Does anyone know if the error being generated when trying to predict test set data in the Easy Uplift Tree package is something fixable by the user or is this a bug in the program making the package essentially non-operable? This is from the package documentation and fails on the last step of applying the model to the test set: install.packages("EasyUpliftTree") library(EasyUpliftTree) library(survival) data(colon) #APPEARS TO WORK sample.data <- na.omit(colon[colon$rx != "Lev" & colon$etype == 2, ]) treat <- ifelse(sample.data$rx == "Lev+5FU", 1, 0) y <- ifelse(sample.data$status == 0, 1, 0) x <- sample.data[, c(4:9, 11:14)] x$v1 <- factor(x$sex) x$v2 <- factor(x$obstruct) x$v3 <- factor(x$perfor) x$v4 <- factor(x$adhere) x$v5 <- factor(x$differ) x$v6 <- factor(x$extent) x$v7 <- factor(x$surg) x$v8 <- factor(x$node4) index <- 1:nrow(x) train.index <- index[(index%%2 == 0)] test.index <- index[index%%2 != 0] y.train <- y[train.index] x.train <- x[train.index, ] treat.train <- treat[train.index] y.test <- y[test.index] x.test <- x[test.index, ] treat.test <- treat[test.index] uplift.tree <- buildUpliftTree(y.train, treat.train, x.train) print(uplift.tree) #FAILS apply(1:nrow(x.test), function(i) classify(uplift.tree, x.test[i, ])) #Error in match.fun(FUN) : argument "FUN" is missing, with no default