{
  "objective": "rank:ndcg",
  "eval_metric": "ndcg",
  "tree_method": "hist",
  "eta": 0.05,
  "max_depth": 6,
  "subsample": 0.8,
  "colsample_bytree": 0.8,
  "gamma": 0.1,
  "reg_alpha": 0.1,
  "reg_lambda": 1.0
}