fix: fixes a bug in DBSCAN, removes println's

src/cluster/dbscan.rs

@@ -161,39 +161,60 @@ impl<T: RealNumber + Sum, D: Distance<Vec<T>, T>> DBSCAN<T, D> {
         }
 
         let mut k = 0;
-        let unassigned = -2;
+        let queued = -2;
         let outlier = -1;
+        let undefined = -3;
 
         let n = x.shape().0;
-        let mut y = vec![unassigned; n];
+        let mut y = vec![undefined; n];
 
         let algo = parameters
             .algorithm
             .fit(row_iter(x).collect(), parameters.distance)?;
 
         for (i, e) in row_iter(x).enumerate() {
-            if y[i] == unassigned {
+            if y[i] == undefined {
                 let mut neighbors = algo.find_radius(&e, parameters.eps)?;
                 if neighbors.len() < parameters.min_samples {
                     y[i] = outlier;
                 } else {
                     y[i] = k;
+
                     for j in 0..neighbors.len() {
-                        if y[neighbors[j].0] == unassigned {
-                            y[neighbors[j].0] = k;
-
-                            let mut secondary_neighbors =
-                                algo.find_radius(neighbors[j].2, parameters.eps)?;
-
-                            if secondary_neighbors.len() >= parameters.min_samples {
-                                neighbors.append(&mut secondary_neighbors);
-                            }
-                        }
-
-                        if y[neighbors[j].0] == outlier {
-                            y[neighbors[j].0] = k;
+                        if y[neighbors[j].0] == undefined {
+                            y[neighbors[j].0] = queued;
                         }
                     }
+
+                    while !neighbors.is_empty() {
+                        let neighbor = neighbors.pop().unwrap();
+                        let index = neighbor.0;
+
+                        if y[index] == outlier {
+                            y[index] = k;
+                        }
+
+                        if y[index] == undefined || y[index] == queued {
+                            y[index] = k;
+
+                            let secondary_neighbors =
+                                algo.find_radius(neighbor.2, parameters.eps)?;
+
+                            if secondary_neighbors.len() >= parameters.min_samples {
+                                for j in 0..secondary_neighbors.len() {
+                                    let label = y[secondary_neighbors[j].0];
+                                    if label == undefined {
+                                        y[secondary_neighbors[j].0] = queued;
+                                    }
+
+                                    if label == undefined || label == outlier {
+                                        neighbors.push(secondary_neighbors[j]);
+                                    }
+                                }
+                            }
+                        }
+                    }
+
                     k += 1;
                 }
             }
@@ -250,19 +271,25 @@ mod tests {
             &[1.0, 2.0],
             &[1.1, 2.1],
             &[0.9, 1.9],
-            &[1.2, 1.2],
+            &[1.2, 2.2],
             &[0.8, 1.8],
             &[2.0, 1.0],
             &[2.1, 1.1],
-            &[2.2, 1.2],
             &[1.9, 0.9],
+            &[2.2, 1.2],
             &[1.8, 0.8],
             &[3.0, 5.0],
         ]);
 
         let expected_labels = vec![0.0, 0.0, 0.0, 0.0, 0.0, 1.0, 1.0, 1.0, 1.0, 1.0, -1.0];
 
-        let dbscan = DBSCAN::fit(&x, DBSCANParameters::default().with_eps(1.0)).unwrap();
+        let dbscan = DBSCAN::fit(
+            &x,
+            DBSCANParameters::default()
+                .with_eps(0.5)
+                .with_min_samples(2),
+        )
+        .unwrap();
 
         let predicted_labels = dbscan.predict(&x).unwrap();