How to plot confusion matrix for prefetched dataset in Tensorflow

Question

I was trying to plot a confusion matrix for my image classifier with the following code but I got an error message: 'PrefetchDataset' object has no attribute 'classes'

Y_pred = model.predict(validation_dataset)
y_pred = np.argmax(Y_pred, axis=1)

print('Confusion Matrix')
print(confusion_matrix(validation_dataset.classes, y_pred)) # ERROR message generated

PrefetchDataset' object has no attribute 'classes'

Answer 1

This code will work with shuffled tf.data.Dataset

y_pred = []  # store predicted labels
y_true = []  # store true labels

# iterate over the dataset
for image_batch, label_batch in dataset:   # use dataset.unbatch() with repeat
   # append true labels
   y_true.append(label_batch)
   # compute predictions
   preds = model.predict(image_batch)
   # append predicted labels
   y_pred.append(np.argmax(preds, axis = - 1))

# convert the true and predicted labels into tensors
correct_labels = tf.concat([item for item in y_true], axis = 0)
predicted_labels = tf.concat([item for item in y_pred], axis = 0)