Conditionals in R

Branching, and its vectorized alternative.

grade <- function(score) {
  if (score >= 90) {
    "A"
  } else if (score >= 80) {
    "B"
  } else {
    "F"
  }
}

marks <- sapply(c(95, 85, 40), grade)
vectorized <- ifelse(c(95, 85, 40) >= 80, "pass", "fail")

How it works

1. An if/else if chain returns the matching branch.
2. sapply applies the function across a vector.
3. ifelse is the vectorized form, testing every element.

Keywords and builtins used here

• c
• else
• function
• if
• ifelse
• sapply

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Step 1 of 5 in Flow & functions, step 5 of 20 in Language basics.

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Conditionals in other languages

• C