Easiest way to get version info of a XGBoost model through C++ interface

[yunmengxie]

Hi there, I have a question regarding retrieve the version info of a XGBoost model.

Say that I have a pre-trained XGBoost model saved in bst/json format, what would be the easiest way to get the XGBoost library version that trained this model?

I checked through api methods in C++ interface, looks like these isn't an existing api to get the version info, any recommendation to achieve this?

[trivialfis]

Hi, the version recorded by XGBoost is the last version that saved the model, instead of the version that trained the model. Meaning, if you train a model with XGBoost 1.5, load the model and save it again using 1.7, then the recorded version will be changed to 1.7.

Now that this is clear, you can see the version in the output JSON file.

[yunmengxie]

Thanks for the answer! What if the model is trained with XGBoost 1.5 and saved in bst(instead of json) format, how could I tell this model is trained with 1.5 when loading it using 1.7?

[trivialfis]

There's no easy way to do that with the old binary format. One of the reasons for #7547 .