Features in collaborative filtering

Hello, I understood that in CF weights, biases and features are all parameters and we minimize the cost function with respect to all three of them. But I don`t understand how we determine the amount of features used in the model. How do we know what should be the length of each x vector ?

Hello @saba_odisharia

I recommend you to read this answer to a very similar question of yours.

Cheers,
Raymond