release code

Dassl.ProGrad.pytorch/dassl/engine/ssl/mean_teacher.py

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+import copy
+from torch.nn import functional as F
+
+from dassl.engine import TRAINER_REGISTRY, TrainerXU
+from dassl.metrics import compute_accuracy
+from dassl.modeling.ops.utils import sigmoid_rampup, ema_model_update
+
+
+@TRAINER_REGISTRY.register()
+class MeanTeacher(TrainerXU):
+    """Mean teacher.
+
+    https://arxiv.org/abs/1703.01780.
+    """
+
+    def __init__(self, cfg):
+        super().__init__(cfg)
+        self.weight_u = cfg.TRAINER.MEANTEA.WEIGHT_U
+        self.ema_alpha = cfg.TRAINER.MEANTEA.EMA_ALPHA
+        self.rampup = cfg.TRAINER.MEANTEA.RAMPUP
+
+        self.teacher = copy.deepcopy(self.model)
+        self.teacher.train()
+        for param in self.teacher.parameters():
+            param.requires_grad_(False)
+
+    def forward_backward(self, batch_x, batch_u):
+        input_x, label_x, input_u = self.parse_batch_train(batch_x, batch_u)
+
+        logit_x = self.model(input_x)
+        loss_x = F.cross_entropy(logit_x, label_x)
+
+        target_u = F.softmax(self.teacher(input_u), 1)
+        prob_u = F.softmax(self.model(input_u), 1)
+        loss_u = ((prob_u - target_u)**2).sum(1).mean()
+
+        weight_u = self.weight_u * sigmoid_rampup(self.epoch, self.rampup)
+        loss = loss_x + loss_u*weight_u
+        self.model_backward_and_update(loss)
+
+        global_step = self.batch_idx + self.epoch * self.num_batches
+        ema_alpha = min(1 - 1 / (global_step+1), self.ema_alpha)
+        ema_model_update(self.model, self.teacher, ema_alpha)
+
+        loss_summary = {
+            "loss_x": loss_x.item(),
+            "acc_x": compute_accuracy(logit_x, label_x)[0].item(),
+            "loss_u": loss_u.item(),
+        }
+
+        if (self.batch_idx + 1) == self.num_batches:
+            self.update_lr()
+
+        return loss_summary