knnring.h

/*
 * knnring.h
 *
 *  Created on: Nov 21, 2019
 *      Author: Lambis
 */


#ifndef KNNRING_H_
#define KNNRING_H_

// Definition of the kNN result struct.
typedef struct knnresult{
	int *nidx;			//!< Indices (0-based) of nearest neighbors [m-by-k]
	double *ndist;		//!< Distance of nearest neighbors 			[m-by-k]
	int m;				//!< Number of query points 				[scalar]
	int k;				//!< Number of nearest neighbors 			[scalar]
} knnresult;

//! Compute k nearest neighbors of each point in X [n-by-d]
/*!
	\param X	Corpus data points			[n-by-d]
	\param Y	Query data points			[m-by-d]
	\param n	Number of corpus points		[scalar]
	\param m	Number of query points		[scalar]
	\param d	Number of dimensions		[scalar]
	\param k	Number of neighbors			[scalar]

	\return The kNN result
*/
knnresult kNN(double * X, double * Y, int n, int m, int d, int k);

//! Compute distributed all-kNN of points in X
/*!
    \param X    Data points                 [n-by-d]
    \param n    Number of data points       [scalar]
    \param d    Number of dimensions        [scalar]
    \param k    Number of neighbors         [scalar]

    \return The kNN result
*/
knnresult distrAllkNN(double * X, int n, int d, int k);

void swap(void* a, void* b, size_t s);
int partition(double *arr, int low, int high, int *idx);
void quickSort(double *arr, int low, int high, int *idx);

#endif /* KNNRING_H_ */