Add example for CSR graph

[SVN r31880]

doc/compressed_sparse_row.html

@@ -77,6 +77,8 @@ function address(host, user) {
           <li><a href="#edge-access">Edge access</a></li>
           <li><a href="#property-map-accessors">Property map accessors</a></li>
         </ul></li>
+
+      <li><a href="#example">Example</a></li>
     </ul>
 
     <a name="synopsis"></a><h2>Synopsis</h2>
@@ -586,6 +588,54 @@ void set_property(const compressed_sparse_row_graph&amp; g, GraphPropertyTag,
       is attached to the graph object <tt>g</tt>.
     </p>
 
+    <hr></hr>
+    <a name="example"></a><h2>Example</h2>
+
+    <br>[<a
+    href="../example/csr-example.cpp">libs/graph/example/csr-example.cpp</a>]
+
+    <p>We will use the <tt>compressed_sparse_row_graph</tt> graph
+    class to store a simple Web graph. In this web graph the vertices
+    represent web pages and the edges represent links from one web
+    page to another. With each web page we want to associate a URL, so
+    we initially create a <tt>WebPage</tt> class that stores the
+    URL. Then we can create our graph type by providing
+    <tt>WebPage</tt> as a parameter to the
+    <tt>compressed_sparse_row_graph</tt> class template.</p>
+
+    <pre>
+class WebPage
+{
+ public:
+  std::string url;
+};
+
+// ...
+
+typedef compressed_sparse_row_graph&lt;WebPage&gt; WebGraph;
+WebGraph g(&the_edges[0], &the_edges[0] + sizeof(the_edges)/sizeof(E), 6);
+    </pre>
+
+    <p>We can then set the properties on the vertices of the graph
+    using the <a href="bundles.html">bundled properties</a> syntax,
+    and display the edges for the user.</p>
+
+    <pre>
+// Set the URLs of each vertex
+int index = 0;
+BGL_FORALL_VERTICES(v, g, WebGraph)
+  g[v].url = urls[index++];
+
+// Output each of the links
+std::cout &lt;&lt; "The web graph:" &lt;&lt; std::endl;
+BGL_FORALL_EDGES(e, g, WebGraph)
+  std::cout &lt;&lt; "  " &lt;&lt; g[source(e, g)].url &lt;&lt; " -> " &lt;&lt; g[target(e, g)].url 
+            &lt;&lt; std::endl;
+    </pre>
+
+    <p>See the <a href="../example/csr-example.cpp">complete example
+    source</a> for other operations one can perform with a
+    <tt>compressed_sparse_row_graph</tt>.</p>
 <br>
 <HR>
 <TABLE>

example/csr-example.cpp

@@ -0,0 +1,60 @@
+// Copyright 2005 The Trustees of Indiana University.
+
+// Use, modification and distribution is subject to the Boost Software
+// License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+//  Authors: Douglas Gregor
+//           Andrew Lumsdaine
+#include <boost/graph/compressed_sparse_row_graph.hpp>
+#include <string>
+#include <boost/graph/iteration_macros.hpp>
+#include <iostream>
+#include <fstream>
+#include <boost/graph/graphviz.hpp>
+
+using namespace boost;
+
+class WebPage
+{
+ public:
+  std::string url;
+};
+
+int main()
+{
+  typedef std::pair<int, int> E;
+  const char* urls[6] = {
+    "http://www.boost.org/libs/graph/doc/index.html",
+    "http://www.boost.org/libs/graph/doc/table_of_contents.html",
+    "http://www.boost.org/libs/graph/doc/adjacency_list.html",
+    "http://www.boost.org/libs/graph/doc/history.html",
+    "http://www.boost.org/libs/graph/doc/bundles.html",
+    "http://www.boost.org/libs/graph/doc/using_adjacency_list.html",
+  };
+
+  E the_edges[] = { E(0, 1), E(0, 2), E(0, 3), E(1, 0), E(1, 3), E(1, 5), 
+                    E(2, 0), E(2, 5), E(3, 1), E(3, 4), E(4, 1), E(5, 0), 
+                    E(5, 2) };
+
+  typedef compressed_sparse_row_graph<WebPage> WebGraph;
+  WebGraph g(&the_edges[0], &the_edges[0] + sizeof(the_edges)/sizeof(E), 6);
+  
+  // Set the URLs of each vertex
+  int index = 0;
+  BGL_FORALL_VERTICES(v, g, WebGraph)
+    g[v].url = urls[index++];
+
+  // Output each of the links
+  std::cout << "The web graph:" << std::endl;
+  BGL_FORALL_EDGES(e, g, WebGraph)
+    std::cout << "  " << g[source(e, g)].url << " -> " << g[target(e, g)].url 
+              << std::endl;
+    
+  // Output the graph in DOT format
+  dynamic_properties dp;
+  dp.property("label", get(&WebPage::url, g));
+  std::ofstream out("web-graph.dot");
+  write_graphviz(out, g, dp, std::string(), get(vertex_index, g));
+  return 0;
+}