how to specify variables with same name in two dataset within a function

Question

I have two dataset (training dataset and holdout dataset) which have the same variables. How can I specify the variables with same name in two datasets in a function? I tried the following, but it does not work.

function1 <- function (x, y, train, test){
  a<- train$x
  b<- train$y
  c<- test$x
  d<- test$y
 return(list(a,b,c,d))
}
function1(displacement, mpg, train_set, test_set)

The results are NULL for all four. Can anyone tell me how to achieve this?

"but it does not work" ... _what_ does not work? You never told us this. There is nothing wrong with the code in your function, and the two input data frames should be able to have columns with the same name. — Tim Biegeleisen, Mar 02 '19 at 15:03

score 0 · Answer 1 · answered Mar 02 '19 at 15:06

0

Replace $x with [[x]] and see.

function1 <- function (x, y, train, test){
  a<- train[[x]]
  b<- train[[y]]
  c<- test[[x]]
  d<- test[[y]]
 return(list(a,b,c,d))
}

answered Mar 02 '19 at 15:06

Sonny

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to handle NSE (give naked names without `"` to your function) you can do : `x <- as.character(substitute(x))` in your function, same for y, then use `[[` instead of `$` as in this solution – moodymudskipper Mar 02 '19 at 15:22

how to specify variables with same name in two dataset within a function

1 Answers1