lgf_demo.cc File Reference

Detailed Description

This program gives an example of how to read and write a digraph and additional maps from/to a stream or a file using the LGF format.

The "digraph.lgf" file:

@nodes
label
0
1
2
3
4
5
6
7
@arcs
                label capacity
0       1       0         16
0       2       1         12
0       3       2         20
1       2       3         10
1       4       4         10
1       5       5         13
2       3       6         10
2       4       7         8
2       6       8         8
5       3       9         20
3       6       10        25
4       7       11        15
5       7       12        15
6       7       13        18
@attributes
source 0
target 7

And the program which reads it and prints the digraph to the standard output:

/* -*- mode: C++; indent-tabs-mode: nil; -*-
 *
 * This file is a part of LEMON, a generic C++ optimization library.
 *
 * Copyright (C) 2003-2009
 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
 * (Egervary Research Group on Combinatorial Optimization, EGRES).
 *
 * Permission to use, modify and distribute this software is granted
 * provided that this copyright notice appears in all copies. For
 * precise terms see the accompanying LICENSE file.
 *
 * This software is provided "AS IS" with no warranty of any kind,
 * express or implied, and with no claim as to its suitability for any
 * purpose.
 *
 */


#include <iostream>
#include <lemon/smart_graph.h>
#include <lemon/lgf_reader.h>
#include <lemon/lgf_writer.h>

using namespace lemon;

int main() {
  SmartDigraph g;
  SmartDigraph::ArcMap<int> cap(g);
  SmartDigraph::Node s, t;

  try {
    digraphReader(g, "digraph.lgf"). // read the directed graph into g
      arcMap("capacity", cap).       // read the 'capacity' arc map into cap
      node("source", s).             // read 'source' node to s
      node("target", t).             // read 'target' node to t
      run();
  } catch (Exception& error) { // check if there was any error
    std::cerr << "Error: " << error.what() << std::endl;
    return -1;
  }

  std::cout << "A digraph is read from 'digraph.lgf'." << std::endl;
  std::cout << "Number of nodes: " << countNodes(g) << std::endl;
  std::cout << "Number of arcs: " << countArcs(g) << std::endl;

  std::cout << "We can write it to the standard output:" << std::endl;

  digraphWriter(g).                // write g to the standard output
    arcMap("capacity", cap).       // write cap into 'capacity'
    node("source", s).             // write s to 'source'
    node("target", t).             // write t to 'target'
    run();

  return 0;
}

#include <iostream>
#include <lemon/smart_graph.h>
#include <lemon/lgf_reader.h>
#include <lemon/lgf_writer.h>