卷积神经网络的训练和测试

Question

I would like to know at what stage testing dataset is used CNNs? Is it used after completion of each batch or one epoch during training or is it used after completion of all the epochs? I am a bit confused as to how these two processes run together? Similarly gradient updation is done after each batch or each epoch?

model.fit_generator(
aug.flow(x_train, y_train, batch_size=BATCH_SIZE),
validation_data=(x_test, y_test),
steps_per_epoch=len(x_train) // BATCH_SIZE,
epochs=EPOCHS, verbose=1, callbacks = callbacks)

From fit_generator it is only clear that images are loaded batch by batch onto memory.

Answer 1

Keras is using validation datasets in the end of every epoch (if you didn't change validation_freq in the fit function). Each epoch your model trains on the whole train dataset and later evaluates itself on the validation dataset