# source:lemon/doc/lgf.dox@1071:2d583da4ba40

1.1
Last change on this file since 1071:2d583da4ba40 was 1069:b1b534ddb539, checked in by Alpar Juttner <alpar@…>, 10 years ago

Merge #382 to branch 1.1

File size: 3.6 KB
RevLine
[209]1/* -*- mode: C++; indent-tabs-mode: nil; -*-
[156]2 *
[209]3 * This file is a part of LEMON, a generic C++ optimization library.
[156]4 *
[463]5 * Copyright (C) 2003-2009
[156]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
19namespace lemon {
20/*!
21
22
23
[236]24\page lgf-format LEMON Graph Format (LGF)
[156]25
26The \e LGF is a <em>column oriented</em>
27file format for storing graphs and associated data like
28node and edge maps.
29
30Each line with \c '#' first non-whitespace
31character is considered as a comment line.
32
33Otherwise the file consists of sections starting with
34a header line. The header lines starts with an \c '@' character followed by the
35type of section. The standard section types are \c \@nodes, \c
36\@arcs and \c \@edges
37and \@attributes. Each header line may also have an optional
38\e name, which can be use to distinguish the sections of the same
39type.
40
41The standard sections are column oriented, each line consists of
42<em>token</em>s separated by whitespaces. A token can be \e plain or
43\e quoted. A plain token is just a sequence of non-whitespace characters,
44while a quoted token is a
45character sequence surrounded by double quotes, and it can also
[209]46contain whitespaces and escape sequences.
[156]47
48The \c \@nodes section describes a set of nodes and associated
[192]49maps. The first is a header line, its columns are the names of the
[156]50maps appearing in the following lines.
51One of the maps must be called \c
52"label", which plays special role in the file.
53The following
54non-empty lines until the next section describes nodes of the
55graph. Each line contains the values of the node maps
56associated to the current node.
57
58\code
59 @nodes
[212]60 label  coordinates  size    title
61 1      (10,20)      10      "First node"
62 2      (80,80)      8       "Second node"
63 3      (40,10)      10      "Third node"
[156]64\endcode
65
[1067]66The \c \@arcs section is very similar to the \c \@nodes section, it
67again starts with a header line describing the names of the maps, but
68the \c "label" map is not obligatory here. The following lines
69describe the arcs. The first two tokens of each line are the source
70and the target node of the arc, respectively, then come the map
[156]71values. The source and target tokens must be node labels.
72
73\code
74 @arcs
[212]75         capacity
[156]76 1   2   16
77 1   3   12
78 2   3   18
79\endcode
80
[1067]81If there is no map in the \c \@arcs section at all, then it must be
82indicated by a sole '-' sign in the first line.
83
84\code
85 @arcs
86         -
87 1   2
88 1   3
89 2   3
90\endcode
91
[313]92The \c \@edges is just a synonym of \c \@arcs. The \@arcs section can
[201]93also store the edge set of an undirected graph. In such case there is
94a conventional method for store arc maps in the file, if two columns
[1067]95have the same caption with \c '+' and \c '-' prefix, then these columns
[201]96can be regarded as the values of an arc map.
[156]97
98The \c \@attributes section contains key-value pairs, each line
[201]99consists of two tokens, an attribute name, and then an attribute
100value. The value of the attribute could be also a label value of a
101node or an edge, or even an edge label prefixed with \c '+' or \c '-',
102which regards to the forward or backward directed arc of the
103corresponding edge.
[156]104
105\code
106 @attributes
107 source 1
108 target 3
109 caption "LEMON test digraph"
110\endcode
111
[162]112The \e LGF can contain extra sections, but there is no restriction on
113the format of such sections.
114
[156]115*/
116}
117
118//  LocalWords:  whitespace whitespaces
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