# 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:

`##  "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.

## 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:

`##  "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:

`# A vat rate of 8% is applied. The total price is 10.8`