6.0 Utility functions to verify variable properties

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Description

Utility functions to verify an objects's properties including whether it is a scalar or vector, the class, the length, and (if numeric) whether the range of values is on a specified interval. Additionally, the checkLengths function can be used to ensure that all the supplied inputs have equal lengths.

Usage

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isInteger(x)
checkScalar(x, isType = "numeric", ...)
checkVector(x, isType = "numeric", ..., length=NULL) 
checkRange(x, interval = 0:1, inclusion = c(TRUE, TRUE), 
   varname = deparse(substitute(x)), tol=0)
checkLengths(..., allowSingle=FALSE)

Arguments

x

any object.

isType

character string defining the class that the input object is expected to be.

length

integer specifying the expected length of the object in the case it is a vector. If length=NULL, the default, then no length check is performed.

interval

two-element numeric vector defining the interval over which the input object is expected to be contained. Use the inclusion argument to define the boundary behavior.

inclusion

two-element logical vector defining the boundary behavior of the specified interval. A TRUE value denotes inclusion of the corresponding boundary. For example, if interval=c(3,6) and inclusion=c(FALSE,TRUE), then all the values of the input object are verified to be on the interval (3,6].

varname

character string defining the name of the input variable as sent into the function by the caller. This is used primarily as a mechanism to specify the name of the variable being tested when checkRange is being called within a function.

tol

numeric scalar defining the tolerance to use in testing the intervals of the

checkRange function.

...

For the checkScalar and checkVector functions, this input represents additional arguments sent directly to the checkRange function. For the

checkLengths function, this input represents the arguments to check for equal lengths.

allowSingle

logical flag. If TRUE, arguments that are vectors comprised of a single element are not included in the comparative length test in the checkLengths function. Partial matching on the name of this argument is not performed so you must specify 'allowSingle' in its entirety in the call.

Details

isInteger is similar to is.integer except that isInteger(1) returns TRUE whereas is.integer(1) returns FALSE.

checkScalar is used to verify that the input object is a scalar as well as the other properties specified above.

checkVector is used to verify that the input object is an atomic vector as well as the other properties as defined above.

checkRange is used to check whether the numeric input object's values reside on the specified interval. If any of the values are outside the specified interval, a FALSE is returned.

checkLength is used to check whether all of the supplied inputs have equal lengths.

Examples

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# check whether input is an integer
isInteger(1)
isInteger(1:5)
try(isInteger("abc")) # expect error

# check whether input is an integer scalar
checkScalar(3, "integer")

# check whether input is an integer scalar that resides 
# on the interval on [3, 6]. Then test for interval (3, 6].
checkScalar(3, "integer", c(3,6))
try(checkScalar(3, "integer", c(3,6), c(FALSE, TRUE))) # expect error

# check whether the input is an atomic vector of class numeric,
# of length 3, and whose value all reside on the interval [1, 10)
x <- c(3, pi, exp(1))
checkVector(x, "numeric", c(1, 10), c(TRUE, FALSE), length=3)

# do the same but change the expected length; expect error
try(checkVector(x, "numeric", c(1, 10), c(TRUE, FALSE), length=2))

# create faux function to check input variable
foo <- function(moo) checkVector(moo, "character")
foo(letters)
try(foo(1:5)) # expect error with function and argument name in message

# check for equal lengths of various inputs
checkLengths(1:2, 2:3, 3:4)
try(checkLengths(1,2,3,4:5)) # expect error

# check for equal length inputs but ignore single element vectors
checkLengths(1,2,3,4:5,7:8, allowSingle=TRUE)

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