在練習用VGG16做分類，我用這篇的程式碼下去改的https://reurl.cc/RvvG9x VGG16的部分和他這篇不一樣不是用預設而是用寫的 問題在於，進行訓練的時候Testing acc一直都是0.500，而acc都在0.5附近上下跳動 也就是說好像根本沒有學習到 進行訓練的程式碼如下: (基本與那篇相同，這裡只是將原文中的C改成model，並且把label的type改成tensor) if __name__ == '__main__': for epoch in range(epochs): start_time = time.time() iter = 0 correct_train, total_train = 0, 0 correct_test, total_test = 0, 0 train_loss_C = 0.0 model.train() # 設定 train 或 eval print('epoch: ' + str(epoch + 1) + ' / ' + str(epochs)) # --------------------------- # Training Stage # --------------------------- for i, (x, label) in enumerate(train_dataloader) : label = label.type(torch.LongTensor) x, label = x.to(device), label.to(device) optimizer_C.zero_grad() # 清空梯度 train_output = model(x) train_loss = criterion(train_output, label) # 計算 loss train_loss.backward() # 將 loss 反向傳播 optimizer_C.step() # 更新權重 # 計算訓練資料的準確度 (correct_train / total_train) _, predicted = torch.max(train_output.data, 1) total_train += label.size(0) correct_train += (predicted == label).sum() train_loss_C += train_loss.item() iter += 1 print('Training epoch: %d / loss_C: %.3f | acc: %.3f' % \ (epoch + 1, train_loss_C / iter, correct_train / total_train)) # -------------------------- # Testing Stage # -------------------------- model.eval() # 設定 train 或 eval for i, (x, label) in enumerate(test_dataloader) : with torch.no_grad(): label = label.type(torch.LongTensor) x, label = x.to(device), label.to(device) test_output = model(x) test_loss = criterion(test_output, label) # 計算 loss # 計算測試資料的準確度 (correct_test / total_test) _, predicted = torch.max(test_output.data, 1) total_test += label.size(0) correct_test += (predicted == label).sum() print('Testing acc: %.3f' % (correct_test / total_test)) train_acc.append(100 * (correct_train / total_train).cpu()) # training accuracy test_acc.append(100 * (correct_test / total_test).cpu()) # testing accuracy loss_epoch_C.append((train_loss_C / iter)) # loss end_time = time.time() print('Cost %.3f(secs)' % (end_time - start_time)) 指定epochs只跑3次，得到以下結果: epoch: 1 / 3 Training epoch: 1 / loss_C: 0.693 | acc: 0.514 Testing acc: 0.500 Cost 21.822(secs) epoch: 2 / 3 Training epoch: 2 / loss_C: 0.693 | acc: 0.475 Testing acc: 0.500 Cost 23.002(secs) epoch: 3 / 3 Training epoch: 3 / loss_C: 0.693 | acc: 0.476 Testing acc: 0.500 Cost 22.669(secs) --

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