8 Functions

8.0.1 Function Overview

  • Functions are objects and are assigned to names, just like data.

    myFunction = function(argument1,argument2) {
  expression1
  expression2
}

  • We write functions for anything we need to do again and again.

  • You may test your commands interactively at first, and then use the history() feature and an editor to create the function.

  • It is wise to include a comment at the start of each function to say what it does and to document functions of more than a few lines.

8.0.2 Example Functions

add1 = function(x) {
    # this function adds one to the first argument and returns it
    x + 1
}
add1(17)
## [1] 18
add1(c(17,18,19,20))
## [1] 18 19 20 21

You can use the edit() function to make changes to a function. The following command will open a window, allow you to make changes, and assign the result to a new function, add2.

add2 = edit(add1)