Leer Understanding if, else, and else if | R Conditional Statements Tutorial

Vereisten

R Introduction

Conditional statements are a fundamental part of programming in R, allowing you to control the flow of your code based on certain conditions. By using conditional statements, you can make your programs respond differently depending on the data or situation, making your code more flexible and intelligent. In R, the most common way to implement decision-making is by using the if, else, and else if statements.

Definition

A conditional statement is a programming construct that allows code to be executed only if a specific condition is met. Conditional statements are essential for introducing logic and decision-making into your programs.


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number <- 5

if (number > 0) {
  print("The number is positive.")
}

In this code, the if statement checks whether the variable number is greater than zero. The syntax starts with the if keyword, followed by a condition in parentheses. If this condition is TRUE, the code inside the curly braces is executed. In this case, since number is 5, R prints "The number is positive."


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number <- -3

if (number > 0) {
  print("The number is positive.")
} else {
  print("The number is negative.")
}

This example introduces the else keyword. If the condition in the if statement is FALSE, R executes the code block under else. Here, because number is -3, the first condition fails, so R prints "The number is negative." The else statement ensures that one of the two blocks will run, depending on the value of number.


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number <- 0

if (number > 0) {
  print("The number is positive.")
} else if (number < 0) {
  print("The number is negative.")
} else {
  print("The number is zero.")
}

By chaining conditions with else if, you can check multiple possible cases in order. R evaluates each condition one by one from top to bottom. As soon as it finds a TRUE condition, it executes the corresponding code block and ignores the rest. In this example:

If number is greater than zero, it prints "The number is positive.";
If not, but number is less than zero, it prints "The number is negative.";
If neither condition is true, the final else block runs, printing "The number is zero.".

This approach helps you control exactly which block of code runs based on the value of your variable.

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