lwmpoint_median()

LWPOINT* lwmpoint_median	(	const LWMPOINT *	g,
		double	tol,
		uint32_t	max_iter,
		char	fail_if_not_converged
	)

Definition at line 159 of file lwgeom_median.c.

References init_guess(), iterate_3d(), lwalloc(), lwerror(), lwfree(), lwgeom_has_z(), lwmpoint_extract_points_3d(), lwpoint_construct_empty(), lwpoint_make2d(), lwpoint_make3dz(), LWGEOM::srid, LWMPOINT::srid, POINT3D::x, POINT3D::y, and POINT3D::z.

Referenced by lwgeom_median().

{
        uint32_t npoints; /* we need to count this ourselves so we can exclude empties */
        uint32_t i;
        double delta = DBL_MAX;
        double* distances;
        POINT3D* points = lwmpoint_extract_points_3d(g, &npoints);
        POINT3D median;

        if (npoints == 0)
        {
                lwfree(points);
                return lwpoint_construct_empty(g->srid, 0, 0);
        }

        median = init_guess(points, npoints);

        distances = lwalloc(npoints * sizeof(double));

        for (i = 0; i < max_iter && delta > tol; i++)
        {
                delta = iterate_3d(&median, points, npoints, distances);
        }

        lwfree(points);
        lwfree(distances);

        if (fail_if_not_converged && delta > tol)
        {
                lwerror("Median failed to converge within %g after %d iterations.", tol, max_iter);
                return NULL;
        }

        if (lwgeom_has_z((LWGEOM*) g))
        {
                return lwpoint_make3dz(g->srid, median.x, median.y, median.z);
        }
        else
        {
                return lwpoint_make2d(g->srid, median.x, median.y);
        }
}

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