| 1 | /* -*- mode: C++; indent-tabs-mode: nil; -*- |
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| 2 | * |
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| 3 | * This file is a part of LEMON, a generic C++ optimization library. |
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| 4 | * |
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| 5 | * Copyright (C) 2003-2009 |
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| 6 | * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport |
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| 7 | * (Egervary Research Group on Combinatorial Optimization, EGRES). |
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| 8 | * |
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| 9 | * Permission to use, modify and distribute this software is granted |
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| 10 | * provided that this copyright notice appears in all copies. For |
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| 11 | * precise terms see the accompanying LICENSE file. |
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| 12 | * |
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| 13 | * This software is provided "AS IS" with no warranty of any kind, |
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| 14 | * express or implied, and with no claim as to its suitability for any |
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| 15 | * purpose. |
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| 16 | * |
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| 17 | */ |
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| 18 | |
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| 19 | namespace lemon { |
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| 20 | /*! |
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| 21 | |
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| 22 | |
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| 23 | |
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| 24 | \page lgf-format LEMON Graph Format (LGF) |
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| 25 | |
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| 26 | The \e LGF is a <em>column oriented</em> |
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| 27 | file format for storing graphs and associated data like |
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| 28 | node and edge maps. |
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| 29 | |
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| 30 | Each line with \c '#' first non-whitespace |
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| 31 | character is considered as a comment line. |
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| 32 | |
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| 33 | Otherwise the file consists of sections starting with |
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| 34 | a header line. The header lines starts with an \c '@' character followed by the |
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| 35 | type of section. The standard section types are \c \@nodes, \c |
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| 36 | \@arcs and \c \@edges |
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| 37 | and \@attributes. Each header line may also have an optional |
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| 38 | \e name, which can be use to distinguish the sections of the same |
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| 39 | type. |
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| 40 | |
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| 41 | The standard sections are column oriented, each line consists of |
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| 42 | <em>token</em>s separated by whitespaces. A token can be \e plain or |
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| 43 | \e quoted. A plain token is just a sequence of non-whitespace characters, |
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| 44 | while a quoted token is a |
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| 45 | character sequence surrounded by double quotes, and it can also |
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| 46 | contain whitespaces and escape sequences. |
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| 47 | |
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| 48 | The \c \@nodes section describes a set of nodes and associated |
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| 49 | maps. The first is a header line, its columns are the names of the |
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| 50 | maps appearing in the following lines. |
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| 51 | One of the maps must be called \c |
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| 52 | "label", which plays special role in the file. |
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| 53 | The following |
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| 54 | non-empty lines until the next section describes nodes of the |
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| 55 | graph. Each line contains the values of the node maps |
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| 56 | associated to the current node. |
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| 57 | |
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| 58 | \code |
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| 59 | @nodes |
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| 60 | label coordinates size title |
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| 61 | 1 (10,20) 10 "First node" |
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| 62 | 2 (80,80) 8 "Second node" |
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| 63 | 3 (40,10) 10 "Third node" |
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| 64 | \endcode |
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| 65 | |
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| 66 | The \e LGF files can also contain bipartite graphs, in this case a |
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| 67 | \c @red_nodes and a \c @blue_nodes sections describe the node set of the |
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| 68 | graph. If a map is in both of these sections, then it can be used as a |
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| 69 | regular node map. |
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| 70 | |
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| 71 | \code |
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| 72 | @red_nodes |
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| 73 | label only_red_map name |
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| 74 | 1 "cherry" "John" |
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| 75 | 2 "Santa Claus" "Jack" |
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| 76 | 3 "blood" "Jason" |
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| 77 | @blue_nodes |
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| 78 | label name |
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| 79 | 4 "Elisabeth" |
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| 80 | 5 "Eve" |
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| 81 | \endcode |
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| 82 | |
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| 83 | The \c \@arcs section is very similar to the \c \@nodes section, |
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| 84 | it again starts with a header line describing the names of the maps, |
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| 85 | but the \c "label" map is not obligatory here. The following lines |
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| 86 | describe the arcs. The first two tokens of each line are |
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| 87 | the source and the target node of the arc, respectively, then come the map |
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| 88 | values. The source and target tokens must be node labels. |
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| 89 | |
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| 90 | \code |
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| 91 | @arcs |
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| 92 | capacity |
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| 93 | 1 2 16 |
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| 94 | 1 3 12 |
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| 95 | 2 3 18 |
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| 96 | \endcode |
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| 97 | |
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| 98 | If there is no map in the \c \@arcs section at all, then it must be |
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| 99 | indicated by a sole '-' sign in the first line. |
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| 100 | |
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| 101 | \code |
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| 102 | @arcs |
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| 103 | - |
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| 104 | 1 2 |
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| 105 | 1 3 |
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| 106 | 2 3 |
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| 107 | \endcode |
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| 108 | |
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| 109 | The \c \@edges is just a synonym of \c \@arcs. The \@arcs section can |
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| 110 | also store the edge set of an undirected graph. In such case there is |
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| 111 | a conventional method for store arc maps in the file, if two columns |
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| 112 | have the same caption with \c '+' and \c '-' prefix, then these columns |
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| 113 | can be regarded as the values of an arc map. |
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| 114 | |
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| 115 | The \c \@attributes section contains key-value pairs, each line |
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| 116 | consists of two tokens, an attribute name, and then an attribute |
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| 117 | value. The value of the attribute could be also a label value of a |
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| 118 | node or an edge, or even an edge label prefixed with \c '+' or \c '-', |
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| 119 | which regards to the forward or backward directed arc of the |
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| 120 | corresponding edge. |
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| 121 | |
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| 122 | \code |
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| 123 | @attributes |
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| 124 | source 1 |
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| 125 | target 3 |
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| 126 | caption "LEMON test digraph" |
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| 127 | \endcode |
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| 128 | |
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| 129 | The \e LGF can contain extra sections, but there is no restriction on |
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| 130 | the format of such sections. |
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| 131 | |
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| 132 | */ |
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| 133 | } |
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| 134 | |
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| 135 | // LocalWords: whitespace whitespaces |
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