A for loop is used to iterate over a vector in R programming.
Syntax of for loop
for (val in sequence)
{
statement
}
Here, sequence is a vector and val takes on each of
its value during the loop. In each iteration, statement is
evaluated.
Flowchart of for loop
Example: for loop
Below is an example to count the number of even numbers in a vector.
x <- c(2,5,3,9,8,11,6)
count <- 0
for (val in x) {
if(val %% 2 == 0) count = count+1
}
print(count)
Output
[1] 3
In the above example, the loop iterates 7 times as the vector
x has 7 elements.
In each iteration, val takes on the value of corresponding
element of x.
We have used a counter to count the number of even numbers in x.
We can see that x contains 3 even numbers.
Check out these examples to learn more about for loop: