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

Answer 1

The reason you are getting this error is that you have a vector.

If you want to use the $ operator, you simply need to convert it to a data.frame. But since you only have one row in this particular case, you would also need to transpose it; otherwise bob and ed will become your row names instead of your column names which is what I think you want.

x <- c(1, 2)
x
names(x) <- c("bob", "ed")
x <- as.data.frame(t(x))
x$ed
[1] 2

Answer 2

Because $ does not work on atomic vectors. Use [ or [[ instead. From the help file for $:

The default methods work somewhat differently for atomic vectors, matrices/arrays and for recursive (list-like, see is.recursive) objects. $ is only valid for recursive objects, and is only discussed in the section below on recursive objects.

x[["ed"]] will work.

Answer 3

Here x is a vector. You need to convert it into a dataframe for using $ operator.

 x <- as.data.frame(x) 

will work for you.

x<-c(1,2)
names(x)<- c("bob","ed")
x <- as.data.frame(x)

will give you output of x as:
bob 1
ed 2
And, will give you output of x$ed as:
NULL
If you want bob and ed as column names then you need to transpose the dataframe like x <- as.data.frame(t(x)) So your code becomes

x<-c(1,2)
x
names(x)<- c("bob","ed")
x$ed
x <- as.data.frame(t(x))

Now the output of x$ed is:
[1] 2

Answer 4

Atomic collections are accessible by $

Recursive collections are not. Rather the [[ ]] is used

 Browse[1]> is.atomic(list())
 [1] FALSE

 Browse[1]> is.atomic(data.frame())
 [1] FALSE

 Browse[1]> is.atomic(class(list(foo="bar")))
 [1] TRUE

 Browse[1]> is.atomic(c(" lang "))
 [1] TRUE

R can be funny sometimes

 a = list(1,2,3)
 b = data.frame(a)
 d = rbind("?",c(b))
 e = exp(1)
 f = list(d)
 print(data.frame(c(list(f,e))))

   X1 X2 X3 X2.71828182845905
 1  ?  ?  ?          2.718282
 2  1  2  3          2.718282

Answer 5

You get this error, despite everything being in line, because of a conflict caused by one of the packages that are currently loaded in your R environment.

So, to solve this issue, detach all the packages that are not needed from the R environment. For example, when I had the same issue, I did the following:

detach(package:neuralnet)

bottom line: detach all the libraries no longer needed for execution... and the problem will be solved.

Answer 6

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