§2024-12-04

x <- 3
# check if x is greater than 0
if (x > 0) {
  print("The number is positive")
}

age <- 15
# check if age is greater than 18
if (age > 18) {
  print("You are eligible to vote.")
} else {
  print("You cannot vote.")
}

x <- 20
# check if x is positive
if (x > 0) {
  # check if x is even or odd
  if (x %% 2 == 0) {
    print("x is a positive even number")
  } else {
    print("x is a positive odd number")
  }
# execute if x is not positive
} else {
  # check if x is even or odd
  if (x %% 2 == 0) {
    print("x is a negative even number")
  } else {
    print("x is a negative odd number")
  }
}

In R, the ifelse() function is a shorthand vectorized alternative to the standard if...else statement.

# A vector is the basic data structure in R that stores data of similar types. 

# input vector
x <- c(12, 9, 23, 14, 20, 1, 5)
# ifelse() function to determine odd/even numbers
ifelse(x %% 2 == 0, "EVEN", "ODD")

# [1] "EVEN" "ODD"  "ODD"  "EVEN" "EVEN" "ODD"  "ODD" 

# input vector of marks
marks <- c(63, 58, 12, 99, 49, 39, 41, 2)
# ifelse() function to determine pass/fail
ifelse(marks < 40, "FAIL", "PASS")

# [1] "PASS" "PASS" "FAIL" "PASS" "PASS" "FAIL" "PASS" "FAIL"