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<Head>
<Title>Boost Graph Library: Edge List Class</Title>
<BODY BGCOLOR="#ffffff" LINK="#0000ee" TEXT="#000000" VLINK="#551a8b"
ALINK="#ff0000">
<IMG SRC="../../../boost.png"
ALT="C++ Boost" width="277" height="86">
<BR Clear>
<H1><A NAME="sec:edge-list-class"></A>
<PRE>
edge_list<EdgeIterator, ValueType, DiffType>
</PRE>
</H1>
<P>
The <TT>edge_list</TT> class is an adaptor that turns a pair of edge
iterators into a class that models <TT>EdgeListGraph</TT>. The
<TT>value_type</TT> of the edge iterator must be a <TT>std::pair</TT> (or
at least have <TT>first</TT> and <TT>second</TT> members). The
<TT>first_type</TT> and <TT>second_type</TT> of the pair must be the
same and they will be used for the graph's <TT>vertex_descriptor</TT>.
The <TT>ValueType</TT> and <TT>DiffType</TT> template parameters are only
needed if your compiler does not support partial
specialization. Otherwise they default to the correct types.
<P>
<H3>Example</H3>
<P>
Applying the Bellman-Ford shortest paths algorithm to an
<TT>edge_list</TT>.
<P>
<PRE>
enum { u, v, x, y, z, N };
char name[] = { 'u', 'v', 'x', 'y', 'z' };
typedef std::pair<int,int> E;
E edges[] = { E(u,y), E(u,x), E(u,v),
E(v,u),
E(x,y), E(x,v),
E(y,v), E(y,z),
E(z,u), E(z,x) };
int weight[] = { -4, 8, 5,
-2,
9, -3,
7, 2,
6, 7 };
typedef boost::edge_list<E*> Graph;
Graph g(edges, edges + sizeof(edges) / sizeof(E));
std::vector<int> distance(N, std::numeric_limits<short>::max());
std::vector<int> parent(N,-1);
distance[z] = 0;
parent[z] = z;
bool r = boost::bellman_ford_shortest_paths(g, int(N), weight,
distance.begin(),
parent.begin());
if (r)
for (int i = 0; i < N; ++i)
std::cout << name[i] << ": " << distance[i]
<< " " << name[parent[i]] << std::endl;
else
std::cout << "negative cycle" << std::endl;
</PRE>
The output is the distance from the root and the parent
of each vertex in the shortest paths tree.
<PRE>
u: 2 v
v: 4 x
x: 7 z
y: -2 u
z: 0 z
</PRE>
<P>
<p>
<H3>Where Defined</H3>
<a href="../../../boost/graph/edge_list.hpp"><TT>boost/graph/edge_list.hpp</TT></a>
<P>
<H3>Template Parameters</H3>
<P>
<TABLE border>
<TR>
<th>Parameter</th><th>Description</th>
</tr>
<TR><TD><TT>EdgeIterator</TT></TD> <TD>Must be model of <a
href="http://www.sgi.com/tech/stl/InputIterator.html">InputIterator</a>
who's <TT>value_type</TT> must be a pair of vertex descriptors.</TD>
</TR>
<TR><TD><TT>ValueType</TT></TD>
<TD>The <TT>value_type</TT> of the <TT>EdgeIterator</TT>.<br>
Default: <TT>std::iterator_traits<EdgeIterator>::value_type</TT></TD>
</TR>
<TR><TD><TT>DiffType</TT></TD>
<TD>The <TT>difference_type</TT> of the <TT>EdgeIterator</TT>.<br>
Default: <TT>std::iterator_traits<EdgeIterator>::difference_type</TT></TD>
</TR>
</TABLE>
<P>
<H3>Model of</H3>
<a href="./EdgeListGraph.html">EdgeListGraph</a>
<P>
<H3>Associated Types</H3>
<hr>
<tt>boost::graph_traits<edge_list>::vertex_descriptor</tt>
<br><br>
The type for the vertex descriptors associated with the
<TT>edge_list</TT>. This will be the same type as
<TT>std::iterator_traits<EdgeIterator>::value_type::first_type</TT>.
<hr>
<tt>
boost::graph_traits<edge_list>::edge_descriptor
</tt>
<br><br>
The type for the edge descriptors associated with the
<TT>edge_list</TT>.
<hr>
<tt>
boost::graph_traits<edge_list>::edge_iterator
</tt>
<br><br>
The type for the iterators returned by <TT>edges()</TT>. The iterator
category of the <TT>edge_iterator</TT> will be the same as that of the
<TT>EdgeIterator</TT>.
<hr>
<h3>Member Functions</h3>
<hr>
<tt>
edge_list(EdgeIterator first, EdgeIterator last)
</tt>
<br><br>
Creates a graph object with <TT>n</TT> vertices and with the
edges specified in the edge list given by the range <TT>[first,last)</TT>.
<hr>
<H3>Non-Member Functions</H3>
<hr>
<tt>
std::pair<edge_iterator, edge_iterator><br>
edges(const edge_list& g)
</tt>
<br><br>
Returns an iterator-range providing access to the edge set of graph <TT>g</TT>.
<hr>
<tt>
vertex_descriptor<br>
source(edge_descriptor e, const edge_list& g)
</tt>
<br><br>
Returns the source vertex of edge <TT>e</TT>.
<hr>
<tt>
vertex_descriptor<br>
target(edge_descriptor e, const edge_list& g)
</tt>
<br><br>
Returns the target vertex of edge <TT>e</TT>.
<hr>
<br>
<HR>
<TABLE>
<TR valign=top>
<TD nowrap>Copyright © 2000-2001</TD><TD>
<A HREF="../../../people/jeremy_siek.htm">Jeremy Siek</A>,
Indiana University (<A
HREF="mailto:jsiek@osl.iu.edu">jsiek@osl.iu.edu</A>)<br>
<A HREF="../../../people/liequan_lee.htm">Lie-Quan Lee</A>, Indiana University (<A HREF="mailto:llee@cs.indiana.edu">llee@cs.indiana.edu</A>)<br>
<A HREF=http://www.osl.iu.edu/~lums>Andrew Lumsdaine</A>,
Indiana University (<A
HREF="mailto:lums@osl.iu.edu">lums@osl.iu.edu</A>)
</TD></TR></TABLE>
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