Calculate Control Character for Personal Identity Code

Calculate a valid control character for an incomplete Finnish personal identity codes (hetu).

Usage

hetu_control_char(pin, with.century = TRUE)

Arguments

pin: An incomplete PIN that ONLY has a date, century marker (optional, see parameter with.century) and personal number
with.century: If TRUE (default), the function assumes that the PIN input contains a century marker (DDMMYYQZZZ). If FALSE, the function assumes that the PIN contains only date and personal number (DDMMYYZZZ).

Value

Control character, either a number 0-9 or a letter.

Details

This method of calculating the control character was devised by mathematician Erkki Pale (1962) to detect input errors but also to detect errors produced by early punch card machines. The long number produced by writing the birth date and the personal number together are divided by 31 and the remainder is used to look up the control character from a separate table containing alphanumeric characters except letters G, I, O, Q and Z.

The method of calculating the control character does not need century character and therefore the function has an option to omit it.

Author

Pyry Kantanen

Examples

hetu_control_char("010101-010")
#> [1] "1"
hetu_control_char("010101010", with.century = FALSE)
#> [1] "1"