Ideas on implementing graph in C++ - c++

Question

I need help to design the best data structure for a GRAPH. The following is my implementation.
Please give your thoughts on this design.
#ifndef _GRAPH_H_
#define _GRAPH_H_
#include <map>
#include <vector>
#include <iostream>
#include <list>
template <typename T>
class Vertex {
public:
Vertex(){};
Vertex(T inVertex): m_vertex(inVertex), m_visited(false){}
~Vertex(){}
bool operator<(const Vertex<T>& right) const { return m_vertex < right.m_vertex;}
T getVertex () { return m_vertex;}
T getVisited () { return m_visited;}
T getParent () { return m_vertexParentVisited;}
void setVisited(bool inVisited) { m_visited = inVisited;}
void setParent(T inParentVertex) { m_vertexParentVisited = inParentVertex;}
private:
T m_vertex;
T m_vertexParentVisited;
bool m_visited;
};
template <typename T>
class Edge
{
public:
enum EDGE_TYPE
{
TREE_EDGE,
PARENT_EDGE,
BACK_EDGE,
DOWN_EDGE
};
Edge(Vertex<T>* inSrc, Vertex<T>* inDst)
{
m_SourceVertex = inSrc;
m_DestVertex = inDst;
}
void SetEdgeType( EDGE_TYPE t)
{
m_EdgeType = t;
}
private:
Vertex<T>* m_SourceVertex;
Vertex<T>* m_DestVertex;
EDGE_TYPE m_EdgeType;
protected:
};
template <typename T>
class Graph
{
public:
typedef Vertex<T> GraphVertex;
// Adjancency List Datastructure and Iterator declaration.
// Use STL List here
typedef std::list<GraphVertex*> AdjList;
typedef typename AdjList::iterator AdjListIterator;
// Graph Data structure declaration and Iterator declaration
// Graph is map of GraphVertex* and List of adjacency list.
typedef std::map<GraphVertex*, AdjList> GraphMap;
typedef typename GraphMap::iterator GraphIterator;
// Graph Memory pool is map where actual memory allocation
// will happen.
// Make sure you have some way to identify each vertex.
// Map key is the identification method of the vertex.
// Map value is the pointer to actual object.
typedef std::map<T,GraphVertex*> GraphMemoryPool;
typedef typename GraphMemoryPool::iterator GraphInMemoryIterator;
// Edge Class Declaration.
typedef std::vector<Edge<T> > GraphEdge;
private:
bool m_isDirected;
GraphMap m_graph;
GraphMemoryPool m_graphMemoryPool;
std::vector<T> m_SearchOrderVector;
GraphEdge m_GraphEdge;
public:
Graph(bool inIsDirected):m_isDirected(inIsDirected) {}
~Graph()
{
for ( GraphInMemoryIterator itr = m_graphMemoryPool.begin(); itr != m_graphMemoryPool.end(); ++itr)
{
if ( itr->second) delete itr->second;
}
m_graphMemoryPool.clear();
m_graph.clear();
}
void insert(T inSRC, T inDST)
{
if ( m_isDirected)
{
__insert(inSRC,inDST);
}
else
{
__insert(inSRC,inDST);
__insert(inDST,inSRC);
}
}
void printGraph()
{
for ( GraphIterator itr = m_graph.begin(); itr != m_graph.end(); ++itr)
{
std::cout << static_cast<GraphVertex*>(itr->first)->getVertex() << " : ";
AdjList tmp = static_cast<AdjList>(itr->second);
for ( AdjListIterator itr1 = tmp.begin(); itr1 != tmp.end(); ++itr1)
{
std::cout << (*itr1)->getVertex() << " ";
}
std::cout << std::endl;
}
}
void printSearchOrder()
{
std::vector<T> tmp = getSearchOrderVector();
for ( vector<T>::iterator itr = tmp.begin(); itr != tmp.end(); ++itr)
{
std::cout << *itr << " ";
}
std::cout << std::endl;
}
void printParentLinkMap()
{
std::vector<T> tmp = getSearchOrderVector();
for ( vector<T>::iterator itr = tmp.begin(); itr != tmp.end(); ++itr)
{
GraphVertex *tmp = __VertexInstance(*itr);
std::cout << "[" << tmp->getParent() << "] Parent Of [" << tmp->getVertex() << "]" << std::endl;
}
}
void DFS()
{
for ( GraphInMemoryIterator itr = m_graphMemoryPool.begin(); itr != m_graphMemoryPool.end(); ++itr)
{
(*itr).second->setVisited(false);
}
m_SearchOrderVector.clear();
// This loop handles the case when the grpah is not
// Connected.
for ( GraphIterator itr = m_graph.begin(); itr != m_graph.end(); ++itr)
{
GraphVertex *currentVertex = static_cast<GraphVertex*>(itr->first);
if ( currentVertex->getVisited() == false)
{
T curVertex = currentVertex->getVertex();
// Insert new element in Search Order Vector.
m_SearchOrderVector.push_back(curVertex);
// Set the parent of this root node in the DFS search tree
currentVertex->setParent(curVertex);
// Create Edge with itself here.
__setTypeAndInsertNewEdge( curVertex,
curVertex,
Edge<T>::TREE_EDGE);
// Mark the vertex as visited.
currentVertex->setVisited(true);
__rundfs(itr);
}
}
}
std::vector<T> getSearchOrderVector() { return m_SearchOrderVector;}
int getNumberOfVertex(){ return (int)m_graph.size();}
private:
void __setTypeAndInsertNewEdge( T inSRC, T inDST, typename Edge<T>::EDGE_TYPE t )
{
Edge<T> tmp(__VertexInstance(inSRC),
__VertexInstance(inDST));
tmp.SetEdgeType(t);
m_GraphEdge.push_back(tmp);
}
// Recursive DFS function.
// Apart from visiting vertices
// this implementatioin will be doing following.
// 1. Maintain the order in which vertices are visited.
// 2. Update Parent link map
// 3. Create Edge and update the type of the edge.
void __rundfs( typename GraphMap::iterator &itr)
{
for (AdjListIterator itr1 = itr->second.begin(); itr1 != itr->second.end(); ++itr1)
{
GraphVertex *childVertex = (*itr1);
GraphVertex *parentVertex = itr->first;
if ( childVertex->getVisited() == false)
{
m_SearchOrderVector.push_back(childVertex->getVertex()); // Update the search order Vector.
childVertex->setParent(parentVertex->getVertex()); // Update the parent-link map.
childVertex->setVisited(true); // Mark the vertex as visited.
__setTypeAndInsertNewEdge(parentVertex->getVertex(),
childVertex->getVertex(),
Edge<T>::TREE_EDGE); // setup the edge type
__rundfs(m_graph.find(
__VertexInstance(childVertex->getVertex())));
}
else
{
if ( childVertex->getVertex() == parentVertex->getVertex())
{
}
}
}
}
void __insert(T inSRC, T inDST)
{
GraphIterator itr = m_graph.find(__VertexInstance(inSRC));
if ( itr != m_graph.end())
{
// Update the Adjancency list
itr->second.push_back(__VertexInstance(inDST));
}
else
{
// Create new Adjancy list
m_graph.insert(std::make_pair(__VertexInstance(inSRC),AdjList() ));
GraphIterator itr = m_graph.find(__VertexInstance(inSRC));
// Update the Adjacency List
itr->second.push_back(__VertexInstance(inDST));
}
}
// Searches if the Vertex is already allocated in the pool map
// If ye return the pointer from the map.
// Else Create new Vertex instance
// Insert into the memory pool map
// Return the pointer.
GraphVertex *__VertexInstance(T inVertex)
{
GraphVertex *newVertex = (GraphVertex *)0;
GraphInMemoryIterator itr = m_graphMemoryPool.find(inVertex);
if ( itr == m_graphMemoryPool.end())
{
newVertex = new GraphVertex(inVertex);
m_graphMemoryPool.insert(std::make_pair(inVertex,newVertex));
}
else
{
newVertex = ( GraphVertex *)itr->second;
}
return newVertex;
}
};
#endif

Answer 1

It seems you know this, but I'm reviewing for all to benefit:
There are two typical ways to implement a graph: a matrix of edges, and a sparse matrix (represented as a vector of edges for each vertex).
The matrix is an NxN structure where N is the number of vertices. Each datum is the edge length between the two vertices, so G[1][2] is the distance from 1 to 2. This also allow for directed graphs.
The other method, better for sparse graphs, is to have a vector of edges for each vertex. So you'd have vector> g where g[1] is the vector of edges for vertex 1. Each item in that vector would be and edge holding the vertex it goes to and the distance.
For more details go here: http://en.wikipedia.org/wiki/Graph_(data_structure)#Representations
Given all that, one of these implementations is likely to be quite useful to you.
EDIT1
For storing weights in a graph, on might use a structure such as vector> (as noted above). In such a case, the edge class may be like this:
class edge {
int weight;
int destination_vertex;
};
In this way, the edge from 1 to 2 would be g[1][2].