Hi
I normally use package data.table but today was doing some base R coding. Had a problem for a bit which I finally resolved. I was attempting to separate a data frame between train and test sets, and in base R was using the "!" to exclude training set indices from the data frame. All I was getting was zero observations. Changed to using "-" and it worked. I recalled that in data.table the "!" function worked, so created this little bit of code. # Base R Functions str(mtcars) train_indices <- sample(nrow(mtcars), round(0.75*nrow(mtcars))) train <- mtcars[train_indices,] mode(train_indices); class(train_indices) test <- mtcars[!train_indices,] # the "!" function returning 0 observations test_1 <- mtcars[-train_indices,] identical(test, test_1) # Using data.table package library(data.table) dt1 <- data.table(mtcars) train_indices <- sample(nrow(dt1), round(0.75*nrow(dt1))) train <- dt1[train_indices,] mode(train_indices); class(train_indices) test <- dt1[!train_indices,] # the "!" function test_1 <- dt1[-train_indices,] identical(test, test_1) The documentation appears to me to accept "!" in base, so do I have some kind of ridiculous error or ..?? Carl Sutton ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
