set_response_idx 1965 apps/traincascade/old_ml.hpp     void set_response_idx( int idx ); // old response become predictors, new response_idx = idx
set_response_idx  115 modules/ml/test/test_gbttest.cpp             data->set_response_idx(57);
set_response_idx  120 modules/ml/test/test_gbttest.cpp             data->set_response_idx(13);