This package customized the original BART package for warm start. It can load fitted trees from XBART and run the regular BART MCMC sampler.
Besides, this package provides multinomial classification BART, see the function mlbart.
The main function fitting warm-start BART is wbart_ini for regression, and mlbart_ini for classification trees. See the demo script in the XBART package for details, tests/test_regression_warmstart.R and tests/test_classification_warmstart.R.