doc/lgf.dox
author Alpar Juttner <alpar@cs.elte.hu>
Sun, 14 Mar 2010 09:13:04 +0100
changeset 865 d48d79b11f5b
parent 313 64f8f7cc6168
child 923 c8c8801db0a4
permissions -rw-r--r--
Replace figure at matching doc #348

The original bibartite_matching.eps is kept for future use.
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/* -*- mode: C++; indent-tabs-mode: nil; -*-
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 *
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 * This file is a part of LEMON, a generic C++ optimization library.
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 *
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 * Copyright (C) 2003-2009
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 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
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 * (Egervary Research Group on Combinatorial Optimization, EGRES).
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 *
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 * Permission to use, modify and distribute this software is granted
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 * provided that this copyright notice appears in all copies. For
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 * precise terms see the accompanying LICENSE file.
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 *
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 * This software is provided "AS IS" with no warranty of any kind,
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 * express or implied, and with no claim as to its suitability for any
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 * purpose.
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 *
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 */
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namespace lemon {
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/*!
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\page lgf-format LEMON Graph Format (LGF)
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The \e LGF is a <em>column oriented</em>
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file format for storing graphs and associated data like
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node and edge maps.
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Each line with \c '#' first non-whitespace
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character is considered as a comment line.
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Otherwise the file consists of sections starting with
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a header line. The header lines starts with an \c '@' character followed by the
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type of section. The standard section types are \c \@nodes, \c
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\@arcs and \c \@edges
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and \@attributes. Each header line may also have an optional
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\e name, which can be use to distinguish the sections of the same
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type.
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The standard sections are column oriented, each line consists of
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<em>token</em>s separated by whitespaces. A token can be \e plain or
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\e quoted. A plain token is just a sequence of non-whitespace characters,
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while a quoted token is a
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character sequence surrounded by double quotes, and it can also
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contain whitespaces and escape sequences.
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The \c \@nodes section describes a set of nodes and associated
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maps. The first is a header line, its columns are the names of the
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maps appearing in the following lines.
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One of the maps must be called \c
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"label", which plays special role in the file.
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The following
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non-empty lines until the next section describes nodes of the
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graph. Each line contains the values of the node maps
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associated to the current node.
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\code
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 @nodes
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 label  coordinates  size    title
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 1      (10,20)      10      "First node"
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 2      (80,80)      8       "Second node"
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 3      (40,10)      10      "Third node"
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\endcode
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The \c \@arcs section is very similar to the \c \@nodes section,
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it again starts with a header line describing the names of the maps,
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but the \c "label" map is not obligatory here. The following lines
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describe the arcs. The first two tokens of each line are
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the source and the target node of the arc, respectively, then come the map
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values. The source and target tokens must be node labels.
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\code
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 @arcs
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         capacity
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 1   2   16
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 1   3   12
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 2   3   18
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\endcode
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The \c \@edges is just a synonym of \c \@arcs. The \@arcs section can
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also store the edge set of an undirected graph. In such case there is
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a conventional method for store arc maps in the file, if two columns
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has the same caption with \c '+' and \c '-' prefix, then these columns
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can be regarded as the values of an arc map.
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The \c \@attributes section contains key-value pairs, each line
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consists of two tokens, an attribute name, and then an attribute
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value. The value of the attribute could be also a label value of a
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node or an edge, or even an edge label prefixed with \c '+' or \c '-',
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which regards to the forward or backward directed arc of the
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corresponding edge.
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\code
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 @attributes
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 source 1
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 target 3
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 caption "LEMON test digraph"
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\endcode
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The \e LGF can contain extra sections, but there is no restriction on
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the format of such sections.
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*/
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}
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//  LocalWords:  whitespace whitespaces