In R, we will often perform a task based on a condition. For example, if we are analyzing data for the summer, then we will only want to look at data that falls in June, July, and August.

We can perform a task based on a condition using an if statement:

if (TRUE) {
  print('This message will print!')
} 

Notice in the example above, we have an if statement. The if statement is composed of:

• The if keyword followed by a set of parentheses () which is followed by a code block, or block statement, indicated by a set of curly braces {}.
• Inside the parentheses (), a condition is provided that evaluates to TRUE or FALSE.
• If the condition evaluates to true, the code inside the curly braces {} runs, or executes.
• If the condition evaluates to false, the code inside the block won’t execute.

Knowing how to use if statements will help you introduce logic in your data analysis. There is also a way to add an else statement. An else statement must be paired with an if statement, and together they are referred to as an if…else statement.

if (TRUE) {
   print("Go to sleep!")
} else {
   print("Wake up!")
}

In the example above, the else statement:

• Uses the else keyword following the code block of an if statement.
• Has a code block that is wrapped by a set of curly braces {}.
• The code inside the else statement code block will execute when the if statement’s condition evaluates to false. These if…else statements allow us to automate solutions to yes-or-no questions, also known as binary decisions.