 # R ifelse() Function

In this tutorial, you will learn about the ifelse() function in R with examples.

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

Most of the functions in R take a vector as input and return a vectorized output. Similarly, the vector equivalent of the traditional `if...else` block is the `ifelse()` function.

The syntax of the `ifelse()` function is:

``ifelse(test_expression, x, y)``

The output vector has the element x if the output of the `test_expression` is `TRUE`. If the output is `FALSE`, then the element in the output vector will be y.

## Example 1: ifelse() Function for Odd/Even Numbers

``````# input vector
x <- c(12, 9, 23, 14, 20, 1, 5)

# ifelse() function to determine odd/even numbers
ifelse(x %% 2 == 0, "EVEN", "ODD")``````

Output

` "EVEN" "ODD"  "ODD"  "EVEN" "EVEN" "ODD"  "ODD" `

In this program, we have defined a vector x using the `c()` function in R. The vector contains a few odd and even numbers.

We then used the `ifelse()` function which takes the vector x as an input. A logical operation is then performed on x to determine if the elements are odd or even.

For each element in the vector, if the `test_expression` evaluates to `TRUE`, then the corresponding output element is "`EVEN`", else it's "`ODD`".

## Example 2: ifelse() Function for Pass/Fail

``````# 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")``````

Output

` "PASS" "PASS" "FAIL" "PASS" "PASS" "FAIL" "PASS" "FAIL"`

This program determines if the students have passed or failed based on a condition. Here, if the marks in the vector are less than 40, then the student is considered to have failed.