lwmpoint_median()

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

extern

Definition at line 231 of file lwgeom_median.c.

{
        /* m ordinate is considered weight, if defined */
        uint32_t npoints = 0; /* we need to count this ourselves so we can exclude empties and weightless points */
        uint32_t i;
        int input_empty = LW_TRUE;
        POINT3D median;
        POINT4D* points = lwmpoint_extract_points_4d(g, &npoints, &input_empty);
 
        /* input validation failed, error reported already */
        if (points == NULL) return NULL;
 
        if (npoints == 0)
        {
                lwfree(points);
                if (input_empty)
                {
                        return lwpoint_construct_empty(g->srid, 0, 0);
                }
                else
                {
                        lwerror("Median failed to find non-empty input points with positive weight.");
                        return NULL;
                }
        }
 
        median = init_guess(points, npoints);
 
        i = iterate_4d(&median, points, npoints, max_iter, tol);
 
        lwfree(points);
 
        if (fail_if_not_converged && i >= max_iter)
        {
                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);
        }
}

References init_guess(), iterate_4d(), LW_TRUE, lwerror(), lwfree(), lwgeom_has_z(), lwmpoint_extract_points_4d(), lwpoint_construct_empty(), lwpoint_make2d(), lwpoint_make3dz(), LWMPOINT::srid, POINT3D::x, POINT3D::y, and POINT3D::z.

Referenced by lwgeom_median().

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