PyTorch Confusion Matrix Plot
I have met a problem for plotting a confusion matrix. The upper and lower lines are put incorrectly.
When I plot it, it looks like this.



I think there is nothing wrong with my code, since I took it from this YouTube exactly. 

def plot_confusion_matrix(cm, classes,
                          normalize=False,
                          title='Confusion matrix',
                          cmap=plt.cm.Blues):
    """
    This function prints and plots the confusion matrix.
    Normalization can be applied by setting `normalize=True`.
    """
    if normalize:
        cm = cm.astype('float') / cm.sum(axis=1)[:, np.newaxis]
        print("Normalized confusion matrix")
    else:
        print('Confusion matrix, without normalization')

    print(cm)

    plt.imshow(cm, interpolation='nearest', cmap=cmap)
    plt.title(title)
    plt.colorbar()
    tick_marks = np.arange(len(classes))
    plt.xticks(tick_marks, classes, rotation=45)
    plt.yticks(tick_marks, classes)

    fmt = '.2f' if normalize else 'd'
    thresh = cm.max() / 2.
    for i, j in itertools.product(range(cm.shape[0]), range(cm.shape[1])):
        plt.text(j, i, format(cm[i, j], fmt),
                 horizontalalignment="center",
                 color="white" if cm[i, j] &gt; thresh else "black")

    plt.tight_layout()
    plt.ylabel('True label')
    plt.xlabel('Predicted label')



# Graphical analytics
cm = confusion_matrix(train_set.targets, train_preds.argmax(dim=1))
names = ('T-shirt/top','Trouser','Pullover','Dress','Coat','Sandal','Shirt','Sneaker','Bag','Ankle boot')
plt.figure(figsize=(10,10))
plot_confusion_matrix(cm, names)



You can change manually the range of the y axis.

plt.ylim(-0.5, len(names) - 0.5)


For some reason heuristic for estimating the axis range does not get that you are not only interested in the points you are plotting but also in the (-0.5; +0.5) surrounding on both axes.

The lowest points have y coordinate 0, the top-most points have y coordinate len(names) - 1.
