Graph * get_full_graph(int count)
{
ARGEdit ed; // The object used to create the graph
// Insert the three nodes
for(int i=0; i<count; i++)
ed.InsertNode(NULL); // The inserted node will have index i.
// NULL stands for no semantic attribute.
// Insert the edges
for(int i=0; i<count; i++)
for(int j=0; j<count; j++)
if (i!=j)
ed.InsertEdge(i, j, NULL); // NULL stands for no sem. attribute.
return new Graph(&ed);
}
Graph* readGraphBinary(const char* filename) {
ARGEdit ed;
ifstream in (filename, ios::in|ios::binary);
int n = r(in); // number of vertices
for(int i = 0; i < n; i++)
ed.InsertNode(NULL);
for (int i = 0; i < n; i++) {
int cnt = r(in);
for (int j = 0; j < cnt; j++) {
int k = r(in);
ed.InsertEdge(i, k, NULL);
}
}
in.close();
return new Graph(&ed);
}
/*----------------------------------------------------------------
* Extract a random subgraph from a graph 'g' with a given
* number of nodes ('nodes'). If 'connected' is true, the
* subgraph will be connected. Attributes of the subgraph are
* shared with the original graph.
* The subgraph will not inherit the node/edge destroy functions
* nor the node/edge compatibility predicates.
*
* IMPORTANT
* You have to init the random seed by calling srand() before
* invoking this function.
----------------------------------------------------------------*/
Graph* ExtractSubgraph(Graph *g, int nodes, bool connected)
{ assert(g!=NULL);
assert(nodes>=0);
assert(nodes<=g->NodeCount());
int i,j;
int n=g->NodeCount();
node_id *map=(node_id*)calloc(n, sizeof(node_id));
if (n>0 && map==NULL)
OUT_OF_MEMORY();
for(i=0; i<n; i++)
map[i]=NULL_NODE;
ARGEdit ed;
visit_param param;
for(i=0; i<nodes; i++)
{ // Choose a node which has not yet been used
node_id id=irand(0, n-1);
node_id id0=id;
bool found=false;
do {
while (map[id]!=NULL_NODE)
{ if (++id == n)
id=0;
if (id==id0)
{ if (i==0 || !connected)
CANT_HAPPEN();
else
FAIL("Cannot extract a connected subgraph");
}
}
// check for the connectedness of the new node
if (i>0 && connected)
{
for(j=0; j<g->OutEdgeCount(id) && !found; j++)
{ if (map[g->GetOutEdge(id, j)]!=NULL_NODE)
found=true;
}
for(j=0; j<g->InEdgeCount(id) && !found; j++)
{ if (map[g->GetInEdge(id, j)]!=NULL_NODE)
found=true;
}
if (!found)
{ if (++id == n)
id=0;
if (id==id0)
FAIL("Cannot extract a connected subgraph");
}
}
else
{ found=true;
}
} while (!found);
// now add the node to the ARGEdit
map[id]=i;
ed.InsertNode(g->GetNodeAttr(id));
}
// Now add the edges to the new graph
param.ed=&ed;
param.map=map;
for(i=0; i<n; i++)
{ if (map[i]!=NULL_NODE)
g->VisitOutEdges(i, edge_insert_visitor, ¶m);
}
// Construct the graph and return it
Graph *sub=new Graph(&ed);
return sub;
}
