I am using gbm package to create a simple gradient boosting machine model. I would like to calculate some statistics from predicted vs. actual (such as GINI ratio, SSE). I read the vignette as well as manual, but could not find out where to get predicted values from output of this procedure. (Of course I can use gbm to predict on the train set, but it takes me a long time to run .predict).
Maybe this can help you: