$ operator is invalid for atomic vectors in R

$ operator is invalid for atomic vectors in R

The R error "$ operator is invalid for atomic vectors in R" occurs when you try to access an element of an atomic vector using the \$ operator. To solve this, use double brackets [[]], the getElement() function, or convert the vector to a data.frame and use $.

An atomic vector is a 1-dimensional data object created from the c() or vector() functions. $ cannot be used to access elements in atomic vectors. $ can only be used for recursive objects. Vectors are atomic objects.

The solution is to use double brackets [[]] or the getElement() function.

Here is an example of how the error occurs.

# 👇️ define the vector
example <- c(6, 3, 8, 6, 2)

# provide names
names(example) <- c('a', 'b', 'c', 'd', 'e')

# display vector
example

>> a b c d e
   6 3 8 6 2

# ⛔️ Error: $ operator is invalid for atomic vectors in R
# attempt to access value in 'c'
example$c

The error occurs because we cannot use the $ operator to access elements in atomic vectors. $ can only be used for recursive objects.

We can check the the vector is in fact atomic and not recursive.

# 🔎 check if the vector is atomic
is.atomic(example)

# 🔎 check if the vector is recursive
is.recursive(example)

>> FALSE

Use double brackets [[]]

To solve this, we can access the elements in a vector by their name using the [[]] notation.

# 👇️ define the vector
example <- c(6, 3, 8, 6, 2)

# provide names
names(example) <- c('a', 'b', 'c', 'd', 'e')

# access value for 'c' using double brackets
example[['c']]
>> 8

Use getElement()

Another method is to use the getElement() function.

# 👇️ define the vector
example <- c(6, 3, 8, 6, 2)

# provide names
names(example) <- c('a', 'b', 'c', 'd', 'e')

# access value for 'c' using double brackets
getElement(example, 'c')
>> 8

Convert vector to a data frame and use $

A third way is to convert the vector into a data frame, and use the $ operator to access the elements by name.

# 👇️ define the vector
example <- c(6, 3, 8, 6, 2)

# provide names
names(example) <- c('a', 'b', 'c', 'd', 'e')

# convert the vector to a data frame
data_example <- as.data.frame(t(example))

# display the data frame
data_example
>> a b c d e
   6 3 8 6 2

# access value for 'c' using $
data_example$c
>> 8

Conclusion

The R error "$ operator is invalid for atomic vectors in R" occurs when you try to access an element of an atomic vector using the \$ operator. To solve this, use double brackets [[]], the getElement() function, or convert the vector to a data.frame and use $.