libbib (version 1.6.4)

get_issn_check_digit: Get ISSN check digit

Description

Takes a string representation of an ISSN and returns the check digit that satisfies the necessary condition. It can take a 8 digit string (and ignore the already extant check digit) or a 7 digit string (without the last digit)

Usage

get_issn_check_digit(x, allow.hyphens = FALSE, errors.as.nas = FALSE)

Value

Returns the character check digit that satifies the mod 11 condition. Returns "X" if 10. Returns NA if input is NA

Arguments

x

A string of 7 or 8 digits

allow.hyphens

A logical indicating whether the hyphen separator should be allowed (default is FALSE)

errors.as.nas

return NA if error instead of throwing error (default is FALSE)

Examples

get_issn_check_digit("03785955")

get_issn_check_digit("2434-561X", allow.hyphens=TRUE)

# nine digit string
get_issn_check_digit("0378595")

# vectorized
get_issn_check_digit(c("0378595", "2434561X", NA))