R Conditionals

In R, conditionals help control the flow of a program. They evaluate Boolean expressions and execute certain blocks of code depending on whether the expression evaluates to TRUE or FALSE. This is especially useful while working with dynamic data, automating tasks, or writing functions with variable behavior.

R If Statement

The R if statement is used to run a block of code if a condition is TRUE.

Here is a flowchart that showcases the flow of the if statement in R:

R If Statement Syntax

if (condition) {
  # Code to execute if condition is TRUE
}

R If Statement Example

This example demonstrates the usage of the if statement in R:

x <- 10

if (x > 6) {
  print("x is greater than 6")
}

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Here is the output:

[1] "x is greater than 6"

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R If-Else Statement

The R if-else statement allows the execution of a block of code if a condition is TRUE, and a separate block of code if the condition is FALSE.

R If-Else Statement Syntax

if (condition) {
  # Code to execute if condition is TRUE
} else {
  # Code to execute if condition is FALSE
}

R If-Else Statement Example

This example demonstrates the usage of the if-else statement in R:

x <- 3

if (x > 6) {
  print("x is greater than 6")
} else {
  print("x is less than or equal to 6")
}

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Here is the output:

[1] "x is less than or equal to 6"

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R Else-If Statement

When there is a need to check multiple conditions, the R else-if statement can be used to evaluate them sequentially.

R Else-If Statement Syntax

if (condition1) {
  # Code if condition1 is TRUE
} else if (condition2) {
  # Code if condition2 is TRUE
} else {
  # Code if all conditions are FALSE
}

R Else-If Statement Example

This example demonstrates the usage of the else-if statement in R:

x <- 5

if (x > 12) {
  print("x is greater than 12")
} else if (x == 5) {
  print("x is equal to 5")
} else {
  print("x is less than 12 and not equal to 5")
}

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Here is the output:

[1] "x is equal to 5"

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Nested R If Statement

R if statements can be nested within each other for more complex logical checks.

Nested R If Statement Syntax

if (condition1) {
  if (condition2) {
    # Code to execute if both condition1 and condition2 are TRUE
  }
}

Nested R If Statement Example

This example demonstrates the usage of nested if statements in R:

x <- 8
y <- 3

if (x > 6) {
  if (y < 6) {
    print("x is greater than 6 and y is less than 6")
  }
}

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Here is the output:

[1] "x is greater than 6 and y is less than 6"

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Frequently Asked Questions

1. Can I use conditionals in a vectorized way in R?

Yes, you can use the R ifelse() function for vectorized operations:

x <- c(2, 5, 8)

result <- ifelse(x > 5, "High", "Low")

print(result) # Output: [1] "Low"  "Low"  "High"

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2. What’s the difference between R if and ifelse()?

• if statement in R is used for single, scalar conditions.
• ifelse() function in R is vectorized and works over entire vectors.

3. Can I use logical operators in R conditionals?

Yes. You can combine conditions using & (AND), | (OR), and ! (NOT):

x <- 4
if (x > 2 & x < 10) {
  print("x is between 2 and 10")
} # Output: [1] "x is between 2 and 10"

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4. What are the three elements of the if statement in R?

The three elements of an if statement in R are:

• Condition: A logical expression that evaluates to TRUE or FALSE.
• Code block for TRUE: The set of statements to execute if the condition is TRUE.
• Optional else block: A set of statements to run if the condition is FALSE.