How many elements in a vector are greater than x without using a loop

Question

If I have the following vector :

x
[1]  1  5  8  9  1  0 15 15

and I want to know how many elements are greater than 10, how can I proceed without using a loop ?

I would like to get :

2

as a result

Answer 1

Use length or sum :

> length(x[x > 10])
[1] 2
> sum(x > 10)
[1] 2

In the first approach, you would be creating a vector that subsets the values that matches your condition, and then retrieving the length of the vector.

In the second approach, you are simply creating a logical vector that states whether each value matches the condition ( TRUE ) or doesn't ( FALSE ). Since TRUE and FALSE equate to "1" and "0", you can simply use sum to get your answer.

Because the first approach requires indexing and subsetting before counting, I am almost certain that the second approach would be faster than the first.

Answer 2

Another way to do this:

> length(which(as.vector(x) > 10))
[1] 2