Package 'assertthat'

Are two objects equal?

Description

Are two objects equal?

Usage

are_equal(x, y, ...)

Arguments

x, y	objects to compare
...	additional arguments passed to all.equal

See Also

Other assertions: is.error, is.scalar, noNA, not_empty

Examples

x <- 2
see_if(are_equal(x, 1.9))
see_if(are_equal(x, 1.999, tol = 0.01))
see_if(are_equal(x, 2))

---

Assert that certain conditions are true.

Description

assert_that is a drop-in replacement for stopifnot but is designed to give informative error messages.

Usage

assert_that(..., env = parent.frame(), msg = NULL)

see_if(..., env = parent.frame(), msg = NULL)

Arguments

...	unnamed expressions that describe the conditions to be tested. Rather than combining expressions with &&, separate them by commas so that better error messages can be generated.
env	(advanced use only) the environment in which to evaluate the assertions.
msg	a custom error message to be printed if one of the conditions is false.

Assertions

Assertion functions should return a single TRUE or FALSE: any other result is an error, and assert_that will complain about it. This will always be the case for the assertions provided by assertthat, but you may need be a more careful for base R functions.

To make your own assertions that work with assert_that, see the help for on_failure. Alternatively, a custom message can be specified for each call.

See Also

validate_that, which returns a message (not an error) if the condition is false.

Examples

x <- 1
# assert_that() generates errors, so can't be usefully run in
# examples
## Not run: 
assert_that(is.character(x))
assert_that(length(x) == 3)
assert_that(is.dir("asdf"))
y <- tempfile()
writeLines("", y)
assert_that(is.dir(y))
assert_that(FALSE, msg = "Custom error message")

## End(Not run)

# But see_if just returns the values, so you'll see that a lot
# in the examples: but remember to use assert_that in your code.
see_if(is.character(x))
see_if(length(x) == 3)
see_if(is.dir(17))
see_if(is.dir("asdf"))
see_if(5 < 3, msg = "Five is not smaller than three")

---

Missing is functions.

Description

Missing is functions.

Usage

is.error(x)

is.time(x)

is.date(x)

Arguments

x	object to test

See Also

Other assertions: are_equal, is.scalar, noNA, not_empty

Examples

a <- Sys.time()
is.time(a)
b <- Sys.Date()
is.date(b)
c <- try(stop("!!"))
is.error(c)

---

Useful test related to files

Description

Useful test related to files

Usage

is.dir(path)

is.writeable(path)

is.readable(path)

has_extension(path, ext)

Arguments

path	a file path to examine
ext	extension to test for (has_extension only)

Examples

see_if(is.dir(1))

tmp <- tempfile()
see_if(file.exists(tmp))
see_if(is.dir(tmp))

writeLines("x", tmp)
see_if(file.exists(tmp))
see_if(is.dir(tmp))
see_if(is.writeable(tmp))
see_if(is.readable(tmp))
unlink(tmp)

see_if(is.readable(tmp))

---

Check a function has specified arguments

Description

Check a function has specified arguments

Usage

has_args(f, args, exact = FALSE)

f %has_args% args

Arguments

f	a function
args	a character vector of argument names
exact	if TRUE, argument names must match args exactly (order and value); otherwise f just must have at least args in any order

Examples

has_args(mean, "x")
has_args(mean, "x", exact = TRUE)

see_if(mean %has_args% "x")
see_if(mean %has_args% "y")

---

Has attribute or name?

Description

Has attribute or name?

Usage

has_attr(x, which)

x %has_attr% which

has_name(x, which)

x %has_name% which

Arguments

x	object to test
which	name or attribute

Examples

has_attr(has_attr, "fail")
x <- 10
x %has_attr% "a"

y <- list(a = 1, b = 2)
see_if(y %has_name% "c")

---

Does object contain any missing values?

Description

Does object contain any missing values?

Usage

noNA(x)

Arguments

x	object to test

See Also

Other assertions: are_equal, is.error, is.scalar, not_empty

Examples

see_if(noNA("a"))
see_if(noNA(c(TRUE, NA)))
x <- sample(c(1:10, NA), 100, rep = TRUE)
see_if(noNA(x))

---

Check an object doesn't have any empty dimensions

Description

Check an object doesn't have any empty dimensions

Usage

not_empty(x)

Arguments

x	object to test

See Also

Other assertions: are_equal, is.error, is.scalar, noNA

Examples

not_empty(numeric())
not_empty(mtcars[0, ])
not_empty(mtcars[, 0])

---

Custom failure messages for assertions.

Description

Custom failure messages for assertions.

Usage

on_failure(x)

on_failure(x) <- value

Arguments

x	a assertion function that returns TRUE if the assertion is met, FALSE otherwise.
value	a function with parameters call and env that returns a custom error message as a string.

Examples

is_odd <- function(x) {
  assert_that(is.numeric(x), length(x) == 1)
  x %% 2 == 1
}
see_if(is_odd(2))

on_failure(is_odd) <- function(call, env) {
  paste0(deparse(call$x), " is even")
}
see_if(is_odd(2))

---

Assert input is a scalar.

Description

is.scalar provides a generic method for checking input is a scalar. is.string, is.flag, is.number and is.count provide tests for specific types.

Usage

is.scalar(x)

is.string(x)

is.number(x)

is.flag(x)

is.count(x)

Arguments

x	object to test

See Also

Other assertions: are_equal, is.error, noNA, not_empty

Examples

# Generic check for scalars
see_if(is.scalar("a"))
see_if(is.scalar(1:10))

# string = scalar character vector
see_if(is.string(1:3))
see_if(is.string(c("a", "b")))
see_if(is.string("x"))

# number = scalar numeric/integer vector
see_if(is.number(1:3))
see_if(is.number(1.5))

# flag = scalar logical vector
see_if(is.flag(1:3))
see_if(is.flag("a"))
see_if(is.flag(c(FALSE, FALSE, TRUE)))
see_if(is.flag(FALSE))

# count = scalar positive integer
see_if(is.count("a"))
see_if(is.count(-1))
see_if(is.count(1:5))
see_if(is.count(1.5))
see_if(is.count(1))

---

Validate that certain conditions are true.

Description

validate_that is an alternative to the function assert_that, that returns a character vector. This makes them easier to use within S4 "validate" methods.

Usage

validate_that(..., env = parent.frame(), msg = NULL)

Arguments

...	unnamed expressions that describe the conditions to be tested. Rather than combining expressions with &&, separate them by commas so that better error messages can be generated.
env	(advanced use only) the environment in which to evaluate the assertions.
msg	a custom error message to be printed if one of the conditions is false.

Value

A character vector if the assertion is false, or TRUE if the assertion is true.

See Also

assert_that, which returns an error if the condition is false.

Examples

x <- 1
# assert_that() generates errors, so can't be usefully run in
# examples
validate_that(is.numeric(x))
validate_that(is.character(x))
validate_that(length(x) == 3)
validate_that(is.dir("asdf"))

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