improve_structure()

static uint32_t improve_structure ( POINT4D *  objs, uint32_t *  clusters, uint32_t  n, POINT4D *  centers, double *  radii, uint32_t  k, double  max_radius  )

static

Definition at line 42 of file lwkmeans.c.

{
        /* Input check: radius limit should be measurable */
        if (max_radius <= 0)
                return k;
 
        double max_radius_sq = max_radius * max_radius;
 
        /* Do we have the big clusters to split at all? */
        uint32_t first_cluster_to_split = 0;
        for (; first_cluster_to_split < k; first_cluster_to_split++)
                if (radii[first_cluster_to_split] > max_radius_sq)
                        break;
        if (first_cluster_to_split == k)
                return k;
 
        POINT4D *temp_objs = lwalloc(sizeof(POINT4D) * n);
        uint32_t *temp_clusters = lwalloc(sizeof(uint32_t) * n);
        double *temp_radii = lwalloc(sizeof(double) * n);
        POINT4D *temp_centers = lwalloc(sizeof(POINT4D) * n);
 
        uint32_t new_k = k;
 
        for (uint32_t cluster = first_cluster_to_split; cluster < k; cluster++)
        {
                if (radii[cluster] <= max_radius_sq)
                        continue;
 
                /* copy cluster alone */
                uint32_t cluster_size = 0;
                for (uint32_t i = 0; i < n; i++)
                        if (clusters[i] == cluster)
                                temp_objs[cluster_size++] = objs[i];
                if (cluster_size <= 1)
                        continue;
 
                /* run 2-means on the cluster */
                kmeans(temp_objs, temp_clusters, cluster_size, temp_centers, temp_radii, 2, 0);
 
                /* replace cluster with split */
                uint32_t d = 0;
                for (uint32_t i = 0; i < n; i++)
                        if (clusters[i] == cluster)
                                if (temp_clusters[d++])
                                        clusters[i] = new_k;
 
                centers[cluster] = temp_centers[0];
                centers[new_k] = temp_centers[1];
                radii[cluster] = temp_radii[0];
                radii[new_k] = temp_radii[1];
                new_k++;
        }
        lwfree(temp_centers);
        lwfree(temp_radii);
        lwfree(temp_clusters);
        lwfree(temp_objs);
        return new_k;
}

References kmeans(), lwalloc(), and lwfree().

Referenced by kmeans().

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