COIN-OR::LEMON - Graph Library

source: lemon-0.x/demo/descriptor_map_demo.cc @ 2042:bdc953f2a449

Last change on this file since 2042:bdc953f2a449 was 1956:a055123339d5, checked in by Alpar Juttner, 15 years ago

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1/* -*- C++ -*-
2 *
3 * This file is a part of LEMON, a generic C++ optimization library
4 *
5 * Copyright (C) 2003-2006
6 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
7 * (Egervary Research Group on Combinatorial Optimization, EGRES).
8 *
9 * Permission to use, modify and distribute this software is granted
10 * provided that this copyright notice appears in all copies. For
11 * precise terms see the accompanying LICENSE file.
12 *
13 * This software is provided "AS IS" with no warranty of any kind,
14 * express or implied, and with no claim as to its suitability for any
15 * purpose.
16 *
17 */
18
19#include <lemon/list_graph.h>
20#include <lemon/graph_utils.h>
21#include <lemon/graph_writer.h>
22#include <lemon/xy.h>
23#include <lemon/graph_to_eps.h>
24
25#include <iostream>
26
27#include <cstdlib>
28#include <cmath>
29#include <ctime>
30
31using namespace lemon;
32
33// Special map type
34// It gives back a position for each node. The position of the nodes
35// are on the circle with the given center and radius.
36//
37// Because we use the descriptor map it will hold the proprty described above
38// even if a node added or deleted.
39template <typename Graph>
40class CircleMap {
41public:
42
43  typedef xy<double> Value;
44  typedef typename Graph::Node Key;
45
46  CircleMap(const Graph& _graph,
47            const Value& _center = Value(0.0, 0.0),
48            double _radius = 1.0)
49    : descriptor(_graph), center(_center), radius(_radius) {}
50
51  Value operator[](const Key& key) const {
52    double angle = descriptor[key] * 2 * M_PI
53      / (double)descriptor.inverse().size();
54    double x = std::cos(angle) * radius + center.x;
55    double y = std::sin(angle) * radius + center.y;
56    return Value(x, y);
57  }
58
59private:
60 
61  DescriptorMap<Graph, typename Graph::Node> descriptor;
62  Value center;
63  double radius;
64};
65
66int main() {
67  std::srand(std::time(0));
68  typedef ListGraph Graph;
69  typedef Graph::Node Node;
70  typedef Graph::Edge Edge;
71 
72  // Generating a graph
73
74  std::cout << "Generating graph: " << std::endl;
75
76  Graph graph;
77 
78  const int NODE = 16;
79  for (int i = 0; i < NODE; ++i) {
80    graph.addNode();
81  }
82
83  // Creating descriptor map and inverse
84  DescriptorMap<Graph, Node> nodeDesc(graph);
85  DescriptorMap<Graph, Node>::InverseMap nodeInv(nodeDesc);
86
87  // Adding edges
88  // The descriptor map always maps an integer value for each node.
89  // The range of the values is always [0..n - 1] where n is the
90  // number of the nodes of the graph. The inverse map gives back the
91  // the node by its descriptor value.
92  //
93  // The inversemap cannot works without its DescriptorMap because
94  // it holds reference to it.
95  const int EDGE = (int)(NODE * std::log(double(NODE)));
96  for (int i = 0; i < EDGE; ++i) {
97    int si = (int)(std::rand() / (RAND_MAX + 1.0) * NODE);
98    int ti = (int)(std::rand() / (RAND_MAX + 1.0) * NODE);
99     
100    graph.addEdge(nodeInv[si], nodeInv[ti]);
101  }
102
103  GraphWriter<Graph>(std::cout, graph).run();
104
105  std::cout << std::endl;
106  std::cout << "Postscript file: descriptor_map_demo.eps" << std::endl;
107
108  // Make postscript from the graph.
109   
110  CircleMap<Graph> coords(graph, xy<double>(0.0, 0.0), 10.0);
111   
112  graphToEps(graph,"descriptor_map_demo.eps").scaleToA4().
113    title("Generated graph").
114    copyright("(C) 2006 LEMON Project").
115    coords(coords).
116    nodeScale(1.0).
117    enableParallel().parEdgeDist(1).
118    drawArrows().arrowWidth(1).arrowLength(1).
119    run();
120 
121  return 0;
122}
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