Lets say I build an xgboost model:
bst = xgb.train(param0, dtrain1, num_round, evals=[(dtrain, \"training\")])
Where:
You don't even have to load the model from the disk and retrain.
All you need to do is the same xgb.train
command with additional parameter: xgb_model= (either xgboost model full path name you've saved like in the question or a Booster object).
Example:
bst = xgb.train(param0, dtrain2, num_round, evals=[(dtrain, "training")], xgb_model='xgbmodel')
Good luck!