How to Solve R Error in n(): Must be used inside dplyr verbs

This error occurs when you try to call the n() function from the dplyr package but already have plyr loaded after loading dplyr. Both packages have the functions summarise() or summarize() which use n().

You can solve the error by using the “package::function” syntax.

This tutorial will go through how to solve the error with code examples.

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Example

Let’s look at an example of using the n() function. The n() function is implemented specifically for each data source. We can only use the function within summarize(), mutate(), and filter().

library(dplyr)
library(plyr)

mtcars %>%

    group_by(cyl) %>%
    
summarize(count = n())

Let’s run the code to see what happens:

Error in `n()`:
! Must be used inside dplyr verbs.
Run `rlang::last_error()` to see where the error occurred.

The error occurs because we attempted to use the summarize() function from dplyr to count the number of entries under each cyl group. However, we loaded the plyr package after the dplyr package, which causes a conflict as both packages have the summarize function.

Solution

We can solve the error by using the “package::function” syntax, in this case dplyr::summarize. Using this syntax ensures that R knows exactly from which package to import the summarize() function. Let’s look at the revised code:

library(dplyr)
library(plyr)

mtcars %>%

    group_by(cyl) %>%

    dplyr::summarize(count = n())

Let’s run the code to get the result:

# A tibble: 3 × 2
    cyl count
  <dbl> <int>
1     4    11
2     6     7
3     8    14

Summary

Congratulations on reading to the end of this tutorial!

For further reading on R related errors, go to the article:

• How to Solve R Error: non-conformable arguments
• How to Solve R Error: not defined because of singularities

Go to the online courses page on R to learn more about coding in R for data science and machine learning.

Have fun and happy researching!