_column=weight_column,
          label_vocabulary=label_vocabulary,
          loss_reduction=loss_reduction)
    else:
      head = head_lib._multi_class_head_with_softmax_cross_entropy_loss(  # pylint: disable=protected-access
          n_classes,
          weight_column=weight_column,
          label_vocabulary=label_vocabulary,
          loss_reduction=loss_reduction)

    def _model_fn(features, labels, mode, config):
      """Call the _dnn_linear_combined_model_fn."""
      return _dnn_linear_combined_model_fn(
          features=features,
          labels=labels,
          mode=mode,
          head=head,
          linear_feature_columns=linear_feature_columns,
          linear_optimizer=linear_optimizer,
          dnn_feature_columns=dnn_feature_columns,
          dnn_optimizer=dnn_optimizer,
          dnn_hidden_units=dnn_hidden_units,
#.........这里部分代码省略.........