R If Else Conditions (original) (raw)

Last Updated : 18 Feb, 2026

In R programming, conditional statements allow a program to make decisions and execute different actions based on certain conditions. The if-else construct is a key conditional statement used to control the flow of code. Using these statements, you can handle different situations dynamically.

• **if Statement: Executes a block of code only when the condition is TRUE.
• **else Statement: Executes a block of code when the if condition is FALSE.

Syntax

if (condition) {

# code to execute if condition is TRUE

} else {

# code to execute if condition is FALSE

}

How if-else Statements Work in R

if-else statements control the flow of a program by executing different code blocks based on a condition.

if-else statement in R

• **Start of Control: Program execution reaches the if statement.
• **Condition Evaluation: The logical condition inside if is tested.
• **If TRUE: The code inside the if block is executed.
• **If FALSE: The code inside the else block is executed (if present).
• **Flow Exit: After executing the respective block, the program continues with the next statements outside the if-else.

**Example 1: Basic if-else

Here we implement a basic if-else statement in R to check whether a number is greater than or less than 10.

R `

x <- 5

Check value is less than or greater than 10

if(x > 10) { print(paste(x, "is greater than 10")) } else { print(paste(x, "is less than 10")) }

`

**Output

[1] "5 is less than 10"

Here x is initialized to 5, the condition x > 10 is false, so the program executes the else block and prints: "5 is less than 10."

**Example 2: Checking Equality

Here we use an if-else statement in R to check whether a number is equal to 10 or not.

R `

x <- 5

Check if value is equal to 10

if(x == 10) { print(paste(x, "is equal to 10")) } else { print(paste(x, "is not equal to 10")) }

`

**Output:

[1] "5 is not equal to 10"

Here x is 5, the condition x == 10 is false, so the else block runs and prints: "5 is not equal to 10."

Nested if-else Statements in R

The if-else statements in R can be nested to form a group of statements that evaluate conditions one by one, starting from the outer condition to the inner ones. An if-else statement placed within another if-else statement in R is called a nested statement.

• Nested if-else statements allow sequential evaluation of multiple conditions.
• Execution stops at the first TRUE condition in the hierarchy.

**Syntax

if(condition1) {

# execute if condition1 is TRUE

if(condition2) {

# execute if both condition1 and condition2 are TRUE

}

} else {

# execute if condition1 is FALSE

}

Example 1: Nested if-else

Here nested if-else in R evaluates multiple conditions to find the range of x

R `

x <- 15 if (x < 10) { print("x is less than 10") } else {

if (x < 20) { print("x is between 10 and 20") } else { print("x is greater than or equal to 20") } }

`

**Output:

[1] "x is between 10 and 20"

• Outer if checks x < 10, which is FALSE.
• Flow enters the else block and evaluates the nested if (x < 20), which is TRUE.
• The program prints "x is between 10 and 20".

Example 2: Nested if-else for Eligibility

In this R code we uses nested if-else statements to assess whether a student qualifies for a scholarship based on grades and income

R `

grades <- 85 income <- 25000

if (grades >= 80) { if (income <= 30000) { print("Congratulations, you are eligible for a scholarship!") } else { print("Sorry, your income is too high to qualify for a scholarship.") } } else { print("Sorry, your grades are too low to qualify for a scholarship.") }

`

**Output:

[1] "Congratulations, you are eligible for a scholarship!"

• Define grades and income to represent a student’s scores and financial status.
• Use a nested if-else to check scholarship eligibility based on grades and income.
• Outer if checks if grades ≥ 80; inner if checks if income ≤ 30,000.

Conditions and If Statements

Here we will show the use of logical conditions in if statements. Adjust the values and conditions as needed for our specific requirements.