The <<- operator can be used to assign a variable to the global environment. It's better to use the assign function than <<-. You probably shouldn't need to use <<- though - outputs needed from functions should be returned as objects in R.
Here's an example
f <- function(x) {
y <<- x * 2 # y outside the function
}
f(5) # y = 10
This is equivalent to
f <- function(x) {
x * 2
}
y <- f(5) # y = 10
With the assign function,
f <- function(x) {
assign('y', x*2 envir=.GlobalEnv)
}
f(5) # y = 10
