The code is the following
crossval <- function(data, lambda=0, ytrans=function(x) x)
I wanna know what function (x) in a function parameter list mean?if calling the same function again and again or something? If so is it possible to call the function crossval itself?Isthe variable ytrans necessary?cannot we just call the function(x) in the function body?
@duffymo covered it, but here's a bit longer explanation.
What you see there is called an anonymous function. The function basically returns the same objects (= does nothing). This could also be written explicitly as a named function
newFunction <- function(x) {
x
}
which would then be
crossval <- function(data, lambda=0, ytrans = newFunction)
This is the default value, like in lambda=0, except the default value is a function itself.
newFunction squares x then you could do foo <- function( x , y ) y(x) and foo( 2 , newFunction ) returns 4. +1
Default function is one that returns the x value that it's passed. If you don't supply one, that's the function that will be used.