Functions takes a list of formulas, a named list, or a combination of named elements with formula elements and returns a named list. For example, list(age = 1, starts_with("stage") ~ 2).

  data = NULL,
  var_info = NULL,
  arg_name = NULL,
  select_single = FALSE,
  type_check = NULL,
  type_check_msg = NULL,
  null_allowed = TRUE



list of selecting formulas


A data frame to select columns from. Default is NULL


A data frame of variable names and attributes. May also pass a character vector of variable names. Default is NULL


Optional string indicating the source argument name. This helps in the error messaging. Default is NULL.


Logical indicating whether the result must be a single variable. Default is FALSE


A predicate function that checks the elements passed on the RHS of the formulas in x= (or the element in a named list) satisfy the function.


When the type_check= fails, the string provided here will be printed as the error message. When NULL, a generic error message will be printed.


Are NULL values accepted for the right hand side of formulas?


A shortcut for specifying an option be applied to all columns/variables is omitting the LHS of the formula. For example, list(~ 1) is equivalent to passing list(everything() ~ 1).

Additionally, a single formula may be passed instead of placing a single formula in a list; e.g. everything() ~ 1 is equivalent to passing list(everything() ~ 1)