void SaveAsciiGraph(graphP theGraph, char *filename) { int e, EsizeOccupied, vertexLabelFix; FILE *outfile = fopen(filename, "wt"); fprintf(outfile, "%s\n", filename); // This edge list file format uses 1-based vertex numbering, and the current code // internally uses 1-based indexing by default, so this vertex label 'fix' adds zero // But earlier code used 0-based indexing and added one on output, so we replicate // that behavior in case the current code has been compiled with zero-based indexing. vertexLabelFix = 1 - gp_GetFirstVertex(theGraph); // Iterate over the edges of the graph EsizeOccupied = gp_EdgeInUseIndexBound(theGraph); for (e = gp_GetFirstEdge(theGraph); e < EsizeOccupied; e+=2) { // Only output edges that haven't been deleted (i.e. skip the edge holes) if (gp_EdgeInUse(theGraph, e)) { fprintf(outfile, "%d %d\n", gp_GetNeighbor(theGraph, e) + vertexLabelFix, gp_GetNeighbor(theGraph, e+1) + vertexLabelFix); } } // Since vertex numbers are at least 1, this indicates the end of the edge list fprintf(outfile, "0 0\n"); fclose(outfile); }
int _CheckEmbeddingFacialIntegrity(graphP theGraph) { stackP theStack = theGraph->theStack; int EsizeOccupied, v, e, eTwin, eStart, eNext, NumFaces, connectedComponents; if (theGraph == NULL) return NOTOK; /* The stack need only contain 2M entries, one for each edge record. With max M at 3N, this amounts to 6N integers of space. The embedding structure already contains this stack, so we just make sure it starts out empty. */ sp_ClearStack(theStack); /* Push all arcs and set them to unvisited */ EsizeOccupied = gp_EdgeInUseIndexBound(theGraph); for (e = gp_GetFirstEdge(theGraph); e < EsizeOccupied; e+=2) { // Except skip edge holes if (gp_EdgeInUse(theGraph, e)) { sp_Push(theStack, e); gp_ClearEdgeVisited(theGraph, e); eTwin = gp_GetTwinArc(theGraph, e); sp_Push(theStack, eTwin); gp_ClearEdgeVisited(theGraph, eTwin); } } // There are M edges, so we better have pushed 2M arcs just now // i.e. testing that the continue above skipped only edge holes if (sp_GetCurrentSize(theStack) != 2*theGraph->M) return NOTOK; /* Read faces until every arc is used */ NumFaces = 0; while (sp_NonEmpty(theStack)) { /* Get an arc; if it has already been used by a face, then don't use it to traverse a new face */ sp_Pop(theStack, eStart); if (gp_GetEdgeVisited(theGraph, eStart)) continue; e = eStart; do { eNext = gp_GetNextArcCircular(theGraph, gp_GetTwinArc(theGraph, e)); if (gp_GetEdgeVisited(theGraph, eNext)) return NOTOK; gp_SetEdgeVisited(theGraph, eNext); e = eNext; } while (e != eStart); NumFaces++; } /* Count the external face once rather than once per connected component; each connected component is detected by the fact that it has no DFS parent, except in the case of isolated vertices, no face was counted so we do not subtract one. */ connectedComponents = 0; for (v = gp_GetFirstVertex(theGraph); gp_VertexInRange(theGraph, v); v++) { if (gp_IsDFSTreeRoot(theGraph, v)) { if (gp_GetVertexDegree(theGraph, v) > 0) NumFaces--; connectedComponents++; } } NumFaces++; /* Test number of faces using the extended Euler's formula. For connected components, Euler's formula is f=m-n+2, but for disconnected graphs it is extended to f=m-n+1+c where c is the number of connected components.*/ return NumFaces == theGraph->M - theGraph->N + 1 + connectedComponents ? OK : NOTOK; }