Initial commit

models/cnn.py

@@ -0,0 +1,80 @@
+import torch
+import torch.nn as nn
+import torch.optim as optim
+from torch.utils.data import DataLoader, TensorDataset
+
+
+class CNN(nn.Module):
+    def __init__(self):
+        super().__init__()
+        self.conv = nn.Sequential(
+            nn.Conv2d(1, 32, kernel_size=3),   # 28x28 -> 26x26
+            nn.ReLU(),
+            nn.MaxPool2d(2),                   # 26x26 -> 13x13
+            nn.Conv2d(32, 64, kernel_size=3),  # 13x13 -> 11x11
+            nn.ReLU(),
+            nn.MaxPool2d(2),                   # 11x11 -> 5x5
+        )
+        self.fc = nn.Sequential(
+            nn.Flatten(),
+            nn.Linear(64 * 5 * 5, 128),
+            nn.ReLU(),
+            nn.Linear(128, 10),
+        )
+
+    def forward(self, x):
+        x = x.view(-1, 1, 28, 28)
+        return self.fc(self.conv(x))
+
+
+class CNNClassifier:
+    def __init__(self, epochs=5):
+        self.epochs = epochs
+
+    def fit(self, X, y):
+        device = torch.device("cuda" if torch.cuda.is_available() else "cpu")
+        self._device = device
+
+        X_tr = torch.tensor(X, dtype=torch.float32)
+        y_tr = torch.tensor(y, dtype=torch.long)
+
+        # Hold out 10% of the training data to track progress each epoch
+        n_val = len(X_tr) // 10
+        X_val, X_tr = X_tr[:n_val], X_tr[n_val:]
+        y_val, y_tr = y_tr[:n_val], y_tr[n_val:]
+
+        loader = DataLoader(TensorDataset(X_tr, y_tr), batch_size=64, shuffle=True)
+
+        model = CNN().to(device)
+        optimizer = optim.Adam(model.parameters(), lr=1e-3)
+        loss_fn = nn.CrossEntropyLoss()
+
+        print(f"\nTraining CNN (epochs={self.epochs})")
+        for epoch in range(1, self.epochs + 1):
+            model.train()
+            total_loss = 0
+            for xb, yb in loader:
+                xb, yb = xb.to(device), yb.to(device)
+                optimizer.zero_grad()
+                loss = loss_fn(model(xb), yb)
+                loss.backward()
+                optimizer.step()
+                total_loss += loss.item()
+
+            model.eval()
+            with torch.no_grad():
+                val_pred = model(X_val.to(device)).argmax(dim=1).cpu()
+                val_accuracy = (val_pred == y_val).float().mean().item()
+
+            print(f"  epoch {epoch:2d}/{self.epochs}  loss={total_loss / len(loader):.3f}  val_accuracy={val_accuracy:.3f}")
+        print()
+
+        self._model = model
+        return self
+
+    def predict(self, X):
+        X_te = torch.tensor(X, dtype=torch.float32)
+        self._model.eval()
+        with torch.no_grad():
+            predictions = self._model(X_te.to(self._device)).argmax(dim=1).cpu().numpy()
+        return predictions