working cycle detection and edge classification

src/adv_graph.rs

@@ -0,0 +1,16 @@
+use std::{collections::HashMap, hash::Hash};
+
+struct GraphEdge {
+    from: u32,
+    to: u32,
+}
+
+pub struct Graph<V, E>
+where
+    V: Hash + Eq + Clone,
+{
+    nodes: HashMap<V, u32>,
+    edges: HashMap<(u32, u32), E>,
+
+    adjacency_list: HashMap<u32, Vec<(u32, u32)>>,
+}

src/graph.rs

@@ -1,12 +1,20 @@
 use std::{
     cell::RefCell,
-    collections::{HashMap, HashSet, VecDeque},
+    collections::{BTreeMap, HashMap, HashSet, VecDeque},
     fmt::Debug,
     hash::Hash,
     rc::Rc,
 };
 
-use indicatif::ProgressIterator;
+use indicatif::{ProgressBar, ProgressIterator};
+
+#[derive(Debug, Hash, PartialEq, Eq, PartialOrd, Ord)]
+pub enum EdgeType {
+    TreeEdge,
+    BackEdge,
+    ForwardEdge,
+    CrossEdge,
+}
 
 #[derive(Debug)]
 pub struct AdjacencyGraph<V>
@@ -109,10 +117,171 @@ where
 
                 return Some(node.clone());
             }
+
             None
         })
     }
 
+    /// This computes if this undirected graph is cyclic or not by searching for an oriented cycle in the graph
+    pub fn is_cyclic(&self) -> bool {
+        let mut remaining_nodes = self.nodes.iter().collect::<HashSet<_>>();
+
+        // let progress_bar = ProgressBar::new(self.nodes.len() as u64);
+        // let mut visited_count = 0;
+
+        while !remaining_nodes.is_empty() {
+            let start: &V = remaining_nodes.iter().next().unwrap();
+
+            // visited_count += 1;
+            remaining_nodes.remove(start);
+            // progress_bar.inc(1);
+
+            let mut dfs_visited = HashSet::new();
+            let mut stack = VecDeque::new();
+            stack.push_back(start);
+
+            // start a new dfs from the current node
+            while let Some(node) = stack.pop_back() {
+                if dfs_visited.contains(node) {
+                    // println!("Found cycle after {} nodes", visited_count);
+                    // progress_bar.finish();
+                    return true;
+                }
+
+                // visited_count += 1;
+                remaining_nodes.remove(node);
+                // progress_bar.inc(1);
+
+                dfs_visited.insert(node.clone());
+
+                if let Some(adjacencies) = self.get_adjacencies(node) {
+                    stack.extend(adjacencies);
+                }
+            }
+        }
+
+        // println!("Found cycle after {} nodes", visited_count);
+        // progress_bar.finish();
+        false
+    }
+
+    pub fn compute_edge_types(&self) -> HashMap<(&V, &V), EdgeType> {
+        /// To correctly compute the start and end times of the nodes in the graph, we need to keep do work before and after the recursion
+        /// call
+        enum RecurseState {
+            Before,
+            AfterNeighbor,
+        }
+
+        let mut edge_types = HashMap::new();
+
+        let mut visited = HashSet::new();
+        let mut start_times = HashMap::new();
+        let mut end_times = HashMap::new();
+
+        let mut time = 0;
+
+        let progress_bar = ProgressBar::new(self.nodes.len() as u64);
+
+        for node in self.nodes.iter() {
+            if visited.contains(node) {
+                continue;
+            }
+
+            let mut stack = Vec::new();
+
+            stack.push((node, RecurseState::Before));
+
+            while let Some((node, state)) = stack.pop() {
+                match state {
+                    RecurseState::Before => {
+                        progress_bar.inc(1);
+                        visited.insert(node.clone());
+                        start_times.insert(node, time);
+                        time += 1;
+
+                        // this is extremely important that is before the adjacencies to correctly
+                        // iterate over the graph
+
+                        if let Some(adjacencies) = self.get_adjacencies(node) {
+                            for adj in adjacencies {
+                                // if visited.contains(adj) {
+                                //     if start_times.get(adj) < start_times.get(node) {
+                                //         edge_types.insert((node, adj), EdgeType::BackEdge);
+                                //     } else {
+                                //         edge_types.insert((node, adj), EdgeType::CrossEdge);
+                                //     }
+                                // } else {
+                                //     edge_types.insert((node, adj), EdgeType::ForwardEdge);
+                                //     stack.push((adj, RecurseState::Before));
+                                // }
+
+                                stack.push((node, RecurseState::AfterNeighbor));
+
+                                if !visited.contains(adj) {
+                                    edge_types.insert((node, adj), EdgeType::TreeEdge);
+                                    stack.push((adj, RecurseState::Before));
+                                } else {
+                                    let start_time_node = start_times.get(node).unwrap();
+                                    let start_time_adj = start_times.get(adj).unwrap();
+                                    let end_time_node = end_times.get(node).unwrap_or(&0);
+                                    let end_time_adj = end_times.get(adj).unwrap_or(&0);
+
+                                    if start_time_node < start_time_adj
+                                        && end_time_node > end_time_adj
+                                    {
+                                        edge_types.insert((node, adj), EdgeType::ForwardEdge);
+                                    } else if start_time_node > start_time_adj
+                                        && end_time_node < end_time_adj
+                                    {
+                                        edge_types.insert((node, adj), EdgeType::BackEdge);
+                                    // } else if start_time_node > start_time_adj
+                                    //     && end_time_node > end_time_adj
+                                    // {
+                                    //     edge_types.insert((node, adj), EdgeType::CrossEdge);
+                                    } else {
+                                        edge_types.insert((node, adj), EdgeType::CrossEdge);
+                                    }
+                                }
+                            }
+                        }
+                    }
+                    RecurseState::AfterNeighbor => {
+                        end_times.insert(node, time);
+                        time += 1;
+                    }
+                }
+            }
+        }
+
+        // for node in self.nodes.iter() {
+        //     let mut stack = Vec::new();
+
+        //     if visited.contains(node) {
+        //         continue;
+        //     }
+
+        //     stack.push(node);
+
+        //     while let Some(node) = stack.pop() {
+        //         visited.insert(node.clone());
+
+        //         if let Some(adjacencies) = self.get_adjacencies(node) {
+        //             for adj in adjacencies {
+        //                 if visited.contains(adj) {
+        //                     // ...
+        //                 } else {
+        //                     edge_types.insert((node, adj), EdgeType::TreeEdge);
+        //                     stack.push(adj);
+        //                 }
+        //             }
+        //         }
+        //     }
+        // }
+
+        edge_types
+    }
+
     pub fn shortest_path_matrix(&self) -> HashMap<&V, HashMap<&V, usize>> {
         let mut result = HashMap::new();
 
@@ -270,4 +439,45 @@ where
 
         result
     }
+
+    /// This function prints the number of nodes, edges and a histogram of the degrees of the nodes
+    /// in the graph (computing the degrees might take a long time)
+    pub fn print_stats(&self) {
+        let mut vertices_degrees = HashMap::new();
+
+        for (from, tos) in self
+            .adjacencies
+            .iter()
+            .progress()
+            .with_style(
+                indicatif::ProgressStyle::default_bar()
+                    .template("{prefix} {spinner} [{elapsed_precise}] [{wide_bar}] {pos}/{len}")
+                    .unwrap(),
+            )
+            .with_prefix("computing nodes degrees")
+        {
+            *vertices_degrees.entry(from).or_insert(0) += tos.len();
+
+            for to in tos {
+                *vertices_degrees.entry(to).or_insert(0) += 1;
+            }
+        }
+
+        let histogram: BTreeMap<usize, usize> = vertices_degrees
+            .iter()
+            .map(|(_, degree)| *degree)
+            .fold(BTreeMap::new(), |mut acc, degree| {
+                *acc.entry(degree).or_insert(0) += 1;
+                acc
+            });
+
+        println!("Stats:");
+        println!("Nodes: {}", self.nodes.len());
+        println!("Edges: {}", self.edges().count());
+
+        println!("Histogram:");
+        for (degree, count) in histogram.iter() {
+            println!("{}: {}", degree, count);
+        }
+    }
 }

src/lib.rs

@@ -1,4 +1,7 @@
+pub mod adv_graph;
 pub mod gfa;
 pub mod graph;
 pub mod graph_2;
 pub mod parser;
+
+mod utils;

src/main.rs

@@ -1,5 +1,5 @@
 use std::{
-    collections::HashMap,
+    collections::{BTreeMap, HashMap},
     io::{BufRead, BufReader},
 };
 
@@ -16,12 +16,12 @@ mod parser;
 /// Strumento CLI per il progetto di Algoritmi e Strutture Dati 2024
 struct CliTool {
     #[argh(subcommand)]
-    nested: MySubCommandEnum,
+    nested: CliSubcommands,
 }
 
 #[derive(FromArgs, PartialEq, Debug)]
 #[argh(subcommand)]
-enum MySubCommandEnum {
+enum CliSubcommands {
     Show(CommandShow),
 }
 
@@ -38,10 +38,12 @@ fn main() -> std::io::Result<()> {
     let opts = argh::from_env::<CliTool>();
 
     match opts.nested {
-        MySubCommandEnum::Show(show) => {
+        CliSubcommands::Show(show) => {
             let file_lines_count = BufReader::new(std::fs::File::open(&show.input)?)
                 .lines()
-                .progress_with(indicatif::ProgressBar::new_spinner().with_message("counting lines"))
+                .progress_with(
+                    indicatif::ProgressBar::new_spinner().with_message("estimating line count"),
+                )
                 .count() as u64;
 
             let file = std::fs::File::open(show.input)?;
@@ -84,10 +86,28 @@ fn main() -> std::io::Result<()> {
             //     );
             // }
 
-            let cc = graph.compute_ccs();
+            // let cc = graph.compute_ccs();
 
             // println!("CCs: {:?}", cc);
-            println!("Number of connected components: {}", cc.len());
+            // println!("Number of connected components: {}", cc.len());
+
+            // graph.print_stats();
+
+            println!("Graph has cycles: {}", graph.is_cyclic());
+
+            let edge_types = graph.compute_edge_types();
+
+            let edge_type_histogram: BTreeMap<_, _> = edge_types
+                .iter()
+                .map(|(_, edge_type)| edge_type)
+                .fold(BTreeMap::new(), |mut acc, edge_type| {
+                    *acc.entry(edge_type).or_insert(0) += 1;
+                    acc
+                });
+
+            println!("Edge types histogram: {:?}", edge_type_histogram);
+
+            println!("Cleaning up...");
         }
     }
 

src/parser.rs

@@ -174,8 +174,24 @@ pub fn parse_source<R: Read>(reader: R, line_count: u64) -> io::Result<Vec<Entry
         entries.push(entry);
     }
 
-    for s in skipped {
+    for (s, count) in skipped.iter().fold(Vec::new(), |mut acc, s| {
-        eprintln!("skipped line type: {}", s);
+        if let Some((last, count)) = acc.last_mut() {
+            if *last == s {
+                *count += 1;
+            } else {
+                acc.push((s, 1));
+            }
+        } else {
+            acc.push((s, 1));
+        }
+
+        acc
+    }) {
+        if count > 1 {
+            eprintln!("skipped {} lines of type: {}", count, s);
+        } else {
+            eprintln!("skipped line type: {}", s);
+        }
     }
 
     Ok(entries)

src/utils.rs

@@ -0,0 +1 @@
+