decision tree using rpart

[FIC]

excluded_variables <- c("target")

tree1 <- rpart(target ~ .,  
 data = dataset[, !(names(dataset) %in% excluded_variables)]

1. how do you interpret the code in the "data" argument"
2. what does the ! and % mean?

[cderv]

• ! is a negation operator

!TRUE
#> [1] FALSE
!FALSE
#> [1] TRUE
(x <- c(TRUE, FALSE))
#> [1]  TRUE FALSE
!x
#> [1] FALSE  TRUE

• %in% is an operator to check existence among a vector. It returns a logical value. If you use with ! you get the negation of the result. If you use a vector before %in% it will test each element

x <- c("A", "B")
"A" %in% x
#> [1] TRUE
"C" %in% x
#> [1] FALSE
!("B" %in% x)
#> [1] FALSE
c("A", "C") %in% x
#> [1]  TRUE FALSE

• names(dataset) %in% excluded_variables gets you a vector of logical, with TRUE for all the names of dataset that are in excluded_variables.
  Using ! before, you get TRUE, for all the names that are NOT in excluded_variables. This logical vector is used to select all the column of dataset except the ones in excluded_variables

Hopes it helps you understand your code.

[FIC]

thank you for the great response!

[cderv]

You're welcome. I think this is great questions when about getting better understanding of what we are doing.

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