dplyr: assign a variable a tidy-select expression for reuse-CodePudding

let's say i have a lot of columns, but i usually do some calculations on a specific subset of columms

my_df <- mtcars %>%
    filter(if_all(contains("p"), is.numeric)) %>%
    mutate(across(contains("p"), as.character))

i want to assign that tidy-select to a variable so i can use it later on, something like:

# doesn't work
my_cols <- contains("p")
my_df <- mtcars %>%
    filter(if_all(my_cols, is.numeric)) %>%
    mutate(across(my_cols, as.character))

many thanks

CodePudding user response：

You can use vars_select for a tidyselect option:

my_cols <- tidyselect::vars_select(names(mtcars), contains("p"))

Otherwise, use grepl or str_detect:

names(mtcars)[str_detect(names(mtcars), "p")]
names(mtcars)[grepl("p", names(mtcars))]

CodePudding user response：

You could quote the tidy-select syntax and inject them with !! in the functions that support tidy selections.

my_cols <- quote(contains("Sepal"))

iris %>%
  filter(if_all(!!my_cols, `>`, 4))

  Sepal.Length Sepal.Width Petal.Length Petal.Width Species
1          5.7         4.4          1.5         0.4  setosa
2          5.2         4.1          1.5         0.1  setosa
3          5.5         4.2          1.4         0.2  setosa