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Purpose: updated the core chapter
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@@ -14,24 +14,23 @@ kmeans
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:param samples: Floating-point matrix of input samples, one row per sample.
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:param clusterCount: The number of clusters to split the set by.
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:param clusterCount: Number of clusters to split the set by.
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:param labels: The input/output integer array that stores the cluster indices for every sample.
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:param labels: Input/output integer array that stores the cluster indices for every sample.
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:param termcrit: Specifies the maximum number of iterations and/or accuracy (distance the centers can move by between subsequent iterations)
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:param termcrit: Flag to specify the maximum number of iterations and/or accuracy (distance the centers can move by between subsequent iterations??).
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:param attempts: How many times the algorithm is executed using different initial labelings. The algorithm returns the labels that yield the best compactness (see the last function parameter)
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:param attempts: Flag to specify how many times the algorithm is executed using different initial labelings. The algorithm returns the labels that yield the best compactness (see the last function parameter).
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:param flags: It can take the following values:
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:param flags: Flag that can take the following values:
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* **KMEANS_RANDOM_CENTERS** Random initial centers are selected in each attempt
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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
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* **KMEANS_PP_CENTERS** Use ``kmeans++`` center initialization by Arthur and Vassilvitskii.
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* **KMEANS_USE_INITIAL_LABELS** During the first (and possibly the only) attempt, the
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function uses the user-supplied labels instaed of computing them from the initial centers. For the second and further attempts, the function will use the random or semi-random centers (use one of ``KMEANS_*_CENTERS`` flag to specify the exact method)
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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: The output matrix of the cluster centers, one row per each cluster center
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:param centers: Output matrix of the cluster centers, one row per each cluster center.
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The function ``kmeans`` implements a k-means algorithm that finds the
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centers of ``clusterCount`` clusters and groups the input samples
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@@ -46,10 +45,10 @@ The function returns the compactness measure, which is computed as
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\sum _i \| \texttt{samples} _i - \texttt{centers} _{ \texttt{labels} _i} \| ^2
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after every attempt; the best (minimum) value is chosen and the
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after every attempt. The best (minimum) value is chosen and the
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corresponding labels and the compactness value are returned by the function.
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Basically, the user can use only the core of the function, set the number of
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attempts to 1, initialize labels each time using some custom algorithm and pass them with
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Basically, you can use only the core of the function, set the number of
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attempts to 1, initialize labels each time using a custom algorithm, pass them with the
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( ``flags`` = ``KMEANS_USE_INITIAL_LABELS`` ) flag, and then choose the best (most-compact) clustering.
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.. index:: partition
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@@ -62,9 +61,11 @@ partition
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Splits an element set into equivalency classes.
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:param vec: The set of elements stored as a vector
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:param vec: Set of elements stored as a vector.
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:param labels: The output vector of labels; will contain as many elements as ``vec`` . Each label ``labels[i]`` is 0-based cluster index of ``vec[i]`` :param predicate: The equivalence predicate (i.e. pointer to a boolean function of two arguments or an instance of the class that has the method ``bool operator()(const _Tp& a, const _Tp& b)`` . The predicate returns true when the elements are certainly if the same class, and false if they may or may not be in the same class
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:param labels: Output vector of labels. It contains as many elements as ``vec`` . Each label ``labels[i]`` is a 0-based cluster index of ``vec[i]`` .
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:param predicate: Equivalence predicate (pointer to a boolean function of two arguments or an instance of the class that has the method ``bool operator()(const _Tp& a, const _Tp& b)`` ). The predicate returns ``true`` when the elements are certainly in the same class, and returns ``false`` if they may or may not be in the same class.
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The generic function ``partition`` implements an
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:math:`O(N^2)` algorithm for
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