diff --git a/R-package/demo/00Index b/R-package/demo/00Index index 43df3ae61..0112eb9e1 100644 --- a/R-package/demo/00Index +++ b/R-package/demo/00Index @@ -6,5 +6,5 @@ generalized_linear_model Generalized Linear Model cross_validation Cross validation create_sparse_matrix Create Sparse Matrix predict_leaf_indices Predicting the corresponding leaves -early_Stopping Early Stop in training +early_stopping Early Stop in training poisson_regression Poisson Regression on count data diff --git a/R-package/demo/early_stopping.R b/R-package/demo/early_stopping.R new file mode 100644 index 000000000..34dfebc0b --- /dev/null +++ b/R-package/demo/early_stopping.R @@ -0,0 +1,39 @@ +require(xgboost) +# load in the agaricus dataset +data(agaricus.train, package='xgboost') +data(agaricus.test, package='xgboost') +dtrain <- xgb.DMatrix(agaricus.train$data, label = agaricus.train$label) +dtest <- xgb.DMatrix(agaricus.test$data, label = agaricus.test$label) +# note: for customized objective function, we leave objective as default +# note: what we are getting is margin value in prediction +# you must know what you are doing +param <- list(max.depth=2,eta=1,nthread = 2, silent=1) +watchlist <- list(eval = dtest) +num_round <- 20 +# user define objective function, given prediction, return gradient and second order gradient +# this is loglikelihood loss +logregobj <- function(preds, dtrain) { + labels <- getinfo(dtrain, "label") + preds <- 1/(1 + exp(-preds)) + grad <- preds - labels + hess <- preds * (1 - preds) + return(list(grad = grad, hess = hess)) +} +# user defined evaluation function, return a pair metric_name, result +# NOTE: when you do customized loss function, the default prediction value is margin +# this may make buildin evalution metric not function properly +# for example, we are doing logistic loss, the prediction is score before logistic transformation +# the buildin evaluation error assumes input is after logistic transformation +# Take this in mind when you use the customization, and maybe you need write customized evaluation function +evalerror <- function(preds, dtrain) { + labels <- getinfo(dtrain, "label") + err <- as.numeric(sum(labels != (preds > 0)))/length(labels) + return(list(metric = "error", value = err)) +} +print ('start training with early Stopping setting') +# training with customized objective, we can also do step by step training +# simply look at xgboost.py's implementation of train +bst <- xgb.train(param, dtrain, num_round, watchlist, logregobj, evalerror, maximize = FALSE, + early.stop.round = 3) +bst <- xgb.cv(param, dtrain, num_round, nfold=5, obj=logregobj, feval = evalerror, + maximize = FALSE, early.stop.round = 3) diff --git a/R-package/demo/runall.R b/R-package/demo/runall.R index 2ea4c446e..7311ec95e 100644 --- a/R-package/demo/runall.R +++ b/R-package/demo/runall.R @@ -7,5 +7,5 @@ demo(generalized_linear_model) demo(cross_validation) demo(create_sparse_matrix) demo(predict_leaf_indices) -demo(early_Stopping) +demo(early_stopping) demo(poisson_regression)