Changeset 1584:cf4bc8d477f4 in lemon-0.x

Timestamp:

07/22/05 18:57:07 (19 years ago)

Author:

zsuzska

Branch:

default

Phase:

public

Convert:

svn:c9d7d8f5-90d6-0310-b91f-818b3a526b0e/lemon/trunk@2087

Message:

corrections

Files:

• demo/kruskal_demo.cc (modified) (1 diff)
• doc/quicktour.dox (modified) (1 diff)

demo/kruskal_demo.cc

@@ -61 +61 @@
   Edge e10 = g.addEdge(v4, t);
 
-  //Make the input and output for the kruskal.
+  //Make the input for the kruskal.
   typedef ListGraph::EdgeMap<int> ECostMap;
+  ECostMap edge_cost_map(g);
+
+  // Fill the edge_cost_map. 
+  edge_cost_map.set(e1, -10);
+  edge_cost_map.set(e2, -9);
+  edge_cost_map.set(e3, -8);
+  edge_cost_map.set(e4, -7);
+  edge_cost_map.set(e5, -6);
+  edge_cost_map.set(e6, -5);
+  edge_cost_map.set(e7, -4);
+  edge_cost_map.set(e8, -3);
+  edge_cost_map.set(e9, -2);
+  edge_cost_map.set(e10, -1);
+
+  // Make the map or the vector, which will contain the edges of the minimum
+  // spanning tree.
+
   typedef ListGraph::EdgeMap<bool> EBoolMap;
-
-  ECostMap edge_cost_map(g, 2);
   EBoolMap tree_map(g);
-
-  // Kruskal.
-  std::cout << "The weight of the minimum spanning tree by using Kruskal algorithm is " 
-            << kruskal(g, ConstMap<ListGraph::Edge,int>(2), tree_map)<<std::endl;
-
-  //Make another input (non-uniform costs) for the kruskal.
-  ECostMap edge_cost_map_2(g);
-  edge_cost_map_2.set(e1, -10);
-  edge_cost_map_2.set(e2, -9);
-  edge_cost_map_2.set(e3, -8);
-  edge_cost_map_2.set(e4, -7);
-  edge_cost_map_2.set(e5, -6);
-  edge_cost_map_2.set(e6, -5);
-  edge_cost_map_2.set(e7, -4);
-  edge_cost_map_2.set(e8, -3);
-  edge_cost_map_2.set(e9, -2);
-  edge_cost_map_2.set(e10, -1);
 
   vector<Edge> tree_edge_vec;
 
-  //Test with non uniform costs and inserter.
-  std::cout << "The weight of the minimum spanning tree with non-uniform costs is " << 
-    kruskal(g, edge_cost_map_2, std::back_inserter(tree_edge_vec)) <<std::endl;
 
-  //The vector for the edges of the output tree.
-  tree_edge_vec.clear();
+  //Kruskal Algorithm.  
 
-  //Test with makeKruskalMapInput and makeKruskalSequenceOutput.
+  //Input: a graph (g); a costmap of the graph (edge_cost_map); a
+  //boolmap (tree_map) or a vector (tree_edge_vec) to store the edges
+  //of the output tree;
 
-  std::cout << "The weight of the minimum spanning tree again is " << 
-   kruskal(g,makeKruskalMapInput(g,edge_cost_map_2),makeKruskalSequenceOutput(std::back_inserter(tree_edge_vec)))<< std::endl;
+  //Output: it gives back the value of the minimum spanning tree, and
+  //set true for the edges of the tree in the edgemap tree_map or
+  //store the edges of the tree in the vector tree_edge_vec;
 
 
+  // Kruskal with boolmap;
+  std::cout << "The weight of the minimum spanning tree is " << 
+    kruskal(g, edge_cost_map, tree_map)<<std::endl;
+
+  int k=0;
+  std::cout << "The edges of the tree:" ;
+  for(EdgeIt i(g); i!=INVALID; ++i){
+
+    if (tree_map[i]) { 
+      std::cout << g.id(i) <<";";
+      ++k;
+    }
+  }
+  std::cout << std::endl;
+  std::cout << "The size of the tree is: "<< k << std::endl;
+
+
+  // Kruskal with vector;
+  std::cout << "The weight of the minimum spanning tree again is " << 
+    kruskal(g, edge_cost_map, std::back_inserter(tree_edge_vec)) <<std::endl;
+
+
+
+  std::cout << "The edges of the tree again: " ;
+  for(int i=tree_edge_vec.size()-1; i>=0;  i--)
+    std::cout << g.id(tree_edge_vec[i]) << ";" ;
+  std::cout << std::endl;
+  std::cout << "The size of the tree again is: "<< tree_edge_vec.size()<< std::endl; 
+
+  
   return 0;
 }

doc/quicktour.dox

@@ -144 +144 @@
 length of wires then you might be looking for a <b>minimum spanning
 tree</b> in an undirected graph. This can be found using the Kruskal
-algorithm: the function \ref lemon::kruskal "LEMON Kruskal " does
-this job for you.  After we had a graph \c g and a cost map \c
-edge_cost_map , the following code fragment shows an example how to get weight of the minmum spanning tree (in this first example the costs are uniform; this is of course not the case in real life applications):
+algorithm: the function \ref lemon::kruskal "LEMON Kruskal " does this
+job for you.  
+
+First make a graph \c g and a cost map \c
+edge_cost_map, then make a bool edgemap \c tree_map or a vector \c
+tree_edge_vec for the algorithm output. After calling the function it
+gives back the weight of the minimum spanning tree and the \c tree_map or
+the \c tree_edge_vec contains the edges of the tree.
+
+If you want to store the edges in a bool edgemap, then use the
+function as follows:
 
 \dontinclude kruskal_demo.cc
-\skip std::cout 
-\until kruskal
-
-In the variable \c tree_map the function gives back an edge bool map, which contains the edges of the found tree.
-
-If the costs are non-uniform, for example  the cost is given by \c
-edge_cost_map_2 , or the edges of the tree  have to be given in a
-vector, then we can give to the kruskal a vector \c tree_edge_vec , instead of
-an edge bool map:
-
-\skip edge_cost_map_2 
-\until edge_cost_map_2, std::back_inserter
-
-And finally the next fragment shows how to use the functions \c makeKruskalMapInput and \c makeKruskalSequenceOutPut:
-
-\skip makeKruskalSequenceOutput
-\until tree_edge_vec
+\skip Kruskal with boolmap; 
+\until  std::endl
+
+And if you rather use a vector instead of a bool map:
+
+\skip Kruskal with vector; 
+\until std::endl
 
 See the whole program in \ref kruskal_demo.cc.