# Conditionals

Anonymous contributor
Anonymous contributor
Published May 26, 2023
Contribute to Docs

Conditional statements in R allow the control of flow in programs based on certain conditions. Using these statements different blocks of code can be executed depending on whether a condition is true or false.

## If Statement

The `if` statement is used to execute a block of code if a condition is true. The general syntax is:

``````if (condition) {
# Code to be executed if condition is true
}
``````

## If-Else Statement

The `if-else` statement allows the execution of a block of code if a condition is true, and another block of code if the condition is false. The general syntax is:

``````if (condition) {
# Code to be executed if condition is true
} else {
# Code to be executed if condition is false
}
``````

Examples of `if-else` statements:

```# If Statementx <- 10
if (x > 5) {  print("x is greater than 5")}# In this example, the code inside the if block will be executed because the condition x > 5 is true.

# If-Else Statementx <- 3
if (x > 5) {  print("x is greater than 5")} else {  print("x is less than or equal to 5")}# In this example, since the condition x > 5 is false, the code inside the else block will be executed.
```

## Comparison Operators

Comparison operators in R allow the comparison of values and produce logical results. Here are some commonly used comparison operators:

• `<` (less than): Returns `TRUE` if the left operand is less than the right operand.
• `>` (greater than): Returns `TRUE` if the left operand is greater than the right operand.
• `==` (equal to): Returns `TRUE` if the left operand is equal to the right operand.
• `!=` (not equal to): Returns `TRUE` if the left operand is not equal to the right operand.
• `<=` (less than or equal to): Returns `TRUE` if the left operand is less than or equal to the right operand.
• `>=` (greater than or equal to): Returns `TRUE` if the left operand is greater than or equal to the right operand.

Examples of comparison operators in R:

```# Less than (<)x <- 5y <- 10
if (x < y) {  print("x is less than y")}# Output: x is less than y

# Greater than (>)x <- 5y <- 10
if (x > y) {  print("x is greater than y")}# No output in this case

# Equal to (==)x <- 5y <- 5
if (x == y) {  print("x is equal to y")}# Output: x is equal to y

# Not equal to (!=)x <- 5y <- 10
if (x != y) {  print("x is not equal to y")}# Output: x is not equal to y

# Less than or equal to (<=)x <- 5y <- 10
if (x <= y) {  print("x is less than or equal to y")}# Output: x is less than or equal to y

# Greater than or equal to (>=)x <- 5y <- 5
if (x >= y) {  print("x is greater than or equal to y")}# Output: x is greater than or equal to y
```

These operators are commonly used in conditional statements to compare values and make decisions.

## Logical Operators

Logical operators in R can be used to combine or negate logical values. Here are the commonly used logical operators:

• `&&` (and): Returns `TRUE` if both the left and right operands are `TRUE`.
• `||` (or): Returns `TRUE` if either the left or right operand is `TRUE`.
• `!` (not): Negates a logical value. If the operand is `TRUE`, it returns `FALSE`, and if the operand is `FALSE`, it returns `TRUE`.

Examples of logical operators in R:

```# AND (&&)x <- 5y <- 10
if (x > 0 && y > 0) {  print("Both x and y are positive")}# Output: Both x and y are positive

# OR (||)x <- 5y <- -10
if (x > 0 || y > 0) {  print("Either x or y is positive")}# Output: Either x or y is positive

# NOT (!)x <- 5
if (!(x == 10)) {  print("x is not equal to 10")}# Output: x is not equal to 10
```

Logical operators are often used to combine multiple conditions in conditional statements or to negate a condition.

These are the basic conditional statements, comparison operators, and logical operators in R. They can be leveraged to control the flow of a program, compare values, and make decisions based on specific conditions.