Global variables in R

问题

I am poking into the manuals, I wanted to ask the community: How can we set global variables inside a function?

回答1:

As Christian's answer with assign() shows, there is a way to assign in the global environment. A simpler, shorter (but not better ... stick with assign) way is to use the <<- operator, ie

    a <<- "new" 

inside the function.

回答2:

I found a solution for how to set a global variable in a mailinglist posting via assign:

a <- "old"
test <- function () {
   assign("a", "new", envir = .GlobalEnv)
}
test()
a  # display the new value

来源：https://stackoverflow.com/questions/1236620/global-variables-in-r