In R, what is the easiest way to scale a vector to a unit vector?

Question

In R, what is the easiest way to scale a vector to a unit vector?

For example, suppose that

>vec [1] 1 0 2 1 

and

 >vec / sqrt(sum(vec^2)) [1] 0.4082483 0.0000000 0.8164966 0.4082483 

is its unit vector.

Is there any built-in function in R?

Answer 1

You can make yourself a function:

 scalar1 <- function(x) {x / sqrt(sum(x^2))} 

Now just use:

 > scalar1(vec) [1] 0.4082483 0.0000000 0.8164966 0.4082483 

Answer 2

The ppls package contains the normalize.vector function, which does exactly what you want. However, downloading a package doesn’t seem much easier than entering a function line directly ...

The fact that the ppls package implements the function probably means that to achieve this goal there is no standard function R. (Unless, of course, the author of ppls simply did not know about the standard function ...)