User Defined Functions

Part of what makes R so powerful is that you can write your own functions to make your life easier.

my_func <- function(parameter) { 
  rep(parameter,5)
  }

my_func("cats")

## [1] "cats" "cats" "cats" "cats" "cats"

a better example

cook_dinner <- function(ingredients) {
  for (i in ingredients) {
    if (i == "pasta") {
      print("for pasta we need to find the strainer")
    }
    else if (i == "salmon") { 
      print("for salmon we need to get a lemon")
      }
    else if (i == "baked potatoes") {
      print("Baked potato? we need butter")
    }
    else {
      cat("I ain't got ", i, ". Ordering a pizza instead.")
    } 
  }
}

cook_dinner(c("pasta","salmon","cheese"))

## [1] "for pasta we need to find the strainer"
## [1] "for salmon we need to get a lemon"
## I ain't got  cheese . Ordering a pizza instead.