Checks if a string is a syntactically and algorithmically valid CASRN

A valid CAS Registry Number (CASRN) is a string in the format "dd...d-dd-d", containing 5 to 10 digits in total. The final digit is a check-digit calculated using a specific algorithm. This function validates both the format and the check-digit calculation.

Usage

is_cas(x)

Arguments

x

A character vector of potential CASRN strings.

Value

A logical vector of the same length as x. Returns TRUE for each valid CASRN, FALSE for invalid ones, and NA for NA inputs.

Examples

is_cas("50-00-0")  # Valid
#> [1] TRUE
is_cas("50-00-1")  # Invalid check digit
#> [1] FALSE
is_cas("7732-18-5") # Valid
#> [1] TRUE
is_cas("100-42-5")  # Valid
#> [1] TRUE
is_cas("not-a-casrn")
#> [1] FALSE
is_cas(c("50-00-0", "50-00-1", NA, "7732-18-5"))
#> [1]  TRUE FALSE    NA  TRUE