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Last data update: 2014.03.03

R: Check if an argument is a string

checkString

R Documentation

Check if an argument is a string

Description

A string is defined as a scalar character vector.

Usage

checkString(x, na.ok = FALSE, min.chars = NULL, pattern = NULL,
  fixed = NULL, ignore.case = FALSE, null.ok = FALSE)

check_string(x, na.ok = FALSE, min.chars = NULL, pattern = NULL,
  fixed = NULL, ignore.case = FALSE, null.ok = FALSE)

assertString(x, na.ok = FALSE, min.chars = NULL, pattern = NULL,
  fixed = NULL, ignore.case = FALSE, null.ok = FALSE,
  .var.name = vname(x), add = NULL)

assert_string(x, na.ok = FALSE, min.chars = NULL, pattern = NULL,
  fixed = NULL, ignore.case = FALSE, null.ok = FALSE,
  .var.name = vname(x), add = NULL)

testString(x, na.ok = FALSE, min.chars = NULL, pattern = NULL,
  fixed = NULL, ignore.case = FALSE, null.ok = FALSE)

test_string(x, na.ok = FALSE, min.chars = NULL, pattern = NULL,
  fixed = NULL, ignore.case = FALSE, null.ok = FALSE)

expect_string(x, na.ok = FALSE, min.chars = NULL, pattern = NULL,
  fixed = NULL, ignore.case = FALSE, null.ok = FALSE, info = NULL,
  label = vname(x))

Arguments

`x`	[any] Object to check.
`na.ok`	[`logical(1)`] Are missing values allowed? Default is `FALSE`.
`min.chars`	[`integer(1)`] Minimum number of characters in each element of `x`.
`pattern`	[`character(1L)`] Regular expression as used in `grepl`. All elements of `x` must comply to this pattern.
`fixed`	[`character(1)`] Substring to detect in `x`. Will be used as `pattern` in `grepl` with option `fixed` set to `TRUE`. All elements of `x` must contain this substring.
`ignore.case`	[`logical(1)`] See `grepl`. Default is `FALSE`.
`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`.

Details

This function does not distinguish between NA, NA_integer_, NA_real_, NA_complex_ NA_character_ and NaN.

Value

Depending on the function prefix: If the check is successful, the functions return TRUE. If the check is not successful, assertString/assert_string throws an error message, testString/test_string returns FALSE, and checkString returns a string with the error message. The function expect_string always returns an expectation.

Examples

testString("a")
testString(letters)