The Art of R Programming

Vectorized Operations

Suppose we have a function f() that we wish to apply to all elements of a vector x. In many cases, we can accomplish this by simply calling f() on x itself. This can really simplify our code and, moreover, give us a dramatic performance increase of hundredsfold or more.

One of the most effective ways to achieve speed in R code is to use operations that are vectorized, meaning that a function applied to a vector is actually applied individually to each element.

Vector In, Vector Out

You saw examples of vectorized functions earlier in the chapter, with the + and * operators. Another example is >.

> u <- c(5,2,8)
> v <- c(1,3,9)
> u > v
[1]  TRUE FALSE FALSE

Here, the > function was applied to u[1] and v[1], resulting in TRUE