Add siamese glvq

README.md

@@ -43,17 +43,18 @@ To assist in the development process, you may also find it useful to install
 
 ## Available models
 
-- [X] GLVQ
+- GLVQ
-- [X] Neural Gas
+- Siamese GLVQ
+- Neural Gas
 
 ## Work in Progress
-- [ ] CBC
+- CBC
 
 ## Planned models
-- [ ] GMLVQ
+- GMLVQ
-- [ ] Local-Matrix GMLVQ
+- Local-Matrix GMLVQ
-- [ ] Limited-Rank GMLVQ
+- Limited-Rank GMLVQ
-- [ ] GTLVQ
+- GTLVQ
-- [ ] RSLVQ
+- RSLVQ
-- [ ] PLVQ
+- PLVQ
-- [ ] LVQMLN
+- LVQMLN

examples/siamese_glvq_iris.py

@@ -0,0 +1,113 @@
+"""Siamese GLVQ example using all four dimensions of the Iris dataset."""
+
+import numpy as np
+import pytorch_lightning as pl
+import torch
+from matplotlib import pyplot as plt
+from prototorch.datasets.abstract import NumpyDataset
+from prototorch.models.glvq import SiameseGLVQ
+from sklearn.datasets import load_iris
+from torch.utils.data import DataLoader
+from torch.utils.tensorboard import SummaryWriter
+
+
+class VisualizationCallback(pl.Callback):
+    def __init__(self,
+                 x_train,
+                 y_train,
+                 title="Prototype Visualization",
+                 cmap="viridis"):
+        super().__init__()
+        self.x_train = x_train
+        self.y_train = y_train
+        self.title = title
+        self.fig = plt.figure(self.title)
+        self.cmap = cmap
+
+    def on_epoch_end(self, trainer, pl_module):
+        protos = pl_module.prototypes
+        plabels = pl_module.prototype_labels
+        x_train, y_train = self.x_train, self.y_train
+        x_train = pl_module.backbone(torch.Tensor(x_train)).detach()
+        protos = pl_module.backbone(torch.Tensor(protos)).detach()
+        ax = self.fig.gca()
+        ax.cla()
+        ax.set_title(self.title)
+        ax.axis("off")
+        ax.scatter(x_train[:, 0], x_train[:, 1], c=y_train, edgecolor="k")
+        ax.scatter(
+            protos[:, 0],
+            protos[:, 1],
+            c=plabels,
+            cmap=self.cmap,
+            edgecolor="k",
+            marker="D",
+            s=50,
+        )
+        x = np.vstack((x_train, protos))
+        x_min, x_max = x[:, 0].min() - 0.2, x[:, 0].max() + 0.2
+        y_min, y_max = x[:, 1].min() - 0.2, x[:, 1].max() + 0.2
+        xx, yy = np.meshgrid(np.arange(x_min, x_max, 1 / 50),
+                             np.arange(y_min, y_max, 1 / 50))
+        mesh_input = np.c_[xx.ravel(), yy.ravel()]
+        y_pred = pl_module.predict_latent(torch.Tensor(mesh_input))
+        y_pred = y_pred.reshape(xx.shape)
+
+        ax.contourf(xx, yy, y_pred, cmap=self.cmap, alpha=0.35)
+        ax.set_xlim(left=x_min + 0, right=x_max - 0)
+        ax.set_ylim(bottom=y_min + 0, top=y_max - 0)
+        tb = pl_module.logger.experiment
+        tb.add_figure(tag=f"{self.title}",
+                      figure=self.fig,
+                      global_step=trainer.current_epoch,
+                      close=False)
+        plt.pause(0.1)
+
+
+class Backbone(torch.nn.Module):
+    def __init__(self, input_size=4, hidden_size=10, latent_size=2):
+        super().__init__()
+        self.input_size = input_size
+        self.hidden_size = hidden_size
+        self.latent_size = latent_size
+        self.dense1 = torch.nn.Linear(self.input_size, self.hidden_size)
+        self.dense2 = torch.nn.Linear(self.hidden_size, self.latent_size)
+        self.relu = torch.nn.ReLU()
+
+    def forward(self, x):
+        return self.relu(self.dense2(self.relu(self.dense1(x))))
+
+
+if __name__ == "__main__":
+    # Dataset
+    x_train, y_train = load_iris(return_X_y=True)
+    train_ds = NumpyDataset(x_train, y_train)
+
+    # Dataloaders
+    train_loader = DataLoader(train_ds, num_workers=0, batch_size=150)
+
+    # Hyperparameters
+    hparams = dict(
+        input_dim=x_train.shape[1],
+        nclasses=3,
+        prototypes_per_class=1,
+        prototype_initializer="stratified_mean",
+        lr=0.01,
+    )
+
+    # Initialize the model
+    model = SiameseGLVQ(hparams,
+                        backbone_module=Backbone,
+                        data=[x_train, y_train])
+
+    # Model summary
+    print(model)
+
+    # Callbacks
+    vis = VisualizationCallback(x_train, y_train)
+
+    # Setup trainer
+    trainer = pl.Trainer(max_epochs=100, callbacks=[vis])
+
+    # Training loop
+    trainer.fit(model, train_loader)

prototorch/models/glvq.py

@@ -68,8 +68,8 @@ class GLVQ(pl.LightningModule):
     #     self.log("train_acc_epoch", self.train_acc.compute())
 
     def predict(self, x):
+        # model.eval()  # ?!
         with torch.no_grad():
-            # model.eval()  # ?!
             d = self(x)
             plabels = self.proto_layer.prototype_labels
             y_pred = wtac(d, plabels)
@@ -77,8 +77,52 @@ class GLVQ(pl.LightningModule):
 
 
 class ImageGLVQ(GLVQ):
-    """GLVQ model that constrains the prototypes to the range [0, 1] by
+    """GLVQ for training on image data.
+
+    GLVQ model that constrains the prototypes to the range [0, 1] by
     clamping after updates.
     """
     def on_train_batch_end(self, outputs, batch, batch_idx, dataloader_idx):
         self.proto_layer.prototypes.data.clamp_(0.0, 1.0)
+
+
+class SiameseGLVQ(GLVQ):
+    """GLVQ in a Siamese setting.
+
+    GLVQ model that applies an arbitrary transformation on the inputs and the
+    prototypes before computing the distances between them. The weights in the
+    transformation pipeline are only learned from the inputs.
+    """
+    def __init__(self,
+                 hparams,
+                 backbone_module=torch.nn.Identity,
+                 backbone_params={},
+                 **kwargs):
+        super().__init__(hparams, **kwargs)
+        self.backbone = backbone_module(**backbone_params)
+        self.backbone_dependent = backbone_module(
+            **backbone_params).requires_grad_(False)
+
+    def sync_backbones(self):
+        master_state = self.backbone.state_dict()
+        self.backbone_dependent.load_state_dict(master_state, strict=True)
+
+    def forward(self, x):
+        self.sync_backbones()
+        protos = self.proto_layer.prototypes
+
+        latent_x = self.backbone(x)
+        latent_protos = self.backbone_dependent(protos)
+
+        dis = euclidean_distance(latent_x, latent_protos)
+        return dis
+
+    def predict_latent(self, x):
+        # model.eval()  # ?!
+        with torch.no_grad():
+            protos = self.proto_layer.prototypes
+            latent_protos = self.backbone_dependent(protos)
+            d = euclidean_distance(x, latent_protos)
+            plabels = self.proto_layer.prototype_labels
+            y_pred = wtac(d, plabels)
+        return y_pred.numpy()