update

Author: MorvanZhou

README.md

@@ -56,6 +56,11 @@ You can watch my [Youtube channel](https://www.youtube.com/channel/UCdyjiB5H8Pu7
     <img class="course-image" src="https://morvanzhou.github.io/static/results/torch/1-1-3.gif">
 </a>
 
+### [CNN](https://github.com/MorvanZhou/PyTorch-Tutorial/blob/master/tutorial-contents/401_CNN.py)
+<a href="https://github.com/MorvanZhou/PyTorch-Tutorial/blob/master/tutorial-contents/401_CNN.py">
+    <img class="course-image" src="https://morvanzhou.github.io/static/results/torch/4-1-2.gif" >
+</a>
+
 ### [RNN](https://github.com/MorvanZhou/PyTorch-Tutorial/blob/master/tutorial-contents/403_RNN_regressor.py)
 
 <a href="https://github.com/MorvanZhou/PyTorch-Tutorial/blob/master/tutorial-contents/403_RNN_regressor.py">

tutorial-contents/401_CNN.py

@@ -74,7 +74,7 @@ def forward(self, x):
         x = self.conv2(x)
         x = x.view(x.size(0), -1)           # flatten the output of conv2 to (batch_size, 32 * 7 * 7)
         output = self.out(x)
-        return output
+        return output, x    # return x for visualization
 
 
 cnn = CNN()
@@ -83,24 +83,53 @@ def forward(self, x):
 optimizer = torch.optim.Adam(cnn.parameters(), lr=LR)   # optimize all cnn parameters
 loss_func = nn.CrossEntropyLoss()                       # the target label is not one-hotted
 
+# following function (plot_with_labels) is for visualization, can be ignored if not interested
+from matplotlib import cm
+try:
+    from sklearn.manifold import TSNE
+    HAS_SK = True
+except:
+    HAS_SK = False
+    print('Please install sklearn for layer visualization')
+def plot_with_labels(lowDWeights, labels):
+    plt.cla()
+    X, Y = lowDWeights[:, 0], lowDWeights[:, 1]
+    for x, y, s in zip(X, Y, labels):
+        c = cm.rainbow(int(255 * s / 9))
+        plt.text(x, y, s, backgroundcolor=c, fontsize=9)
+    plt.xlim(X.min(), X.max())
+    plt.ylim(Y.min(), Y.max())
+    plt.title('Visualize last layer')
+    plt.show()
+    plt.pause(0.01)
+
+plt.ion()
+
 # training and testing
 for epoch in range(EPOCH):
     for step, (x, y) in enumerate(train_loader):   # gives batch data, normalize x when iterate train_loader
         b_x = Variable(x)   # batch x
         b_y = Variable(y)   # batch y
 
-        output = cnn(b_x)               # cnn output
+        output = cnn(b_x)[0]               # cnn output
         loss = loss_func(output, b_y)   # cross entropy loss
         optimizer.zero_grad()           # clear gradients for this training step
         loss.backward()                 # backpropagation, compute gradients
         optimizer.step()                # apply gradients
 
         if step % 50 == 0:
-            test_output = cnn(test_x)
+            test_output, last_layer = cnn(test_x)
             pred_y = torch.max(test_output, 1)[1].data.squeeze()
             accuracy = sum(pred_y == test_y) / float(test_y.size(0))
             print('Epoch: ', epoch, '| train loss: %.4f' % loss.data[0], '| test accuracy: %.2f' % accuracy)
-
+            if HAS_SK:
+                # Visualization of trained flatten layer (T-SNE)
+                tsne = TSNE(perplexity=30, n_components=2, init='pca', n_iter=5000)
+                plot_only = 500
+                low_dim_embs = tsne.fit_transform(last_layer.data.numpy()[:plot_only, :])
+                labels = test_y.numpy()[:plot_only]
+                plot_with_labels(low_dim_embs, labels)
+plt.ioff()
 
 # print 10 predictions from test data
 test_output = cnn(test_x[:10])