R: Check if an argument is a formula

checkFormula {checkmate} | R Documentation

## Check if an argument is a formula

### Description

Check if an argument is a formula

### Usage

    checkFormula(x, null.ok = FALSE)

    check_formula(x, null.ok = FALSE)

    assertFormula(x, null.ok = FALSE, .var.name = vname(x), add = NULL)

    assert_formula(x, null.ok = FALSE, .var.name = vname(x), add = NULL)

    testFormula(x, null.ok = FALSE)

    test_formula(x, null.ok = FALSE)

    expect_formula(x, null.ok = FALSE, info = NULL, label = vname(x))

### Arguments

`x` | [any] Object to check.
`null.ok` | [`logical(1)`] If set to `TRUE`, `x` may also be `NULL`. In this case only a type check of `x` is performed, all additional checks are disabled.
`.var.name` | [`character(1)`] Name of the checked object to print in assertions. Defaults to the heuristic implemented in `vname`.
`add` | [`AssertCollection`] Collection to store assertion messages. See `AssertCollection`.
`info` | [`character(1)`] Extra information to be included in the message for the testthat reporter. See `expect_that`.
`label` | [`character(1)`] Name of the checked object to print in messages. Defaults to the heuristic implemented in `vname`.

### Value

Depending on the function prefix: If the check is successful, the functions `assertFormula`/`assert_formula` return `x` invisibly, whereas `checkFormula`/`check_formula` and `testFormula`/`test_formula` return `TRUE`. If the check is not successful, `assertFormula`/`assert_formula` throws an error message, `testFormula`/`test_formula` returns `FALSE`, and `checkFormula`/`check_formula` return a string with the error message. The function `expect_formula` always returns an `expectation`.

### See Also

Other basetypes: `checkArray()`, `checkAtomicVector()`, `checkAtomic()`, `checkCharacter()`, `checkComplex()`, `checkDataFrame()`, `checkDate()`, `checkDouble()`, `checkEnvironment()`, `checkFactor()`, `checkFunction()`, `checkIntegerish()`, `checkInteger()`, `checkList()`, `checkLogical()`, `checkMatrix()`, `checkNull()`, `checkNumeric()`, `checkPOSIXct()`, `checkRaw()`, `checkVector()`

### Examples

    f = Species ~ Sepal.Length + Sepal.Width
    checkFormula(f)

[Package checkmate version 2.1.0 Index]