fix: SVS: post-review changes

src/svm/svc.rs

@@ -462,13 +462,7 @@ impl<'a, T: RealNumber, M: Matrix<T>, K: Kernel<T, M::RowVector>> Optimizer<'a,
         range
     }
 
-    fn smo(
-        &mut self,
-        idx_1: Option<usize>,
-        idx_2: Option<usize>,
-        tol: T,
-        cache: &mut Cache<T, M, K>,
-    ) -> bool {
+    fn select_pair(&mut self, idx_1: Option<usize>, idx_2: Option<usize>, cache: &mut Cache<T, M, K>) -> Option<(usize, usize, T)> {
         let mut idx_1 = idx_1;
         let mut idx_2 = idx_2;
 
@@ -532,51 +526,67 @@ impl<'a, T: RealNumber, M: Matrix<T>, K: Kernel<T, M::RowVector>> Optimizer<'a,
                     }
                 }
             }
-        }
+        }        
 
         if idx_1.is_none() || idx_2.is_none() {
-            return false;
-        }
-
-        let idx_1 = idx_1.unwrap();
-        let idx_2 = idx_2.unwrap();
-
-        if k_v_12.is_none() {
-            k_v_12 = Some(self.kernel.apply(&self.sv[idx_1].x, &self.sv[idx_2].x));
-        }
-
-        let k_v_12 = k_v_12.unwrap();
-
-        let mut curv = self.sv[idx_1].k + self.sv[idx_2].k - T::two() * k_v_12;
-        if curv <= T::zero() {
-            curv = self.tau;
-        }
-
-        let mut step = (self.sv[idx_2].grad - self.sv[idx_1].grad) / curv;
-
-        if step >= T::zero() {
-            let mut ostep = self.sv[idx_1].alpha - self.sv[idx_1].cmin;
-            if ostep < step {
-                step = ostep;
-            }
-            ostep = self.sv[idx_2].cmax - self.sv[idx_2].alpha;
-            if ostep < step {
-                step = ostep;
-            }
+            None
         } else {
-            let mut ostep = self.sv[idx_2].cmin - self.sv[idx_2].alpha;
-            if ostep > step {
-                step = ostep;
-            }
-            ostep = self.sv[idx_1].alpha - self.sv[idx_1].cmax;
-            if ostep > step {
-                step = ostep;
+
+            let idx_1 = idx_1.unwrap();
+            let idx_2 = idx_2.unwrap();
+        
+            if k_v_12.is_none() {
+                k_v_12 = Some(self.kernel.apply(&self.sv[idx_1].x, &self.sv[idx_2].x));
             }
+
+            Some((idx_1, idx_2, k_v_12.unwrap()))
         }
+    }
 
-        self.update(idx_1, idx_2, step, cache);
+    fn smo(
+        &mut self,
+        idx_1: Option<usize>,
+        idx_2: Option<usize>,
+        tol: T,
+        cache: &mut Cache<T, M, K>,
+    ) -> bool {
+        
+        match self.select_pair(idx_1, idx_2, cache) {
+            Some((idx_1, idx_2, k_v_12)) => {
+                let mut curv = self.sv[idx_1].k + self.sv[idx_2].k - T::two() * k_v_12;
+                if curv <= T::zero() {
+                    curv = self.tau;
+                }
 
-        return self.gmax - self.gmin > tol;
+                let mut step = (self.sv[idx_2].grad - self.sv[idx_1].grad) / curv;
+
+                if step >= T::zero() {
+                    let mut ostep = self.sv[idx_1].alpha - self.sv[idx_1].cmin;
+                    if ostep < step {
+                        step = ostep;
+                    }
+                    ostep = self.sv[idx_2].cmax - self.sv[idx_2].alpha;
+                    if ostep < step {
+                        step = ostep;
+                    }
+                } else {
+                    let mut ostep = self.sv[idx_2].cmin - self.sv[idx_2].alpha;
+                    if ostep > step {
+                        step = ostep;
+                    }
+                    ostep = self.sv[idx_1].alpha - self.sv[idx_1].cmax;
+                    if ostep > step {
+                        step = ostep;
+                    }
+                }
+
+                self.update(idx_1, idx_2, step, cache);
+
+                return self.gmax - self.gmin > tol;
+            },
+            None => false
+        }        
+        
     }
 
     fn update(&mut self, v1: usize, v2: usize, step: T, cache: &mut Cache<T, M, K>) {