Control Structure Loops in R

Good Basic Reference: https://rpubs.com/mrandrewandrade/r_programming_basics_reference_sheet

We will learn about control structures loops used in R. Control strcutures in R contains conditionals, loop statements like any other programming languages.

Loops are very important and forms backbone to any programming languages.

If else statement:

#See the code syntax below for if else statement 
x=10
if(x>1){
 print("x is greater than 1")
 }else{
  print("x is less than 1")
  } 

## [1] "x is greater than 1"

#See the code below for nested if else statement
x=10
if(x>1 & x<7){
print("x is between 1 and 7")}else if(x>8 & x< 15){
    print("x is between 8 and 15")
}

## [1] "x is between 8 and 15"

For loops:

As we know for loops are used for iterating items

 #Below code shows for  loop implementation
x = c(1,2,3,4,5)
 for(i in 1:5){
     print(x[i])
 }

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

While loop:

#Below code shows while loop in R
x = 2.987
while(x <= 4.987) { 
     x = x + 0.987
     print(c(x,x-2,x-1)) 
}

## [1] 3.974 1.974 2.974
## [1] 4.961 2.961 3.961
## [1] 5.948 3.948 4.948

Repeat Loop

The repeat loop is an infinite loop and used in association with a break statement.

#Below code shows repeat loop:
a = 1
repeat{
     print(a)
     a = a+1 
     if(a > 4)break}

## [1] 1
## [1] 2
## [1] 3
## [1] 4

Break statement:

A break statement is used in a loop to stop the iterations and flow the control outside of the loop.

 #Below code shows break statement:
x = 1:10 
 for (i in x){ 
     if (i == 2){ 
         break 
     }
     print(i)
 }

## [1] 1

Next statement:

Next statement enables to skip the current iteration of a loop without terminating it.

 #Below code shows next statement 
x = 1: 4 
 for (i in x) { 
     if (i == 2){ 
         next}
     print(i)
 }

## [1] 1
## [1] 3
## [1] 4