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Check if an argument is a string

Source: R/checkString.R
checkString.Rd

A string is defined as a scalar character vector. To check for vectors of arbitrary length, see checkCharacter.

Usage

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

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

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

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

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

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

expect_string(
  x,
  na.ok = FALSE,
  n.chars = NULL,
  min.chars = NULL,
  max.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.

n.chars

[integer(1)]
Exact number of characters for each element of x.

min.chars

[integer(1)]
Minimum number of characters for each element of x.

max.chars

[integer(1)]
Maximum number of characters for each element of x.

pattern

[character(1L)]
Regular expression as used in grepl. All non-missing 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 non-missing 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.

Value

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

Details

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

See also

Other scalars: checkCount(), checkFlag(), checkInt(), checkNumber(), checkScalar(), checkScalarNA()

Examples

testString("a")
#> [1] TRUE
testString(letters)
#> [1] FALSE