validate_no_formula_duplication: Ensure no duplicate terms appear in 'formula'

View source: R/validation.R

validate_no_formula_duplicationR Documentation

Ensure no duplicate terms appear in formula


validate - asserts the following:

  • formula must not have duplicates terms on the left and right hand side of the formula.

check - returns the following:

  • ok A logical. Does the check pass?

  • duplicates A character vector. The duplicate terms.


validate_no_formula_duplication(formula, original = FALSE)

check_no_formula_duplication(formula, original = FALSE)



A formula to check.


A logical. Should the original names be checked, or should the names after processing be used? If FALSE, y ~ log(y) is allowed because the names are "y" and "log(y)", if TRUE, y ~ log(y) is not allowed because the original names are both "y".


validate_no_formula_duplication() returns formula invisibly.

check_no_formula_duplication() returns a named list of two components, ok and duplicates.


hardhat provides validation functions at two levels.

  • ⁠check_*()⁠: check a condition, and return a list. The list always contains at least one element, ok, a logical that specifies if the check passed. Each check also has check specific elements in the returned list that can be used to construct meaningful error messages.

  • ⁠validate_*()⁠: check a condition, and error if it does not pass. These functions call their corresponding check function, and then provide a default error message. If you, as a developer, want a different error message, then call the ⁠check_*()⁠ function yourself, and provide your own validation function.

See Also

Other validation functions: validate_column_names(), validate_outcomes_are_binary(), validate_outcomes_are_factors(), validate_outcomes_are_numeric(), validate_outcomes_are_univariate(), validate_prediction_size(), validate_predictors_are_numeric()


# All good
check_no_formula_duplication(y ~ x)

# Not good!
check_no_formula_duplication(y ~ y)

# This is generally okay
check_no_formula_duplication(y ~ log(y))

# But you can be more strict
check_no_formula_duplication(y ~ log(y), original = TRUE)

# This would throw an error
try(validate_no_formula_duplication(log(y) ~ log(y)))

hardhat documentation built on March 31, 2023, 10:21 p.m.