Report Keras model evaluation metrics every 10 epochs?

Question

I'd like to know the specificity and sensitivity of my model. Currently, I'm evaluating the model after all epochs are finished:

from sklearn.metrics import confusion_matrix

predictions = model.predict(x_test)
y_test = np.argmax(y_test, axis=-1)
predictions = np.argmax(predictions, axis=-1)
c = confusion_matrix(y_test, predictions)
print('Confusion matrix:\n', c)
print('sensitivity', c[0, 0] / (c[0, 1] + c[0, 0]))
print('specificity', c[1, 1] / (c[1, 1] + c[1, 0]))

The disadvantage of this approach, is I only get the output I care about when training has finished. Would prefer to get metrics every 10 epochs or so.

BTW: Tried with the metrics=[] here. Possibly a callback is the way to go?

Answer 1

A custom Callback would be a nice solution giving you enough control over the training procedure. Something along the lines of:

class SensitivitySpecificityCallback(Callback):
    def on_epoch_end(self, epoch, logs=None):
        if epoch % 10 == 1:
            x_test = self.validation_data[0]
            y_test = self.validation_data[1]
            # x_test, y_test = self.validation_data
            predictions = self.model.predict(x_test)
            y_test = np.argmax(y_test, axis=-1)
            predictions = np.argmax(predictions, axis=-1)
            c = confusion_matrix(y_test, predictions)

            print('Confusion matrix:\n', c)
            print('sensitivity', c[0, 0] / (c[0, 1] + c[0, 0]))
            print('specificity', c[1, 1] / (c[1, 1] + c[1, 0]))

where epoch is the epoch number and logs contain the usual metrics + loss the model trains.

Then run with:

model.fit(x_train, y_train,
          batch_size=batch_size,
          epochs=epochs,
          verbose=1,
          shuffle='batch',
          validation_data=(x_test, y_test),
          callbacks=[SensitivitySpecificityCallback()])

NOTE: if you don't like how your model is training based on your metrics you can cut the training short with:

self.model.stop_training = True

which will stop the training for you.