stdnum.damm

The Damm algorithm.

The Damm algorithm is a check digit algorithm that should detect all single-digit errors and all adjacent transposition errors. Based on anti-symmetric quasigroup of order 10 it uses a substitution table.

This implementation uses the table from Wikipedia by default but a custom table can be provided.

More information:

• https://en.wikipedia.org/wiki/Damm_algorithm

>>> validate('572')
Traceback (most recent call last):
    ...
InvalidChecksum: ...
>>> calc_check_digit('572')
'4'
>>> validate('5724')
'5724'

stdnum.damm.calc_check_digit(number, table=None)

With the provided number, calculate the extra digit that should be appended to make it pass the Damm check.

stdnum.damm.checksum(number, table=None)

Calculate the Damm checksum over the provided number. The checksum is returned as an integer value and should be 0 when valid.

stdnum.damm.is_valid(number, table=None)

Checks to see if the number provided passes the Damm algorithm.

stdnum.damm.validate(number, table=None)

Checks to see if the number provided passes the Damm algorithm.