Hi,
I wrote a dummy function that passes a dataset to tree() as the
following:
test.func <- function(training.data){
tr <- tree(type~., data = training.data)
tr
}
Then I run the function under R
test.func(MyData)
Error in model.frame.default(formula = type ~ ., data = training.data) :
Object "training.data" not found
MyData resides in the working environment, while training.data does not.
R manual
claims that scoping of free variables are "lexical" (Introduction to R,
chapter 10.7).
I take that it means that in evaluating the expression
tree(type~., data=training.data) ,
R will look in the scope of the function test.func, therefore
discovering "training.data"
as a "formal parameter". But it seemed that I misunderstood something
here.
I also made a global variable
training.data <- MyData
and run
test.func(MyData)
The function works fine without complaints.
Can someone please help with this matter?
Jonathan
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