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R – while loop

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While loop in R programming language is used when the exact number of iterations of a loop is not known beforehand. It executes the same code again and again until a stop condition is met. While loop checks for the condition to be true or false n+1 times rather than n times. This is because the while loop checks for the condition before entering the body of the loop.

R- While loop Syntax: 

while (test_expression) {
   statement
   update_expression
}  

While-loop-in-R

How does a While loop execute?  

  • Control falls into the while loop.
  • The flow jumps to Condition
  • Condition is tested. 
    • If the Condition yields true, the flow goes into the Body.
    • If the Condition yields false, the flow goes outside the loop
  • The statements inside the body of the loop get executed.
  • Updation takes place.
  • Control flows back to Step 2.
  • The while loop has ended and the flow has gone outside.

Important Points about while loop in R language:  

  • It seems to be that while the loop will run forever but it is not true, condition is provided to stop it.
  • When the condition is tested and the result is false then the loop is terminated.
  • And when the tested result is True, then the loop will continue its execution.

R – while loop Flowchart: 

R - while loopGeeksforgeeks

R – while loop

While Loop in R Programming Examples

Example 1: 

R

# R program to illustrate while loop
 
result <- c("Hello World")
i <- 1
 
# test expression
while (i < 6) {
 
   print(result)
    
   # update expression
   i = i + 1
}

                    

Output: 

[1] "Hello World"
[1] "Hello World"
[1] "Hello World"
[1] "Hello World"
[1] "Hello World"

Example 2:  

R

# R program to illustrate while loop
 
result <- 1
i <- 1
 
# test expression
while (i < 6) {
 
   print(result)
    
   # update expression
   i = i + 1
   result = result + 1
}

                    

Output: 

[1] 1
[1] 2
[1] 3
[1] 4
[1] 5

R – while loop break

Here we will use the break statement in the R programming language. The break statement in R is used to bring the control out of the loop when some external condition is triggered.

R

# R program to illustrate while loop
 
result <- c("Hello World")
i <- 1
 
# test expression
while (i < 6) {
 
    print(result)
     
    if( i == 3){
        break}
    # update expression
    i = i + 1
}

                    

Output:

[1] "Hello World"
[1] "Hello World"
[1] "Hello World"

R – while loop next

R

# Set an initial value for a variable
x <- 1
 
# Loop while x is less than 10
while (x < 10) {
  if (x == 3) {
    # Skip iteration when x is 3
    x <- x + 1
    next
  }
  print(paste("The current value of x is:", x))
  x <- x + 1
}
 
# Print a message after the loop has finished
print("The loop has ended.")

                    

Output

[1] "The current value of x is: 1"
[1] "The current value of x is: 2"
[1] "The current value of x is: 4"
[1] "The current value of x is: 5"
[1] "The current value of x is: 6"
[1] "The current value of x is: 7"
[1] "The current value of x is: 8"
[1] "The current value of x is: 9"

In this instance, x’s initial value is set to 1 at the beginning. Then, as long as x is less than 10, we continue iterating using a while-loop. We use an if statement inside the loop to see if x equals 3. If so, the loop’s current iteration is skipped in favor of the following one using the next statement. If not, we use the x – x + 1 expression to increment x by 1 and output a message stating the current value of x.

The next line instructs R to move on to the next iteration of the loop and skip the current one. based on a condition, over a subset of the loop’s iterations without ever leaving the loop.

 R While Loop with If .. Else

R

x <- 1
 
while (x <= 10) {
  if (x %% 2 == 0) {
    print(paste(x, "is even"))
  } else {
    print(paste(x, "is odd"))
  }
  x <- x + 1
}

                    

Output

[1] "1 is odd"
[1] "2 is even"
[1] "3 is odd"
[1] "4 is even"
[1] "5 is odd"
[1] "6 is even"
[1] "7 is odd"
[1] "8 is even"
[1] "9 is odd"
[1] "10 is even"

In this illustration, we initialize a variable x to 1, and then we iterate through the integers 1 through 10 using a while loop. We utilize an if-else statement inside the loop to determine whether x is even or odd. We publish a message stating that x is even if it is. We print a message noting that x is unusual if it is. Then, until x is more than 10, we increase x by 1 and loop till x is greater than 10.
 



Last Updated : 10 May, 2023
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