connected components algorithm

src/gfa.rs

@@ -0,0 +1,36 @@
+#[derive(Debug)]
+pub enum Orientation {
+    Forward,
+    Reverse,
+}
+
+#[derive(Debug)]
+pub enum Entry {
+    Header {
+        version: String,
+    },
+    Segment {
+        id: String,
+        sequence: String,
+    },
+    Link {
+        from: String,
+        from_orient: Orientation,
+        to: String,
+        to_orient: Orientation,
+    },
+    Path {
+        name: String,
+        segments: Vec<(String, Orientation)>,
+    },
+    Walk {
+        sample: String,
+
+        haplotype_index: usize,
+        seq_id: String,
+        seq_start: usize,
+        seq_end: usize,
+
+        segments: Vec<(String, Orientation)>,
+    },
+}

src/graph.rs

@@ -1,26 +1,189 @@
-struct AdjacencyGraph {
-    nodes: Vec<&str>,
-    adjacencies: HashMap<&str, Vec<&str>>,
+use std::{
+    cell::RefCell,
+    collections::{HashMap, HashSet},
+    rc::Rc,
+    result,
+};
+
+#[derive(Debug)]
+pub struct AdjacencyGraph {
+    nodes: HashMap<String, String>,
+    adjacencies: HashMap<String, HashSet<String>>,
 }
 
 impl AdjacencyGraph {
-    fn new() -> Self {
+    pub fn new() -> Self {
         AdjacencyGraph {
-            nodes: Vec::new(),
+            nodes: HashMap::new(),
             adjacencies: HashMap::new(),
         }
     }
 
-    fn add_node(&mut self, node: &str) {
-        self.nodes.push(node);
-        self.adjacencies.insert(node, Vec::new());
+    pub fn add_node(&mut self, key: String, value: String) {
+        self.nodes.insert(key, value);
     }
 
-    fn add_edge(&mut self, from: &str, to: &str) {
-        self.adjacencies.get_mut(from).unwrap().push(to);
+    pub fn add_edge(&mut self, from: String, to: String) {
+        self.adjacencies
+            .entry(from)
+            .or_insert(HashSet::new())
+            .insert(to);
     }
 
-    fn neighbors(&self, node: &str) -> Option<&Vec<&str>> {
+    pub fn get_adjacencies(&self, node: &str) -> Option<&HashSet<String>> {
         self.adjacencies.get(node)
     }
+
+    pub fn adjacencies(&self) -> &HashMap<String, HashSet<String>> {
+        &self.adjacencies
+    }
+
+    pub fn opposite(&self) -> AdjacencyGraph {
+        let mut opposite = AdjacencyGraph::new();
+
+        for (from, adjacencies) in self.adjacencies.iter() {
+            for to in adjacencies {
+                opposite.add_edge(to.clone(), from.clone());
+            }
+        }
+
+        opposite
+    }
+
+    pub fn has_edge(&self, from: &str, to: &str) -> bool {
+        if let Some(adjacencies) = self.get_adjacencies(from) {
+            adjacencies.contains(&to.to_string())
+        } else {
+            false
+        }
+    }
+
+    // pub fn dfs(&self, node: String) -> HashSet<String> {
+    //     let mut visited = HashSet::new();
+    //     let mut stack = vec![node];
+
+    //     while let Some(node) = stack.pop() {
+    //         if visited.contains(&node) {
+    //             continue;
+    //         }
+
+    //         visited.insert(node.clone());
+
+    //         if let Some(adjacencies) = self.get_adjacencies(&node) {
+    //             for adj in adjacencies {
+    //                 stack.push(adj.clone());
+    //             }
+    //         }
+    //     }
+
+    //     visited
+    // }
+
+    pub fn compute_ccs(&self) -> Vec<Vec<String>> {
+        let mut visited = HashSet::new();
+        let mut result = Vec::new();
+
+        let op = self.opposite();
+
+        for node in self.nodes.keys() {
+            if visited.contains(node) {
+                continue;
+            }
+
+            let mut cc = HashSet::new();
+            let mut stack = vec![node.to_string()];
+
+            while let Some(node) = stack.pop() {
+                if cc.contains(&node) {
+                    continue;
+                }
+
+                cc.insert(node.clone());
+
+                if let Some(adjacencies) = self.get_adjacencies(&node) {
+                    for adj in adjacencies {
+                        stack.push(adj.clone());
+                    }
+                }
+
+                if let Some(adjacencies) = op.get_adjacencies(&node) {
+                    for adj in adjacencies {
+                        stack.push(adj.clone());
+                    }
+                }
+            }
+
+            visited.extend(cc.iter().map(|x| x.to_owned()));
+            result.push(cc.iter().map(|x| x.to_owned()).collect());
+        }
+
+        result
+    }
+
+    pub fn compute_ccs_2(&self) -> Vec<Vec<String>> {
+        let mut cc = HashMap::<String, Rc<RefCell<HashSet<String>>>>::new();
+
+        for node in self.nodes.keys() {
+            if cc.contains_key(node) {
+                continue;
+            }
+
+            println!("All CC: {:?}", cc);
+
+            let new_cc = Rc::new(RefCell::new(HashSet::new()));
+
+            let mut stack = vec![node.to_string()];
+
+            while let Some(node) = stack.pop() {
+                println!("New CC: {:?}", new_cc.borrow());
+
+                new_cc.borrow_mut().insert(node.clone());
+
+                if cc.contains_key(&node) {
+                    // merge the two connected components and go to the next node
+
+                    let old_cc = cc.get(&node).unwrap();
+
+                    println!("Merging {:?} with {:?}", new_cc.borrow(), old_cc.borrow());
+
+                    new_cc
+                        .borrow_mut()
+                        .extend(old_cc.borrow().iter().map(|x| x.to_owned()));
+
+                    break;
+                }
+
+                if new_cc.borrow().contains(&node) {
+                    continue;
+                }
+
+                if let Some(adjacencies) = self.get_adjacencies(&node) {
+                    for adj in adjacencies {
+                        stack.push(adj.clone());
+                    }
+                }
+            }
+
+            for n in new_cc.borrow().iter() {
+                cc.insert(n.to_owned(), new_cc.clone());
+            }
+        }
+
+        // extract the unique connected components by pointers
+        let mut result = Vec::new();
+        let mut seen = HashSet::new();
+
+        for node in self.nodes.keys() {
+            if seen.contains(node) {
+                continue;
+            }
+
+            let cc = cc.get(node).unwrap();
+            seen.extend(cc.borrow().iter().map(|x| x.to_owned()));
+
+            result.push(cc.borrow().iter().map(|x| x.to_owned()).collect());
+        }
+
+        result
+    }
 }

src/main.rs

@@ -1,5 +1,9 @@
 use argh::FromArgs;
+use gfa::{Entry, Orientation};
+use graph::AdjacencyGraph;
 
+mod gfa;
+mod graph;
 mod parser;
 
 #[derive(FromArgs, PartialEq, Debug)]
@@ -24,17 +28,58 @@ struct CommandShow {
     input: String,
 }
 
-fn main() {
+fn main() -> std::io::Result<()> {
     let opts = argh::from_env::<CliTool>();
 
     match opts.nested {
         MySubCommandEnum::Show(show) => {
-            let file = std::fs::read_to_string(show.input).expect("cannot read file");
-            let entries = parser::parse_source(file.as_str());
+            let file = std::fs::File::open(show.input)?;
+            let entries = parser::parse_source(file)?;
+
+            let mut graph = AdjacencyGraph::new();
 
             for entry in entries {
                 println!("{:?}", entry);
+
+                match entry {
+                    Entry::Segment { id, sequence } => {
+                        graph.add_node(id, sequence);
+                    }
+                    Entry::Link {
+                        from,
+                        from_orient,
+                        to,
+                        to_orient,
+                    } => match (from_orient, to_orient) {
+                        (Orientation::Forward, Orientation::Forward)
+                        | (Orientation::Reverse, Orientation::Reverse) => {
+                            graph.add_edge(from, to);
+                        }
+                        (Orientation::Forward, Orientation::Reverse)
+                        | (Orientation::Reverse, Orientation::Forward) => {
+                            graph.add_edge(to, from);
+                        }
+                    },
+                    _ => {}
                 }
             }
+
+            for (from, adjacencies) in graph.adjacencies().iter() {
+                println!(
+                    "{} -> {}",
+                    from,
+                    adjacencies
+                        .iter()
+                        .map(|to| to.to_owned())
+                        .collect::<Vec<String>>()
+                        .join(", ")
+                );
+            }
+
+            let cc = graph.compute_ccs();
+            println!("Number of connected components: {}", cc.len());
         }
+    }
+
+    Ok(())
 }

src/parser.rs

@@ -1,13 +1,11 @@
-use std::str::FromStr;
+use std::{
+    io::{self, BufRead, BufReader, Read},
+    str::FromStr,
+};
 
-#[derive(Debug)]
-pub enum Orientation {
-    Forward,
-    Reverse,
-}
+use crate::gfa::{Entry, Orientation};
 
-impl From<&str> for Orientation {
-    fn from(s: &str) -> Self {
+fn parse_orientation(s: &str) -> Orientation {
     match s {
         "+" => Orientation::Forward,
         ">" => Orientation::Forward,
@@ -15,38 +13,6 @@ impl From<&str> for Orientation {
         "<" => Orientation::Reverse,
         _ => panic!("Invalid orientation: {}", s),
     }
-    }
-}
-
-#[derive(Debug)]
-pub enum Entry {
-    Header {
-        version: String,
-    },
-    Segment {
-        id: String,
-        sequence: String,
-    },
-    Link {
-        from: String,
-        from_orient: Orientation,
-        to: String,
-        to_orient: Orientation,
-    },
-    Path {
-        name: String,
-        segments: Vec<(String, Orientation)>,
-    },
-    Walk {
-        sample: String,
-
-        haplotype_index: usize,
-        seq_id: String,
-        seq_start: usize,
-        seq_end: usize,
-
-        segments: Vec<(String, Orientation)>,
-    },
 }
 
 /// Parse a line of the source file into a Header struct
@@ -87,9 +53,9 @@ fn parse_link(line: &str) -> Entry {
 
     Entry::Link {
         from: columns[1].to_string(),
-        from_orient: columns[2].into(),
+        from_orient: parse_orientation(columns[2]),
         to: columns[3].to_string(),
-        to_orient: columns[4].into(),
+        to_orient: parse_orientation(columns[4]),
     }
 }
 
@@ -107,7 +73,7 @@ fn parse_path(line: &str) -> Entry {
             .split(',')
             .map(|s| {
                 let (name, orient) = s.split_at(s.len() - 1);
-                (name.to_string(), orient.into())
+                (name.to_string(), parse_orientation(orient))
             })
             .collect(),
     }
@@ -126,7 +92,7 @@ fn parse_path_segments(s: &str) -> Vec<(String, Orientation)> {
         let (name, r) = r.split_at(r.find(['<', '>']).unwrap_or(r.len()));
 
         rest = r;
-        result.push((name.to_string(), orient.into()));
+        result.push((name.to_string(), parse_orientation(orient)));
 
         if rest.is_empty() {
             break;
@@ -156,10 +122,12 @@ fn parse_walk(line: &str) -> Entry {
     }
 }
 
-pub fn parse_source(source: &str) -> Vec<Entry> {
+pub fn parse_source<R: Read>(reader: R) -> io::Result<Vec<Entry>> {
     let mut entries = Vec::new();
-    for line in source.lines() {
+    for line in BufReader::new(reader).lines() {
+        let line = line?;
         let line = line.trim();
+
         if line.is_empty() || line.starts_with('#') {
             continue;
         }
@@ -180,5 +148,6 @@ pub fn parse_source(source: &str) -> Vec<Entry> {
         };
         entries.push(entry);
     }
-    entries
+
+    Ok(entries)
 }