How to define a vectorized function in R

Question

As the title, I\'d like to know how to define a vectorized function in R.

• Is it just by using a loop in the function?
• Is this method efficient?
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Answer 1

A vectorized function will return a vector of the same length as one of its arguments. Generally one can get such a function by using combinations of built-in functions like "+", cos or exp that are vectorized as well.

vecexpcos <- function(x) exp(cos(x))
vecexpcos( (1:10)*pi )
>    vecexpcos( (1:10)*pi )
# [1] 0.3678794 2.7182818 0.3678794 2.7182818 0.3678794 2.7182818 0.3678794 2.7182818 0.3678794 2.7182818

If you need to use a non-vectorized function like sum, you may need to invoke mapply or Vectorize in order to get the desired behavior.