testing some barcode check digit validations

barcode-checks.py

# Library codabar (14 digit barcode) check digit validator
# (1 digit):material type + (4 digits):library code + (8 digits):item code + (1 digit): checksum
# source: http://www.makebarcode.com/specs/codabar.html
# - GOOD!
def vcodabar(n):
    """Validate the checkdigit of a 14 digit library barcode."""
    check = int(n[-1])
    data = n[:-1]
    total = 0
    for i, c in enumerate(data):
        c = int(c)
        total += c if (i % 2) else (2 * c - 9) if (2 * c > 9) else 2 * c
    calc = total % 10
    calc = 10 - calc if calc else 0
    print(calc)
    return calc == check



# source: http://www.makebarcode.com/specs/code_11.html
# possibly buggy / useless. Can't find a library barcode where this actually works.
# Suspect that maybe the checkdigit is only used in barcode scanning and isn't part
# of the code stored in MARC records?
# ??? likely wrong, at least no good with the data I'm looking at
def vcode11(n):
    check = int(n[-1])
    data = n[:-1]
    total = 0
    for i, c in enumerate(data[::-1]):
        total += int(c) * (i + 1)
    calc = total % 11
    print(calc)
    return calc == check