code: # Copyright 2015 The TensorFlow Authors. All Rights Reserved.
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #     http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  # ==============================================================================
  """Wrapper for using the Scikit-Learn API with Keras models."""
  # pylint: disable=g-classes-have-attributes
  
  import copy
  import types
  
  import numpy as np
  
  from keras import losses
  from keras.models import Sequential
  from keras.utils.generic_utils import has_arg
  from keras.utils.np_utils import to_categorical
  from tensorflow.python.util.tf_export import keras_export
  
  
  class BaseWrapper(object):
    """Base class for the Keras scikit-learn wrapper.
  
    Warning: This class should not be used directly.
    Use descendant classes instead.
  
    Args:
        build_fn: callable function or class instance
        **sk_params: model parameters & fitting parameters
  
    The `build_fn` should construct, compile and return a Keras model, which
    will then be used to fit/predict. One of the following
    three values could be passed to `build_fn`:
    1. A function
    2. An instance of a class that implements the `__call__` method
    3. None. This means you implement a class that inherits from either
    `KerasClassifier` or `KerasRegressor`. The `__call__` method of the
    present class will then be treated as the default `build_fn`.
  
    `sk_params` takes both model parameters and fitting parameters. Legal model
    parameters are the arguments of `build_fn`. Note that like all other
    estimators in scikit-learn, `build_fn` should provide default values for
    its arguments, so that you could create the estimator without passing any
    values to `sk_params`.
  
    `sk_params` could also accept parameters for calling `fit`, `predict`,
    `predict_proba`, and `score` methods (e.g., `epochs`, `batch_size`).
    fitting (predicting) parameters are selected in the following order:
  
    1. Values passed to the dictionary arguments of
    `fit`, `predict`, `predict_proba`, and `score` methods
    2. Values passed to `sk_params`
    3. The default values of the `keras.models.Sequential`
    `fit`, `predict`, `predict_proba` and `score` methods
  
    When using scikit-learn's `grid_search` API, legal tunable parameters are
    those you could pass to `sk_params`, including fitting parameters.
    In other words, you could use `grid_search` to search for the best
    `batch_size` or `epochs` as well as the model parameters.
    """
  
    def __init__(self, build_fn=None, **sk_params):
      self.build_fn = build_fn
      self.sk_params = sk_params
      self.check_params(sk_params)
  
    def check_params(self, params):
      """Checks for user typos in `params`.
  
      Args:
          params: dictionary; the parameters to be checked
  
      Raises:
          ValueError: if any member of `params` is not a valid argument.
      """
      legal_params_fns = [
          Sequential.fit, Sequential.predict, Sequential.predict_classes,
          Sequential.evaluate
      ]
      if self.build_fn is None:
        legal_params_fns.append(self.__call__)
      elif (not isinstance(self.build_fn, types.FunctionType) and
            not isinstance(self.build_fn, types.MethodType)):
        legal_params_fns.append(self.build_fn.__call__)
      else:
        legal_params_fns.append(self.build_fn)
  
      for params_name in params:
        for fn in legal_params_fns:
          if has_arg(fn, params_name):
            break
        else:
          if params_name != 'nb_epoch':
            raise ValueError('{} is not a legal parameter'.format(params_name))
  
    def get_params(self, **params):  # pylint: disable=unused-argument
      """Gets parameters for this estimator.
  
      Args:
          **params: ignored (exists for API compatibility).
  
      Returns:
          Dictionary of parameter names mapped to their values.
      """
      res = self.sk_params.copy()
      res.update({'build_fn': self.build_fn})
      return res
  
    def set_params(self, **params):
      """Sets the parameters of this estimator.
  
      Args:
          **params: Dictionary of parameter names mapped to their values.
  
      Returns:
          self
      """
      self.check_params(params)
      self.sk_params.update(params)
      return self
  
    def fit(self, x, y, **kwargs):
      """Constructs a new model with `build_fn` & fit the model to `(x, y)`.
  
      Args:
          x : array-like, shape `(n_samples, n_features)`
              Training samples where `n_samples` is the number of samples
              and `n_features` is the number of features.
          y : array-like, shape `(n_samples,)` or `(n_samples, n_outputs)`
              True labels for `x`.
          **kwargs: dictionary arguments
              Legal arguments are the arguments of `Sequential.fit`
  
      Returns:
          history : object
              details about the training history at each epoch.
      """
      if self.build_fn is None:
        self.model = self.__call__(**self.filter_sk_params(self.__call__))
      elif (not isinstance(self.build_fn, types.FunctionType) and
            not isinstance(self.build_fn, types.MethodType)):
        self.model = self.build_fn(
            **self.filter_sk_params(self.build_fn.__call__))
      else:
        self.model = self.build_fn(**self.filter_sk_params(self.build_fn))
  
      if (losses.is_categorical_crossentropy(self.model.loss) and
          len(y.shape) != 2):
        y = to_categorical(y)
  
      fit_args = copy.deepcopy(self.filter_sk_params(Sequential.fit))
      fit_args.update(kwargs)
  
      history = self.model.fit(x, y, **fit_args)
  
      return history
  
    def filter_sk_params(self, fn, override=None):
      """Filters `sk_params` and returns those in `fn`'s arguments.
  
      Args:
          fn : arbitrary function
          override: dictionary, values to override `sk_params`
  
      Returns:
          res : dictionary containing variables
              in both `sk_params` and `fn`'s arguments.
      """
      override = override or {}
      res = {}
      for name, value in self.sk_params.items():
        if has_arg(fn, name):
          res.update({name: value})
      res.update(override)
      return res
  
  
  @keras_export('keras.wrappers.scikit_learn.KerasClassifier')
  class KerasClassifier(BaseWrapper):
    """Implementation of the scikit-learn classifier API for Keras.
    """
  
    def fit(self, x, y, **kwargs):
      """Constructs a new model with `build_fn` & fit the model to `(x, y)`.
  
      Args:
          x : array-like, shape `(n_samples, n_features)`
              Training samples where `n_samples` is the number of samples
              and `n_features` is the number of features.
          y : array-like, shape `(n_samples,)` or `(n_samples, n_outputs)`
              True labels for `x`.
          **kwargs: dictionary arguments
              Legal arguments are the arguments of `Sequential.fit`
  
      Returns:
          history : object
              details about the training history at each epoch.
  
      Raises:
          ValueError: In case of invalid shape for `y` argument.
      """
      y = np.array(y)
      if len(y.shape) == 2 and y.shape[1] > 1:
        self.classes_ = np.arange(y.shape[1])
      elif (len(y.shape) == 2 and y.shape[1] == 1) or len(y.shape) == 1:
        self.classes_ = np.unique(y)
        y = np.searchsorted(self.classes_, y)
      else:
        raise ValueError('Invalid shape for y: ' + str(y.shape))
      self.n_classes_ = len(self.classes_)
      return super(KerasClassifier, self).fit(x, y, **kwargs)
  
    def predict(self, x, **kwargs):
      """Returns the class predictions for the given test data.
  
      Args:
          x: array-like, shape `(n_samples, n_features)`
              Test samples where `n_samples` is the number of samples
              and `n_features` is the number of features.
          **kwargs: dictionary arguments
              Legal arguments are the arguments
              of `Sequential.predict_classes`.
  
      Returns:
          preds: array-like, shape `(n_samples,)`
              Class predictions.
      """
      kwargs = self.filter_sk_params(Sequential.predict_classes, kwargs)
      classes = self.model.predict_classes(x, **kwargs)
      return self.classes_[classes]
  
    def predict_proba(self, x, **kwargs):
      """Returns class probability estimates for the given test data.
  
      Args:
          x: array-like, shape `(n_samples, n_features)`
              Test samples where `n_samples` is the number of samples
              and `n_features` is the number of features.
          **kwargs: dictionary arguments
              Legal arguments are the arguments
              of `Sequential.predict_classes`.
  
      Returns:
          proba: array-like, shape `(n_samples, n_outputs)`
              Class probability estimates.
              In the case of binary classification,
              to match the scikit-learn API,
              will return an array of shape `(n_samples, 2)`
              (instead of `(n_sample, 1)` as in Keras).
      """
      kwargs = self.filter_sk_params(Sequential.predict_proba, kwargs)
      probs = self.model.predict(x, **kwargs)
  
      # check if binary classification
      if probs.shape[1] == 1:
        # first column is probability of class 0 and second is of class 1
        probs = np.hstack([1 - probs, probs])
      return probs
  
    def score(self, x, y, **kwargs):
      """Returns the mean accuracy on the given test data and labels.
  
      Args:
          x: array-like, shape `(n_samples, n_features)`
              Test samples where `n_samples` is the number of samples
              and `n_features` is the number of features.
          y: array-like, shape `(n_samples,)` or `(n_samples, n_outputs)`
              True labels for `x`.
          **kwargs: dictionary arguments
              Legal arguments are the arguments of `Sequential.evaluate`.
  
      Returns:
          score: float
              Mean accuracy of predictions on `x` wrt. `y`.
  
      Raises:
          ValueError: If the underlying model isn't configured to
              compute accuracy. You should pass `metrics=["accuracy"]` to
              the `.compile()` method of the model.
      """
      y = np.searchsorted(self.classes_, y)
      kwargs = self.filter_sk_params(Sequential.evaluate, kwargs)
  
      loss_name = self.model.loss
      if hasattr(loss_name, '__name__'):
        loss_name = loss_name.__name__
      if loss_name == 'categorical_crossentropy' and len(y.shape) != 2:
        y = to_categorical(y)
  
      outputs = self.model.evaluate(x, y, **kwargs)
      if not isinstance(outputs, list):
        outputs = [outputs]
      for name, output in zip(self.model.metrics_names, outputs):
        if name in ['accuracy', 'acc']:
          return output
      raise ValueError('The model is not configured to compute accuracy. '
                       'You should pass `metrics=["accuracy"]` to '
                       'the `model.compile()` method.')
  
  
  @keras_export('keras.wrappers.scikit_learn.KerasRegressor')
  class KerasRegressor(BaseWrapper):
    """Implementation of the scikit-learn regressor API for Keras.
    """
  
    def predict(self, x, **kwargs):
      """Returns predictions for the given test data.
  
      Args:
          x: array-like, shape `(n_samples, n_features)`
              Test samples where `n_samples` is the number of samples
              and `n_features` is the number of features.
          **kwargs: dictionary arguments
              Legal arguments are the arguments of `Sequential.predict`.
  
      Returns:
          preds: array-like, shape `(n_samples,)`
              Predictions.
      """
      kwargs = self.filter_sk_params(Sequential.predict, kwargs)
      return np.squeeze(self.model.predict(x, **kwargs))
  
    def score(self, x, y, **kwargs):
      """Returns the mean loss on the given test data and labels.
  
      Args:
          x: array-like, shape `(n_samples, n_features)`
              Test samples where `n_samples` is the number of samples
              and `n_features` is the number of features.
          y: array-like, shape `(n_samples,)`
              True labels for `x`.
          **kwargs: dictionary arguments
              Legal arguments are the arguments of `Sequential.evaluate`.
  
      Returns:
          score: float
              Mean accuracy of predictions on `x` wrt. `y`.
      """
      kwargs = self.filter_sk_params(Sequential.evaluate, kwargs)
      loss = self.model.evaluate(x, y, **kwargs)
      if isinstance(loss, list):
        return -loss[0]
      return -loss
  
apis: numpy.searchsorted numpy.arange numpy.hstack tensorflow.python.util.tf_export.keras_export numpy.array numpy.unique