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Open Source Computer Vision Library
https://opencv.org/
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88 lines
4.3 KiB
88 lines
4.3 KiB
ml.Machine Learning |
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============================= |
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.. highlight:: cpp |
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ocl::KNearestNeighbour |
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.. ocv:class:: ocl::KNearestNeighbour |
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The class implements K-Nearest Neighbors model as described in the beginning of this section. |
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ocl::KNearestNeighbour |
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Computes the weighted sum of two arrays. :: |
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class CV_EXPORTS KNearestNeighbour: public CvKNearest |
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{ |
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public: |
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KNearestNeighbour(); |
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~KNearestNeighbour(); |
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bool train(const Mat& trainData, Mat& labels, Mat& sampleIdx = Mat().setTo(Scalar::all(0)), |
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bool isRegression = false, int max_k = 32, bool updateBase = false); |
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void clear(); |
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void find_nearest(const oclMat& samples, int k, oclMat& lables); |
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private: |
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/* hidden */ |
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}; |
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ocl::KNearestNeighbour::train |
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--------------------------------- |
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Trains the model. |
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.. ocv:function:: bool ocl::KNearestNeighbour::train(const Mat& trainData, Mat& labels, Mat& sampleIdx = Mat().setTo(Scalar::all(0)), bool isRegression = false, int max_k = 32, bool updateBase = false) |
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:param isRegression: Type of the problem: ``true`` for regression and ``false`` for classification. |
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:param maxK: Number of maximum neighbors that may be passed to the method :ocv:func:`CvKNearest::find_nearest`. |
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:param updateBase: Specifies whether the model is trained from scratch (``update_base=false``), or it is updated using the new training data (``update_base=true``). In the latter case, the parameter ``maxK`` must not be larger than the original value. |
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The method trains the K-Nearest model. It follows the conventions of the generic :ocv:func:`CvStatModel::train` approach with the following limitations: |
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* Only ``CV_ROW_SAMPLE`` data layout is supported. |
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* Input variables are all ordered. |
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* Output variables can be either categorical ( ``is_regression=false`` ) or ordered ( ``is_regression=true`` ). |
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* Variable subsets (``var_idx``) and missing measurements are not supported. |
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ocl::KNearestNeighbour::find_nearest |
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Finds the neighbors and predicts responses for input vectors. |
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.. ocv:function:: void ocl::KNearestNeighbour::find_nearest(const oclMat& samples, int k, oclMat& lables ) |
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:param samples: Input samples stored by rows. It is a single-precision floating-point matrix of :math:`number\_of\_samples \times number\_of\_features` size. |
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:param k: Number of used nearest neighbors. It must satisfy constraint: :math:`k \le` :ocv:func:`CvKNearest::get_max_k`. |
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:param labels: Vector with results of prediction (regression or classification) for each input sample. It is a single-precision floating-point vector with ``number_of_samples`` elements. |
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ocl::kmeans |
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--------------- |
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Finds centers of clusters and groups input samples around the clusters. |
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.. ocv:function:: double ocl::kmeans(const oclMat &src, int K, oclMat &bestLabels, TermCriteria criteria, int attemps, int flags, oclMat ¢ers) |
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:param src: Floating-point matrix of input samples, one row per sample. |
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:param K: Number of clusters to split the set by. |
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:param bestLabels: Input/output integer array that stores the cluster indices for every sample. |
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:param criteria: The algorithm termination criteria, that is, the maximum number of iterations and/or the desired accuracy. The accuracy is specified as ``criteria.epsilon``. As soon as each of the cluster centers moves by less than ``criteria.epsilon`` on some iteration, the algorithm stops. |
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:param attempts: Flag to specify the number of times the algorithm is executed using different initial labellings. The algorithm returns the labels that yield the best compactness (see the last function parameter). |
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:param flags: Flag that can take the following values: |
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* **KMEANS_RANDOM_CENTERS** Select random initial centers in each attempt. |
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* **KMEANS_PP_CENTERS** Use ``kmeans++`` center initialization by Arthur and Vassilvitskii [Arthur2007]. |
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* **KMEANS_USE_INITIAL_LABELS** During the first (and possibly the only) attempt, use the user-supplied labels instead of computing them from the initial centers. For the second and further attempts, use the random or semi-random centers. Use one of ``KMEANS_*_CENTERS`` flag to specify the exact method. |
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:param centers: Output matrix of the cluster centers, one row per each cluster center. |