DIZtools (version 1.0.3)

calculate_check_digit: Calculate Check Digit Using DIN/ISO 7064, Mod 11,10

Description

This function calculates the check digit for a given ID based on the DIN ISO 7064, Mod 11,10 algorithm.

Usage

calculate_check_digit(patid)

Value

An integer representing the computed check digit (0-9). Returns `NA` if the input is invalid.

Arguments

patid

A numeric or character string representing the ID. It should be either 9 or 10 digits long.

Details

The function processes the input `patid` as follows: - If the input has 10 digits and does not start with `0`, it is assumed to be a patient ID with a check digit. The check digit is removed. - If the input has 9 digits, a leading `0` is added. - If the input has 10 digits and starts with `0`, it is already in the expected format. - If the input does not match these cases, an error message is returned.

The check digit is calculated using the ISO 7064, Mod 11,10 method.

Examples

calculate_check_digit("100000138")  # Returns check digit (1) for this ID
calculate_check_digit(123456789)    # Works with numeric input as well (6)