Let's use one more callback. This time, we will build a custom callback that computes Receiver Operating Characteristic Area Under the Curve (ROC AUC) at the end of every epoch, on both training and testing sets.
Creating a custom callback in Keras is actually really simple. All we need to do is create a class, inherent Callback, and override the method we need. Since we want to calculate the ROC AUC score at the end of each epoch, we will override on _epoch_end:
from keras.callbacks import Callbackclass RocAUCScore(Callback): def __init__(self, training_data, validation_data): self.x = training_data[0] self.y = training_data[1] self.x_val = validation_data[0] self.y_val = validation_data[1] super(RocAUCScore, ...
