1<?xml version="1.0" encoding="utf-8" ?> 2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 3<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> 4<head> 5<meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> 6<meta name="generator" content="Docutils 0.6: http://docutils.sourceforge.net/" /> 7<title>Boost read_graphml</title> 8<link rel="stylesheet" href="../../../rst.css" type="text/css" /> 9</head> 10<body> 11<div class="document" id="logo-read-graphml"> 12<h1 class="title"><a class="reference external" href="../../../index.htm"><img align="middle" alt="Boost" class="align-middle" src="../../../boost.png" /></a> <tt class="docutils literal"><span class="pre">read_graphml</span></tt></h1> 13 14<!-- Copyright (C) 2006 Tiago de Paula Peixoto <tiago@forked.de> 15 16Distributed under the Boost Software License, Version 1.0. (See 17accompanying file LICENSE_1_0.txt or copy at 18http://www.boost.org/LICENSE_1_0.txt) 19 20Authors: Tiago de Paula Peixoto --> 21<pre class="literal-block"> 22void read_graphml(std::istream& in, MutableGraph& graph, 23 dynamic_properties& dp, size_t graph_index = 0); 24</pre> 25<p>The <tt class="docutils literal"><span class="pre">read_graphml</span></tt> function interprets a graph described using the 26<a class="reference external" href="http://graphml.graphdrawing.org/">GraphML</a> format and builds a BGL graph that captures that 27description. Using this function, you can initialize a graph using 28data stored as text.</p> 29<p>The GraphML format can specify both directed and undirected graphs, and 30<tt class="docutils literal"><span class="pre">read_graphml</span></tt> differentiates between the two. One must pass 31<tt class="docutils literal"><span class="pre">read_graphml</span></tt> an undirected graph when reading an undirected graph; 32the same is true for directed graphs. Furthermore, <tt class="docutils literal"><span class="pre">read_graphml</span></tt> 33will throw an exception if it encounters parallel edges and cannot add 34them to the graph.</p> 35<p>To handle attributes expressed in the GraphML format, <tt class="docutils literal"><span class="pre">read_graphml</span></tt> 36takes a <a class="reference external" href="../../property_map/doc/dynamic_property_map.html">dynamic_properties</a> object and operates on its collection of 37property maps. The reader passes all the properties encountered to 38this object, using the GraphML attribute names as the property names, 39and with the appropriate C++ value type based on the GraphML attribute type 40definition. Graph properties are also set with the same 41<a class="reference external" href="../../property_map/doc/dynamic_property_map.html">dynamic_properties</a> object, where the key type is the type of the graph itself.</p> 42<p>If the file contains multiple graphs, the <tt class="docutils literal"><span class="pre">graph_index</span></tt> parameter controls 43which graph will be loaded. It defaults to <tt class="docutils literal"><span class="pre">0</span></tt>, meaning that the first graph 44in the file will be loaded. If <tt class="docutils literal"><span class="pre">graph_index</span></tt> is greater than or equal to the 45number of graphs in the file, an empty graph will be returned.</p> 46<dl class="docutils"> 47<dt>Requirements:</dt> 48<dd><ul class="first last simple"> 49<li>The type of the graph must model the <a class="reference external" href="MutableGraph.html">Mutable Graph</a> concept.</li> 50<li>The type of the iterator must model the <a class="reference external" href="../../iterator/index.html">Multi-Pass Iterator</a> 51concept.</li> 52<li>The property map value types must be default-constructible.</li> 53</ul> 54</dd> 55</dl> 56<div class="contents topic" id="contents"> 57<p class="topic-title first">Contents</p> 58<ul class="simple"> 59<li><a class="reference internal" href="#where-defined" id="id2">Where Defined</a></li> 60<li><a class="reference internal" href="#exceptions" id="id3">Exceptions</a></li> 61<li><a class="reference internal" href="#building-the-graphml-reader" id="id4">Building the GraphML reader</a></li> 62<li><a class="reference internal" href="#notes" id="id5">Notes</a></li> 63<li><a class="reference internal" href="#see-also" id="id6">See Also</a></li> 64</ul> 65</div> 66<div class="section" id="where-defined"> 67<h1><a class="toc-backref" href="#id2">Where Defined</a></h1> 68<p><tt class="docutils literal"><span class="pre"><boost/graph/graphml.hpp></span></tt></p> 69</div> 70<div class="section" id="exceptions"> 71<h1><a class="toc-backref" href="#id3">Exceptions</a></h1> 72<pre class="literal-block"> 73struct graph_exception : public std::exception { 74 virtual ~graph_exception() throw(); 75 virtual const char* what() const throw() = 0; 76}; 77 78struct bad_parallel_edge : public graph_exception { 79 std::string from; 80 std::string to; 81 82 bad_parallel_edge(const std::string&, const std::string&); 83 virtual ~bad_parallel_edge() throw(); 84 const char* what() const throw(); 85}; 86 87struct directed_graph_error : public graph_exception { 88 virtual ~directed_graph_error() throw(); 89 virtual const char* what() const throw(); 90}; 91 92struct undirected_graph_error : public graph_exception { 93 virtual ~undirected_graph_error() throw(); 94 virtual const char* what() const throw(); 95}; 96 97struct parse_error : public graph_exception { 98 parse_error(const std::string&); 99 virtual ~parse_error() throw() {} 100 virtual const char* what() const throw(); 101 std::string statement; 102 std::string error; 103}; 104</pre> 105<p>Under certain circumstances, <tt class="docutils literal"><span class="pre">read_graphml</span></tt> will throw one of the 106above exceptions. The three concrete exceptions can all be caught 107using the general <tt class="docutils literal"><span class="pre">graph_exception</span></tt> moniker when greater precision 108is not needed. In addition, all of the above exceptions derive from 109the standard <tt class="docutils literal"><span class="pre">std::exception</span></tt> for even more generalized error 110handling.</p> 111<p>The <tt class="docutils literal"><span class="pre">bad_parallel_edge</span></tt> exception is thrown when an attempt to add a 112parallel edge to the supplied MutableGraph fails. The GraphML format 113supports parallel edges, but some BGL-compatible graph types do not. 114One example of such a graph is <tt class="docutils literal"><span class="pre">boost::adjacency_list<setS,vecS></span></tt>, 115which allows at most one edge can between any two vertices.</p> 116<p>The <tt class="docutils literal"><span class="pre">directed_graph_error</span></tt> exception occurs when an undirected graph 117type is passed to <tt class="docutils literal"><span class="pre">read_graph</span></tt>, but the graph defined in the GraphML 118file contains at least one directed edge.</p> 119<p>The <tt class="docutils literal"><span class="pre">undirected_graph_error</span></tt> exception occurs when a directed graph 120type is passed to <tt class="docutils literal"><span class="pre">read_graph</span></tt>, but the graph defined in the GraphML 121file contains at least one undirected edge.</p> 122<p>The <tt class="docutils literal"><span class="pre">parse_error</span></tt> exception occurs when a syntax error is 123encountered in the GraphML file. The error string will contain the 124line and column where the error was encountered.</p> 125</div> 126<div class="section" id="building-the-graphml-reader"> 127<h1><a class="toc-backref" href="#id4">Building the GraphML reader</a></h1> 128<p>To use the GraphML reader, you will need to build and link against 129the "boost_graph" library. The library can be built by following the 130<a class="reference external" href="../../../more/getting_started.html#Build_Install">Boost Jam Build Instructions</a> for the subdirectory <tt class="docutils literal"><span class="pre">libs/graph/build</span></tt>.</p> 131</div> 132<div class="section" id="notes"> 133<h1><a class="toc-backref" href="#id5">Notes</a></h1> 134<blockquote> 135<ul class="simple"> 136<li>On successful reading of a graph, every vertex and edge will have 137an associated value for every respective edge and vertex property 138encountered while interpreting the graph. These values will be set 139using the <tt class="docutils literal"><span class="pre">dynamic_properties</span></tt> object. Some properties may be 140<tt class="docutils literal"><span class="pre">put</span></tt> multiple times during the course of reading in order to 141ensure the GraphML semantics. Those edges and vertices that are 142not explicitly given a value for a property (and that property has 143no default) will be given the default constructed value of the 144value type. <strong>Be sure that property map value types are default 145constructible.</strong></li> 146<li>Nested graphs are supported as long as they are exactly of the same 147type as the root graph, i.e., are also directed or undirected. Note 148that since nested graphs are not directly supported by BGL, they 149are in fact completely ignored when building the graph, and the 150internal vertices or edges are interpreted as belonging to the root 151graph.</li> 152<li>Hyperedges and Ports are not supported.</li> 153</ul> 154</blockquote> 155</div> 156<div class="section" id="see-also"> 157<h1><a class="toc-backref" href="#id6">See Also</a></h1> 158<p><a class="reference external" href="write_graphml.html">write_graphml</a></p> 159</div> 160</div> 161<div class="footer"> 162<hr class="footer" /> 163Generated on: 2012-11-12 22:25 UTC. 164Generated by <a class="reference external" href="http://docutils.sourceforge.net/">Docutils</a> from <a class="reference external" href="http://docutils.sourceforge.net/rst.html">reStructuredText</a> source. 165 166</div> 167</body> 168</html> 169
