Table of Contents

In this R tutorial, we will take a look into for loops. At a very basic level, a loop will iterate over a sequence under set conditions that must be met. In other, words it can allow the automation of code that calls for repetition.

Vector is a basic data structure in R and contains elements of the same type. The vector data types can include logical, integer, double, character, complex or raw and can be checked with **typeof()** function. The length property of a vector is important as well and can be checked by using the **length()** function.

## for Loop Syntax

1 2 3 | for (val in sequence) { statement } |

The sequence is a vector and the val will take each value that’s iterated over the loop. With each iteration of the loop, the statement will be evaluated and meet the requirements.

**Input:**

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 | years <- c(2000,2001,2002,2003,2004,2005,2006,2007) count <- 0 for (year in years) { if(year %% 2 == 0) count = count+1 } print ('Vector Lengths') length(years) length(year) print('Vector Types') typeof(years) typeof(year) print(count) |

**Output:**

1 2 3 4 5 6 7 8 9 | [1] "Vector Lengths" [1] 8 [1] 1 [1] "Vector Types" [1] "double" [1] "double" [1] 4 |

In the above example, the loop iterates 8 times as the vector years has 8 elements. Within each iteration, year will take on the value of each element in year. The count variable will add 1 to each time a value meets the criteria if being divisible by 2.