IF, ELSE, ELSE IF Statement in R

The if else statement

An if-else statement is a great tool for the developer trying to return an output based on a condition. In R, the syntax is:

if (condition) { Expr1 } else { Expr2 }

We want to examine whether a variable stored as “quantity” is above 20. If quantity is greater than 20, the code will print “You sold a lot!” otherwise Not enough for today.

Create vector quantity quantity <- 25 # Set the is-else statement if (quantity > 20) { print(‘You sold a lot!’) } else { print(‘Not enough for today’) }

Output:

[1] “You sold a lot!”

Note : Make sure you correctly write the indentations. Code with multiple conditions can become unreadable when the indentations are not in correct position.

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The else if statement

We can further customize the control level with the else if statement. With elif, you can add as many conditions as we want. The syntax is:

if (condition1) { expr1 } else if (condition2) { expr2 } else if (condition3) { expr3 } else { expr4 }

We are interested to know if we sold quantities between 20 and 30. If we do, then the pint Average day. If quantity is > 30 we print What a great day!, otherwise Not enough for today.

You can try to change the amount of quantity.

Create vector quantiy quantity <- 10 # Create multiple condition statement if (quantity <20) { print(‘Not enough for today’) } else if (quantity > 20 &quantity <= 30) { print(‘Average day’) } else { print(‘What a great day!’) }

Output:

[1] “Not enough for today”

Example 2:

VAT has different rate according to the product purchased. Imagine we have three different kind of products with different VAT applied:

Categories Products VAT
A Book, magazine, newspaper, etc… 8%
B Vegetable, meat, beverage, etc… 10%
C Tee-shirt, jean, pant, etc… 20%

We can write a chain to apply the correct VAT rate to the product a customer bought.

category <- ‘A’ price <- 10 if (category ==‘A’){ cat(‘A vat rate of 8% is applied.’,‘The total price is’,price *1.08) } else if (category ==‘B’){ cat(‘A vat rate of 10% is applied.’,‘The total price is’,price *1.10) } else { cat(‘A vat rate of 20% is applied.’,‘The total price is’,price *1.20) }

Output: