uint8_t _update_avg_graph(
graph_t *gin,
graph_t *gavg,
array_t *nodemap,
edge_weight_t edgeweight,
uint16_t ninputs) {
uint64_t i;
uint64_t j;
uint32_t ginnodes;
uint32_t *nbrs;
uint32_t nnbrs;
uint32_t outi;
uint32_t outj;
float inwt;
float outwt;
ginnodes = graph_num_nodes(gin);
for (i = 0; i < ginnodes; i++) {
outi = *(uint32_t *)array_getd(nodemap, i);
nnbrs = graph_num_neighbours(gin, i);
nbrs = graph_get_neighbours(gin, i);
for (j = 0; j < nnbrs; j++) {
if (i >= nbrs[j]) continue;
outj = *(uint32_t *)array_getd(nodemap, nbrs[j]);
/*will have no effect if edge already exists*/
graph_add_edge(gavg, outi, outj, 0.0);
inwt = graph_get_weight(gin, i, nbrs[j]);
outwt = graph_get_weight(gavg, outi, outj);
switch (edgeweight) {
case SUM_WEIGHTS: outwt = outwt + inwt; break;
case COUNT_EDGES: outwt = outwt + 1; break;
case AVG_WEIGHTS: outwt = outwt + (inwt/ninputs); break;
default: goto fail;
}
if (graph_set_weight(gavg, outi, outj, outwt))
goto fail;
}
}
return 0;
fail:
return 1;
}
static int path_decimate(gstack_t** path, double* Dmin)
{
size_t n = gstack_size(*path);
double xmin = pow(*Dmin, 2);
corner_t cns[n];
/*
empty the stack into a corners array - we do this
in reverse order so the gstack_push below gives us
a gstack_t in the same order (needed due to an
assumed orientation of the boundaries)
*/
for (int i = 0 ; i < n ; i++)
{
if (gstack_pop(*path, (void*)(cns+(n-1-i))) != 0)
return -1;
}
/* cache metric tensor and ellipse centres */
vector_t e[n];
m2_t mt[n];
for (int i = 0 ; i < n ; i++)
{
ellipse_t E;
arrow_ellipse(&(cns[i].A), &E);
mt[i] = ellipse_mt(E);
e[i] = E.centre;
}
/* create ellipse intersection graph */
graph_t G;
if (graph_init(n,&G) != 0)
return -1;
size_t err = 0;
for (int i = 0 ; i < n-1 ; i++)
{
for (int j = i+1 ; j < n ; j++)
{
double x = contact_mt(vsub(e[j], e[i]), mt[i], mt[j]);
/*
failed contact() results in edge not being
included in the graph so possible intesection
survives - save the number for a warning (below)
*/
if (x<0)
{
err++;
continue;
}
/*
weight of each node is the maximum of the
contact-distances of the incoming edges
*/
if (x < xmin)
{
double
w1 = graph_get_weight(G, i),
w2 = graph_get_weight(G, j);
graph_set_weight(G, i, MAX(w1, x));
graph_set_weight(G, j, MAX(w2, x));
if (graph_add_edge(G, i, j) != 0)
return -1;
}
}
}
if (err)
fprintf(stderr,"failed contact distance for %i pairs\n", (int)err);
/* greedy node deletion to obtain non-intersecting subset */
size_t maxi;
while (graph_maxedge(G, &maxi) > 0)
if (graph_del_node(G, maxi) != 0)
return -1;
/* dump back into gstack */
for (int i = 0 ; i < n ; i++)
if ( !graph_node_flag(G, i, NODE_STALE) )
gstack_push(*path, (void*)(cns+i));
graph_clean(&G);
return 1;
}