I'm following this Keras tutorial that explain how to write your custom train_step() function while still being able to call model.fit() in order to train your model:
https://keras.io/guides/customizing_what_happens_in_fit/
model.fit() should be able to support validation_data but I can't understand where to write code that compute custom metrics and custom losses for validation_data. I've decided to write a custom loop but I would like to use fit.
Any ideas?