R Error in x$ed : $ operator is invalid for atomic vectors

Question

Here is my code:

x<-c(1,2)
x
names(x)<- c("bob","ed")
x$ed

Why do I get the following error?

Error in x$ed : $ operator is invalid for atomic vectors

Answer 1

From the help file about $ (See ?"$") you can read:

$ is only valid for recursive objects, and is only discussed in the section below on recursive objects.

Now, let's check whether x is recursive

> is.recursive(x)
[1] FALSE

A recursive object has a list-like structure. A vector is not recursive, it is an atomic object instead, let's check

> is.atomic(x)
[1] TRUE

Therefore you get an error when applying $ to a vector (non-recursive object), use [ instead:

> x["ed"]
ed 
 2 

You can also use getElement

> getElement(x, "ed")
[1] 2