I want to train an Artificial Neural Network on some data however some of the fields are optional, dependent upon the values contained in other fields. The data in these optional fields is missing, but correctly so. I am wondering how I should factor this into my neural network.
I feel like what I might need to do is turn certain inputs on/off dependent upon the values contained in other inputs but then I am wondering how this would affect weighting in the hidden layer. Could I have some kind of conditional hidden layer or something for only when these optional values are 'activated'?
What would be the standard approach to this? It seems surprisingly hard to find any material on this online!
Thanks in advance for any help!