Error Message in R: Function must only be used inside dplyr verbs (2 Examples)

In this R post you’ll learn how to handle the error message “must only be used inside dplyr verbs”.

Example Data

data(iris)                        # Example data
head(iris)
#   Sepal.Length Sepal.Width Petal.Length Petal.Width Species
# 1          5.1         3.5          1.4         0.2  setosa
# 2          4.9         3.0          1.4         0.2  setosa
# 3          4.7         3.2          1.3         0.2  setosa
# 4          4.6         3.1          1.5         0.2  setosa
# 5          5.0         3.6          1.4         0.2  setosa
# 6          5.4         3.9          1.7         0.4  setosa

Example 1: Replicating the Error Message: `n()` must only be used inside dplyr verbs.

install.packages("dplyr")         # Install & load dplyr
library("dplyr")
install.packages("plyr")          # Install plyr package
library("plyr")                   # Load plyr package
iris %>%                          # Code leads to error
  group_by(Species) %>% 
  summarize(freq = n())
# Error: `n()` must only be used inside dplyr verbs.

Example 2: Solving the Error Message: `n()` must only be used inside dplyr verbs.

iris %>%                          # Code leads to error
  group_by(Species) %>% 
  dplyr::summarize(freq = n())
   # # A tibble: 3 x 2
#   Species     freq
#   <fct>      <int>
# 1 setosa        50
# 2 versicolor    50
# 3 virginica     50

Further Resources

In addition, you could have a look at the related R programming tutorials of my homepage.

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