.. ******************************************************************************
.. * Copyright 2020 Intel Corporation
.. *
.. * 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
.. *
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.. * 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.
.. *******************************************************************************/

.. highlight:: cpp
.. default-domain:: cpp

.. _api_kmeans:

=======
K-Means
=======

.. include:: ../../../includes/clustering/kmeans-introduction.rst

------------------------
Mathematical formulation
------------------------

Refer to :ref:`Developer Guide: K-Means <alg_kmeans>`.

---------------------
Programming Interface
---------------------

All types and functions in this section are declared in the
``oneapi::dal::kmeans`` namespace and be available via inclusion of the
``oneapi/dal/algo/kmeans.hpp`` header file.

Descriptor
----------
.. onedal_class:: oneapi::dal::kmeans::descriptor

Method tags
~~~~~~~~~~~
.. onedal_tags_namespace:: oneapi::dal::kmeans::method

Task tags
~~~~~~~~~
.. onedal_tags_namespace:: oneapi::dal::kmeans::task

Model
-----
.. onedal_class:: oneapi::dal::kmeans::model


.. _kmeans_t_api:

Training :cpp:expr:`train(...)`
--------------------------------

.. _kmeans_t_api_input:

Input
~~~~~
.. onedal_class:: oneapi::dal::kmeans::train_input

.. _kmeans_t_api_result:

Result
~~~~~~
.. onedal_class:: oneapi::dal::kmeans::train_result

Operation
~~~~~~~~~

.. function:: template <typename Descriptor> \
              kmeans::train_result train(const Descriptor& desc, \
                                         const kmeans::train_input& input)

   :param desc: K-Means algorithm descriptor :expr:`kmeans::descriptor`
   :param input: Input data for the training operation

   Preconditions
      | :expr:`input.data.has_data == true`
      | :expr:`input.initial_centroids.row_count == desc.cluster_count`
      | :expr:`input.initial_centroids.column_count == input.data.column_count`
   Postconditions
      | :expr:`result.labels.row_count == input.data.row_count`
      | :expr:`result.labels.column_count == 1`
      | :expr:`result.labels[i] >= 0`
      | :expr:`result.labels[i] < desc.cluster_count`
      | :expr:`result.iteration_count <= desc.max_iteration_count`
      | :expr:`result.model.centroids.row_count == desc.cluster_count`
      | :expr:`result.model.centroids.column_count == input.data.column_count`

.. _kmeans_i_api:

Inference :cpp:expr:`infer(...)`
---------------------------------

.. _kmeans_i_api_input:

Input
~~~~~
.. onedal_class:: oneapi::dal::kmeans::infer_input

.. _kmeans_i_api_result:

Result
~~~~~~
.. onedal_class:: oneapi::dal::kmeans::infer_result

Operation
~~~~~~~~~

.. function:: template <typename Descriptor> \
              kmeans::infer_result infer(const Descriptor& desc, \
                                         const kmeans::infer_input& input)

   :param desc: K-Means algorithm descriptor :expr:`kmeans::descriptor`
   :param input: Input data for the inference operation

   Preconditions
      | :expr:`input.data.has_data == true`
      | :expr:`input.model.centroids.has_data == true`
      | :expr:`input.model.centroids.row_count == desc.cluster_count`
      | :expr:`input.model.centroids.column_count == input.data.column_count`
   Postconditions
      | :expr:`result.labels.row_count == input.data.row_count`
      | :expr:`result.labels.column_count == 1`
      | :expr:`result.labels[i] >= 0`
      | :expr:`result.labels[i] < desc.cluster_count`


-------------
Usage Example
-------------

.. include:: ../../../includes/clustering/kmeans-usage-examples.rst

--------
Examples
--------

.. include:: ../../../includes/clustering/kmeans-examples.rst