Can I specify the root node splitting feature in XGBoost?

Just what the title says. Suppose I know the feature that I want to be used for splitting for the root node in a tree model in XGBoost; is there a way for me to tell XGBoost to split on this feature at the root node?

• I don't know the answer to your question, but I'm curious why you want to do this. – tom Oct 22 '19 at 20:42
• @tom I have a categorical feature that can take one of several values, and I'm considering whether I want to make a single model and let XGBoost deal with this feature on its own, or if I want to make a different model for each possible value of this feature. The latter option is tedious and time consuming, so if I can tell XGBoost just to always split on that feature first then that should serve as an easy way of testing the "many different models" case. – bgav Oct 22 '19 at 21:18

xgb.train(…,xgb_model=model_to_start_from)