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fixed concave hull ordering

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randogoth 2024-04-01 10:13:07 +03:00
parent 6c215809fb
commit 7e8b5f217e
1 changed files with 48 additions and 37 deletions
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85
src/lib.rs
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@ -467,51 +467,62 @@ impl Xenobalanus {
} }
// Order the hull edge indices to form a continuous path // Order the hull edge indices to form a continuous path
let ordered_indices = self.order_hull_edges(hull_edge_indices)?; let ordered_indices = self.ordered_vertices(hull_edge_indices)?;
Ok(ordered_indices) Ok(ordered_indices)
} }
/// Attempts to order hull edges into a continuous path. /// Attempts to order hull edges into a continuous path.
pub fn order_hull_edges(&self, hull_edge_indices: Vec<(usize, usize)>) -> Result<Vec<usize>, &'static str> { fn ordered_vertices(&self, edges: Vec<(usize, usize)>) -> Result<Vec<usize>, &'static str> {
if hull_edge_indices.is_empty() { let mut graph = HashMap::new();
return Err("No edges provided."); // Create the graph and track degrees
for (a, b) in &edges {
graph.entry(*a).or_insert_with(HashSet::new).insert(*b);
graph.entry(*b).or_insert_with(HashSet::new).insert(*a);
} }
let mut visited: HashSet<usize> = HashSet::new(); // Verify the graph's conditions for an Eulerian path
let mut ordered_point_indices: Vec<usize> = Vec::new(); let mut odd_degree_vertices = vec![];
for (&vertex, neighbors) in &graph {
// Initialize with the first edge's indices if neighbors.len() % 2 != 0 {
let (start_idx, mut current_idx) = hull_edge_indices[0]; odd_degree_vertices.push(vertex);
ordered_point_indices.push(start_idx); }
visited.insert(start_idx); }
if odd_degree_vertices.len() > 2 {
while visited.len() < hull_edge_indices.len() + 1 { return Err("Graph cannot have more than two vertices of odd degree");
let mut found_next = false; }
for &(p1_idx, p2_idx) in &hull_edge_indices { // Choose a start vertex
if p1_idx == current_idx && !visited.contains(&p2_idx) { let start = if !odd_degree_vertices.is_empty() {
ordered_point_indices.push(p2_idx); odd_degree_vertices[0]
visited.insert(p2_idx); } else {
current_idx = p2_idx; *graph.keys().next().ok_or("Graph is empty")?
found_next = true; };
break;
} else if p2_idx == current_idx && !visited.contains(&p1_idx) { let mut stack = vec![start];
ordered_point_indices.push(p1_idx); let mut path = Vec::new(); // This will store the path of vertices
visited.insert(p1_idx); let mut visited_edges = HashSet::new(); // To track visited edges
current_idx = p1_idx;
found_next = true; while let Some(node) = stack.pop() {
break; path.push(node); // Add vertex to the path
if let Some(neighbors) = graph.get_mut(&node) {
for &next in neighbors.clone().iter() {
// Ensure each edge is traversed exactly once
if !visited_edges.contains(&(node, next)) && !visited_edges.contains(&(next, node)) {
visited_edges.insert((node, next));
visited_edges.insert((next, node)); // Mark edge as visited in both directions
stack.push(next); // Visit next vertex
break; // Break after pushing one neighbor to ensure we follow one continuous path
}
} }
} }
if !found_next {
return Err("Failed to order all concave hull vertices into a continuous path.");
}
} }
// Convert indices to Points // Check if all edges were visited
Ok(hull_edge_indices.iter().map(|&(start_idx, _)| start_idx).collect()) if visited_edges.len() / 2 != edges.len() {
return Err("Graph is not Eulerian: no path uses all edges exactly once");
}
Ok(path)
} }
} }