Function returning multiple values in R

Question

Say I have a function

f <- function(){

  # do things

  return(list(zoo = x, vector = y, integer = z))
}

When I call this function using

result <- f()

Is there any way to call the return variables explicitly? Ie do I have to call it using

vara <- result$vara
varb <- result$varb
varc <- result$varc

Since if this function returns a lot of data types (whether it be data frames, zoo's, vectors, etc). The reason I dont want to bind into data frame is because not all variables are of the same length.

Answer 1

Use with or within

If the problem is just that you don't like typing result , then you can use with or within to access elements inside the list.

with(result, vara + varb * varc)

This is a good, standard way of doing things.

Use list2env

You could copy the variables from the list using list2env .

 list2env(result, parent.frame())

This is slightly risky because you have two copies of your variables which may introduce bugs. If you are including the code in a package, R CMD check will give you warnings about global variables.

Use attach

This is a really bad idea (don't do this).

attach is like a permanent version of with . If you

attach(result)

then you can access each element without the result$ prefix. But it will lead to many horrendous, obscure bugs in your code when an error gets thrown before you detach it, and then you attach it a second time and drown in a variable-scope-swamp.