*56*

One common error you may encounter in R is:

$ operator is invalid for atomic vectors

This error occurs when you attempt to access an element of an atomic vector using the **$** operator.

An “atomic vector” is any one-dimensional data object created by using the **c()** or **vector()** functions in R.

Unfortunately, the **$** cannot be used to access elements in atomic vectors. Instead, you must use double brackets **[[]]** or the **getElement()** function.

This tutorial shares examples of how to deal with this error in practice.

**How to Reproduce the Error Message**

Suppose we attempt to use the **$** operator to access an element in the following vector in R:

#define vector x #provide names names(x) #display vector x a b c d e 1 3 7 6 2 #attempt to access value in 'e' x$e Error in x$e : $ operator is invalid for atomic vectors

We receive an error because it’s not valid to use the **$** operator to access elements in atomic vectors. We can also verify that our vector is indeed atomic:

#check if vector is atomic is.atomic(x) [1] TRUE

**Method #1: Access Elements Using Double Brackets**

One way to access elements by name in a vector is to use the **[[]]** notation:

#define vector x #provide names names(x) #access value for 'e' x[['e']] [1] 2

**Method #2: Access Elements Using getElement()**

Another way to access elements by name in a vector is to use the **getElement()** notation:

#define vector x #provide names names(x) #access value for 'e' getElement(x, 'e') [1] 2

**Method #3 Convert Vector to Data Frame & Use $ Operator**

Yet another way to access elements by name in a vector is to first convert the vector to a data frame, then use the **$** operator to access the value:

#define vector x #provide names names(x) #convert vector to data frame data_x data.frame(t(x)) #display data frame data_x a b c d e 1 1 3 7 6 2 #access value for 'e' data_x$e [1] 2

**Additional Resources**

The following tutorials explain how to troubleshoot other common errors in R:

How to Fix in R: names do not match previous names

How to Fix in R: NAs Introduced by Coercion

How to Fix in R: Subscript out of bounds

How to Fix in R: contrasts can be applied only to factors with 2 or more levels