r - custom metric using ROCR package in caret -
here minimal example of problem. want use recall performance metric in caret
library(caret) set.seed(1234) x <- matrix(rnorm(10),nrow=5,ncol=2 ) y <- factor(c("y","n","y","y","n")) my.metric <- function (data, lev = null, model = null) { out <- rocr::performance(rocr::prediction(data$pred, as.numeric(data$obs)-1,"rec")) names(out) <- "rec" out } mycontrol <- traincontrol(summaryfunction = my.metric, method="repeatedcv", number=10, repeats=2) fit <- train(y=y,x=x, metric = "rec",method="gbm", trcontrol = mycontrol) however, error
error in rocr::prediction(data$pred, as.numeric(data$obs) - 1, "rec") : format of predictions invalid.
i haven't used package in while based on example in ?prediction, need pass class probabilities (and train doesn't generate these unless use option classprobs = true in traincontrol) in argument predictions. once have done that, use proper column of data input prediction function.
also, should read the paper on subject because think need call performance recall.
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