Check Numeric Argument

Checks whether an argument is numeric, with some additional constraints if desired. arg_numeric() simply checks whether the argument is numeric. arg_number() checks whether the argument is a numeric scalar (i.e., a single number). arg_whole_numeric() and arg_whole_number() check whether the argument is a whole numeric vector or scalar, respectively. arg_counts() and arg_count() check whether the argument is a non-negative whole numeric vector or scalar, respectively.

Usage

arg_numeric(x, .arg = rlang::caller_arg(x), .msg = NULL, .call)

arg_number(x, .arg = rlang::caller_arg(x), .msg = NULL, .call)

arg_whole_numeric(x, .arg = rlang::caller_arg(x), .msg = NULL, .call)

arg_whole_number(x, .arg = rlang::caller_arg(x), .msg = NULL, .call)

arg_counts(x, .arg = rlang::caller_arg(x), .msg = NULL, .call)

arg_count(x, .arg = rlang::caller_arg(x), .msg = NULL, .call)

Arguments

x

the argument to be checked

.arg

the name of the argument supplied to x to appear in error messages. The default is to extract the argument's name using rlang::caller_arg(). Ignored if .msg is supplied.

.msg

an optional alternative message to display if an error is thrown instead of the default message.

.call

the execution environment of a currently running function, e.g. .call = rlang::current_env(). The corresponding function call is retrieved and mentioned in error messages as the source of the error. Passed to err(). Set to NULL to omit call information. The default is to search along the call stack for the first user-facing function in another package, if any.

Value

Returns NULL invisibly if an error is not thrown.

Details

A whole number is decided by testing whether the value is an integer (i.e., using is.integer()) or if abs(x - trunc(x)) < sqrt(.Machine$double.eps). This is the same tolerance used by all.equal() to compare values.

See also

is.integer(), rlang::is_integerish()

Examples

count <- 3
whole <- -4
num <- .943

try(arg_number(count))       # No error
try(arg_whole_number(count)) # No error
try(arg_count(count))        # No error

try(arg_number(whole))       # No error
try(arg_whole_number(whole)) # No error
try(arg_count(whole))        # Error: negatives not allowed
#> Error : `whole` must be a count (a non-negative whole number).

try(arg_number(num))       # No error
try(arg_whole_number(num)) # Error: not a whole number
#> Error : `num` must be a whole number.
try(arg_count(num))        # Error: not a count
#> Error : `num` must be a count (a non-negative whole number).

nums <- c(0, .5, 1)

try(arg_number(nums))  # Error: not a single number
#> Error : `nums` must be a single number.
try(arg_numeric(nums)) # No error
try(arg_counts(nums))  # Error: not counts
#> Error : `nums` must be a vector of counts (non-negative whole numeric values).