How to use F1 Score with Keras model?

For your implementation of f1_score to work I had to switch y_true and y_pred in the function declaration. P.S.: for those who asked: K = keras.backend

When you load the model, you have to supply that metric as part of the custom_objects bag.

Try it like this:

from keras import models 
model = models.load_model(model_path, custom_objects= {'f1_score': f1_score})

Where f1_score is the function that you passed through compile.