I am working on a time$-$to$-$event dataset for survival analysis, which contains approximately $20,000$ samples and $100$ features, including both categorical and numerical data. I want to implement a model that combines Transformer with Cox proportional hazards to analyze this data.

How should I preprocess categorical and numerical features for input into a Transformer$-$Cox model? Could you provide a code example?

How can I structure a Transformer$-$based model for survival analysis and integrate it with the Cox model? Please include an example implementation.

What loss function should I use to train this model, and how can it be implemented?

How do I calculate evaluation metrics like C$-$index and Brier score for this type of model?