www.pudn.com > CVPR12_SAS_code.zip > segment-graph.h, change:2006-12-28,size:2191b

```/*

This program is free software; you can redistribute it and/or modify
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
*/

#ifndef SEGMENT_GRAPH
#define SEGMENT_GRAPH

#include <algorithm>
#include <cmath>
#include "disjoint-set.h"

// threshold function
#define THRESHOLD(size, c) (c/size)

typedef struct {
float w;
int a, b;
} edge;

bool operator<(const edge &a, const edge &b) {
return a.w < b.w;
}

/*
* Segment a graph
*
* Returns a disjoint-set forest representing the segmentation.
*
* num_vertices: number of vertices in graph.
* num_edges: number of edges in graph
* edges: array of edges.
* c: constant for treshold function.
*/
universe *segment_graph(int num_vertices, int num_edges, edge *edges,
float c) {
// sort edges by weight
std::sort(edges, edges + num_edges);

// make a disjoint-set forest
universe *u = new universe(num_vertices);

// init thresholds
float *threshold = new float[num_vertices];
for (int i = 0; i < num_vertices; i++)
threshold[i] = THRESHOLD(1,c);

// for each edge, in non-decreasing weight order...
for (int i = 0; i < num_edges; i++) {
edge *pedge = &edges[i];

// components conected by this edge
int a = u->find(pedge->a);
int b = u->find(pedge->b);
if (a != b) {
if ((pedge->w <= threshold[a]) &&
(pedge->w <= threshold[b])) {
u->join(a, b);
a = u->find(a);
threshold[a] = pedge->w + THRESHOLD(u->size(a), c);
}
}
}

// free up
delete threshold;
return u;
}

#endif
```