We use the R repeat loop to execute a code block multiple times. However, the repeat loop doesn't have any condition to terminate the lYou can use the repeat loop in R to execute a block of code multiple times. However, the repeat loop does not have any condition to terminate the loop. You need to put an exit condition implicitly with a break statement inside the loop.
The syntax of repeat loop is:
repeat {
# statements
if(stop_condition) {
break
}
}
Here, we have used the repeat keyword to create a repeat loop. It is different from the for and while loop because it does not use a predefined condition to exit from the loop.
Example 1: R repeat Loop
Let's see an example that will print numbers using a repeat loop and will execute until the break statement is executed.
x = 1
# Repeat loop
repeat {
print(x)
# Break statement to terminate if x > 4
if (x > 4) {
break
}
# Increment x by 1
x = x + 1
}
Output
[1] 1 [1] 2 [1] 3 [1] 4 [1] 5
Here, we have used a repeat loop to print numbers from 1 to 5. We have used an if statement to provide a breaking condition which breaks the loop if the value of x is greater than 4.
Example 2: Infinite repeat Loop
If you fail to put a break statement inside a repeat loop, it will lead to an infinite loop. For example,
x = 1
sum = 0
# Repeat loop
repeat {
# Calculate sum
sum = sum + x
# Print sum
print(sum)
# Increment x by 1
x = x + 1
}
Output
[1] 1 [1] 3 [1] 6 [1] 10 . . .
In the above program, since we have not included any break statement with an exit condition, the program prints the sum of numbers infinitely.
Example 3: repeat Loop with next Statement
You can also use a next statement inside a repeat loop to skip an iteration. For example,
x = 1
repeat {
# Break if x = 4
if ( x == 4) {
break
}
# Skip if x == 2
if ( x == 2 ) {
# Increment x by 1 and skip
x = x + 1
next
}
# Print x and increment x by 1
print(x)
x = x + 1
}
Output
[1] 1 [1] 3
Here, we have a repeat loop where we break the loop if x is equal to 4. We skip the iteration where x becomes equal to 2.