Error with using enquo for creating function with ddplyr

Question

enter image description here

I have the data above, i want to aggregate some variables on the basis of mean of SalesInThousand Variable.

I am creating a function

Answer 1

The function arguments should match the ones inside the function i.e. if the argument of the data is 'df', it should be the same inside the function as well

testFunction <- function(df , x) {
 x <- enquo(x)
 df %>%
   group_by(!! x) %>%
   summarize(mean.Petal.Width = mean(Petal.Width))
}

testFunction(iris, Species)
# A tibble: 3 x 2
#    Species mean.Petal.Width
#      <fctr>            <dbl>
#1     setosa            0.246
#2 versicolor            1.326
#3  virginica            2.026

---

If we need to aggregate multiple variables, then use the summarise_at or summarise_all

testFunction <- function(df , varS, x) {
 x <- enquo(x)
 df %>%
   group_by(!! x) %>%
   summarize_at(vars(varS), funs(mean = mean(.)))
}

nm1 <- names(iris)[1:3]
testFunction(iris, nm1, Species)
# A tibble: 3 x 4
#     Species Sepal.Length_mean Sepal.Width_mean Petal.Length_mean
#      <fctr>             <dbl>            <dbl>             <dbl>
#1     setosa             5.006            3.428             1.462
#2 versicolor             5.936            2.770             4.260
#3  virginica             6.588            2.974             5.552