library(rpart) system.time(A <-read.table(file="airline220M.csv", sep=",", header=T, nrows=220000001,colClasses=c(rep("NULL",3), "factor", rep("NULL", 10), "numeric", "numeric", rep("NULL", 13)))) system.time(A$Late <- A$ArrDelay > 10) system.time(A$Late <- as.factor(A$Late)) gc(T) system.time(result <- rpart(Late ~ DepDelay + DayOfWeek, data = A)) gc(T) Sys.time()