What are the Loops in the R language?

In this article, you will understand:

• What is a loop?
• Why do programmers use a loop?
• What are the different types of loops in the R Language?
• Brief introduction of each loop. 

Loops:

The loops are the set of statements that executes multiple times. It is a programming logic in the R programming language which executes the statement in continuation till the number of elements in the object.

Why do programmers use a loop?

Earlier, when the concept of loops does not exist, the programmer writes a few statements repeatedly for execution. So, to avoid the repetition of code statements, a programmer brought the concept of a loop. The advantage of using loops are:

• It decreases the length of code upto some extent.
• It saves the time of the programmer.

There are three loops in the R programming language:

• For Loop
• While Loop
• Repeat Loop

For Loop

For Loop is the entry-level loop. For Loop is useful in iterating the data elements whose data types are data frames, vectors, matrices, etc. 

Syntax of For loop

for (var in data frame) {

    statement(s)    

}

The loop is divided into three parts:

• initialization of the variable
• test condition statement
• increment and decrement action on the variable

After the variable initialization, if the test condition determines to be true, then the body written inside the loop executes. However, if the condition determines to be false, then the control comes out of the loop. Notably, it tests for the condition every time before the execution of the next iteration. 

While Loop

While Loop is an entry-controlled loop. Usually, while loop comes into existence, when the programmer is unaware of the number of iterations. It repeatedly executes the statements until they reach the stop condition. It returns the value in the boolean. The loop executes n+1 times instead of n times because it checks for the condition before entering the loop body. 

Syntax of While Loop

while (test_condition) {

   statement(s)

   update_expression

} 

It has a test condition in the first line, the body of the loop in the next line, and the expression updation in the last line. 

Repeat Loop

Repeat loop is used to execute the block of code multiple times. It will repeatedly execute the code until met with the break condition. It does not look for the condition to exit the loop. However, it searches for the break statement to come out of the loop. The break statement is defined in the if condition block. The programmer can conveniently create the infinite loop with the help of a Repeat loop. 

Syntax of Repeat Loop

repeat { 

   statement(s) 

   if(condition) {

      break

   }

}

The repeat keyword is used to define the repeat loop. It has statements, then an if condition block where the break statement is defined. The code executes until the if conditions turn out to be false.