Closest README

A C library for k-nearest neighbor search in N-dimensions with arbitrary metric functions.

Closest:

• is simple to use
• is flexible (custom distance functions)
• provides API interfaces for C, C++ and Python
• written in ISO C99
• has no external dependencies
• is small and fast
• is well documented

Closest is licensed under the GPL-3.0 (see the LICENSE file for details).

Code Example

Find the k = 10 nearest neighbors to a point x in an array data of 1000 points in d = 20 dimensions:

int d = 20;
int k = 10;
int n = 1000;

/*
   double *data[n*d] has been filled with 1000 points in d=20 dimensions, each
   of the 20 coordinates for a point followed by the next until all 1000
   are specified.

   x is the point where the nearest neighbors query is done
*/

/* initialize the search */
cell_t *cell = cell_init( d, n, data, -1 );

int i_cell[k];
int d_cell[k];
/* cell_knearest returns
     in i_cell, the index for the points in the `data` array of the k-nearest neighbors to x
     in d_cell, the distances for those same points to x */
cell_knearest( cell, 1, x, k, i_cell, d_cell );
cell_free(cell);

Compilation and installation

Closest uses cmake as build system. To build and install a dynamic version of closest in /usr/local:

Documentation

Documentation is available at http://trifling-matters.com/closest.html.

The documentation source is in the doc/ subdirectory. To generate the HTML documentation, invoke:

$ make html

Then, point your browser to doc/bld/index.html.