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How to use the break statement in a for loop in R

Onyejiaku Theophilus Chidalu

Overview

A break statement in R is used to stop a loop from executing, even while the condition provided is True.

A for loop in R is used for iterating over a sequence for a specific number of times. The number of iterations or repetitions is determined or defined by a conditional statement, the expression, within the for loop.

To declare a for loop in R, take a good look at its syntax below:

for(expression){
  statement(s)
}

From the syntax shown above, we can see that the expression represents the given condition, while the statement represents what the code should execute if the expression is True.

The importance of the for loop is such that it is required when there is a need for a repetition of the same code, until a particular condition is met.

To better understand how the for loop works, let’s look at the examples given below:

Example

for (x in 1:5) {
  print(x)
}
Using a "for" loop to print values

Explanation

In the code given above, we stated a condition that for x having values ranging from 1 to 5 (these are the iterations), R should print all the values of x.

How to use the break statement

We can stop a for loop before it iterates through all the items provided in the condition, using the break statement.

In the example below, we are creating a list variable and, using the break statement, we will stop the iteration at a specified item in the list.

Example

countries <- list("USA", "FRANCE", "UK", "CANADA")

for (x in countries) {
  if (x == "CANADA"){
    break
  }
  print(x)
}
Using the "break" statement in a "for" loop

Explanation

From the code given above, the loop will stop at "CANADA", because we chose to finish the loop by using the break statement when x is equal to "CANADA" (x == "CANADA").

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Onyejiaku Theophilus Chidalu
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