Update modeling_core.py

modeling_core.py

@@ -1,3 +1,4 @@
+#!/usr/bin/env python3
 """
 GeoLIP Core — Back to Basics
 ==============================
@@ -222,25 +223,110 @@ class GeoLIPCore(nn.Module):
             ld['nce'] = l_nce
             ld['nce_acc'] = nce_acc
 
+        # ── Anchor attraction: pull each embedding toward its nearest anchor ──
+        anchors_n = F.normalize(self.constellation.anchors, dim=-1)
+        cos_to_anchors = emb @ anchors_n.T          # (B, n_anchors)
+        nearest_cos = cos_to_anchors.max(dim=1).values  # (B,)
+        l_attract = (1.0 - nearest_cos).mean()       # 0 when on top of anchor
+        ld['attract'] = l_attract
+        ld['nearest_cos'] = nearest_cos.mean().item()
+
         # CV
         l_cv = self._cv_loss(emb)
         ld['cv'] = l_cv
 
         # Anchor spread
-        an = F.normalize(self.constellation.anchors, dim=-1)
-        sim_a = an @ an.T
-        mask = ~torch.eye(an.shape[0], dtype=torch.bool, device=an.device)
+        sim_a = anchors_n @ anchors_n.T
+        mask = ~torch.eye(anchors_n.shape[0], dtype=torch.bool, device=anchors_n.device)
         l_spread = F.relu(sim_a[mask]).mean()
         ld['spread'] = l_spread
 
         # Total
         loss = (l_ce
                 + ld.get('nce', 0.0) * 1.0
+                + l_attract * 0.5
                 + l_cv * 0.01
                 + l_spread * 0.001)
         ld['total'] = loss
         return loss, ld
 
+    @torch.no_grad()
+    def push_anchors_to_centroids(self, emb_buffer, label_buffer, lr=0.1):
+        """
+        Push anchors toward CLASS centroids, not nearest-anchor centroids.
+
+        Phase 1: Compute class centroids from labels
+        Phase 2: Each class owns (n_anchors / n_classes) anchors
+        Phase 3: Assigned anchors blend toward their class centroid
+                 with small angular offsets so they don't all collapse
+
+        This works even when anchors start bunched at origin.
+        """
+        anchors = self.constellation.anchors.data  # (A, D)
+        n_a = anchors.shape[0]
+        emb_n = F.normalize(emb_buffer, dim=-1)
+        device = anchors.device
+
+        # Phase 1: class centroids
+        classes = label_buffer.unique()
+        n_cls = classes.shape[0]
+        centroids = []
+        for c in classes:
+            mask = label_buffer == c
+            if mask.sum() > 0:
+                centroids.append(F.normalize(emb_n[mask].mean(0, keepdim=True), dim=-1))
+        if len(centroids) == 0:
+            return 0
+        centroids = torch.cat(centroids, dim=0)  # (C, D)
+
+        # Phase 2: assign anchors to classes round-robin
+        # Sort anchors by cosine to each centroid, greedily assign
+        anchors_n = F.normalize(anchors, dim=-1)
+        cos = anchors_n @ centroids.T  # (A, C)
+        anchors_per_class = n_a // n_cls
+        assigned_class = torch.full((n_a,), -1, dtype=torch.long, device=device)
+        class_count = torch.zeros(n_cls, dtype=torch.long, device=device)
+
+        # Greedy: for each anchor, assign to its best class if that class has room
+        _, flat_idx = cos.flatten().sort(descending=True)
+        for idx in flat_idx:
+            a = (idx // n_cls).item()
+            c = (idx % n_cls).item()
+            if assigned_class[a] >= 0:
+                continue
+            if class_count[c] >= anchors_per_class + 1:  # +1 for remainder
+                continue
+            assigned_class[a] = c
+            class_count[c] += 1
+            if (assigned_class >= 0).all():
+                break
+
+        # Unassigned leftovers → nearest centroid
+        unassigned = (assigned_class < 0).nonzero(as_tuple=True)[0]
+        if len(unassigned) > 0:
+            leftover_cos = anchors_n[unassigned] @ centroids.T
+            assigned_class[unassigned] = leftover_cos.argmax(dim=1)
+
+        # Phase 3: push each anchor toward its class centroid
+        moved = 0
+        for a in range(n_a):
+            c = assigned_class[a].item()
+            target = centroids[c]
+            # Add small angular offset so co-class anchors don't collapse
+            rank_in_class = (assigned_class[:a] == c).sum().item()
+            if anchors_per_class > 1 and rank_in_class > 0:
+                # Tiny perpendicular perturbation
+                noise = torch.randn_like(target) * 0.05
+                noise = noise - (noise * target).sum() * target  # project out radial
+                target = F.normalize((target + noise).unsqueeze(0), dim=-1).squeeze(0)
+
+            anchors[a] = F.normalize(
+                (anchors_n[a] + lr * (target - anchors_n[a])).unsqueeze(0),
+                dim=-1).squeeze(0)
+            moved += 1
+
+        return moved
+
     def _cv_loss(self, emb, n_samples=64, n_points=5):
         B = emb.shape[0]
         if B < n_points: return torch.tensor(0.0, device=emb.device)
@@ -265,4 +351,3 @@ class GeoLIPCore(nn.Module):
         vt = torch.stack(vols)
         cv = vt.std() / (vt.mean() + 1e-8)
         return (cv - self.cv_target).pow(2)
-