Looping in R

LOOPS in R

Loops are part of iterative programming where the user wants to perform a sequence of instructions N number of times.

R provides 3 styles of loops:

1. For Loop
2. While Loop
3. Repeat Loop

For Loop

For loops are used when we want to iterate over a sequence like vectors and or data frames.

Syntax:

v<-c(10,21,11,31,88,78)

for(i in v){

      print(i)

}

This will iterate over all the elements of vector v.

For iterating over individual elements using the index one can use sequence vector and use it as index.

Syntax:

v<-c(10,21,11,31,88,78)

for(i in 1:length(v)){

      print(v[i])

}

While Loop

While loops are used when the iterations depend on a condition and it is difficult to predict the number of iterations.

SYNTAX:

i<-2
while(i<=10){
         print(i)
         i<-i+2
}

Repeat

Repeat is a new construct available only in R to run an infinite loop. Repeat block will iterate until a break statement is encountered.

SYNTAX:

i<-2

repeat{

     print(i)

     if(i>10){

            break

     }

}