Conditionals

If / Else

R uses if, else if, and else for conditional execution:

x <- 10

if (x > 0) {
  cat("positive\n")
} else if (x < 0) {
  cat("negative\n")
} else {
  cat("zero\n")
}

The condition must be in parentheses. The braces are required for multi-line blocks and recommended even for single lines.

Comparison Operators

Logical Operators

Use && and \|\| for scalar comparisons (in if statements). Use & and \| for element-wise vector operations.

The ifelse() Function

For vectorized conditional operations, use ifelse():

x <- c(1, -2, 3, -4, 5)
result <- ifelse(x > 0, "pos", "neg")
cat(result, "\n")  # pos neg pos neg pos

Your Task

Write a function classify that takes a number and returns "positive", "negative", or "zero". Call it with 5, -3, and 0, printing each result.