Structuring Machine Learning Projects

Dear instructors,
I am studying week 2 of the course structuring machine learning projects in the lecture multitask learning. I am wondering how to write the y - label with question marks in the code

Hey @hailuu,
Welcome to the community. It’s not necessarily a question mark that you use. It’s just for intuition that Prof Andrew used a question mark. In practice, you can use a specific integer that you later interpret in your code as the absence of the label for that class. For instance, you can use -1 for all the labels of the categories which are absent. I hope this helps.