If Statement in R

In this tutorial, we will learn about if statements in R. We will cover the basics of conditional execution using if statements.

What is an If statement

An if statement is a conditional statement that executes a block of code if a specified condition is true.

Syntax

The syntax for the if statement in R is:

if (condition) {
    # Code block to execute if condition is true
}

The if statement evaluates the specified condition. If the condition is true, the code block inside the if statement is executed; otherwise, it is skipped.

The following is the flowchart of how execution flows from start to the end of an if statement.

Flowchart of If Statement

Example 1: Checking if a Number is Even

In R, checking if a number is even can be done using the modulo operator (%), where the remainder when divided by 2 is zero.

For example,

  1. Declare a variable num.
  2. Assign a value to num.
  3. Use an if statement to check if num is even.
  4. Print a message indicating whether num is even or not.

R Program

num <- 10
if (num %% 2 == 0) {
    print(paste(num, 'is even.'))
}

Output

[1] "10 is even."

Example 2: Checking if a String Starts with a Specific Value

In R, checking if a string starts with a specific value can be done using the startsWith() function. The function returns a boolean value, which can be used as a condition in the if statement.

For example,

  1. Declare a variable str.
  2. Assign a value to str.
  3. Use an if statement to check if str starts with a specific value.
  4. Print a message indicating the result of the check.

R Program

str <- 'Hello, world!'
if (startsWith(str, 'Hello')) {
    print('String starts with "Hello".')
}

Output

[1] "String starts with \"Hello\"."

Example 3: Checking if a Number is Positive

In R, checking if a number is positive within an if statement involves evaluating the condition where the number is greater than zero using the greater than operator (>).

For example,

  1. Declare a variable num.
  2. Assign a value to num.
  3. Use an if statement to check if num is positive.
  4. Print a message indicating whether num is positive or not.

R Program

num <- -5
if (num > 0) {
    print(paste(num, 'is positive.'))
}

Output