Content # Dicts for Encoding first_dig_to_parity = { 0: "LLLLLLRRRRRR", 1: "LLGLGGRRRRRR", 2: "LLGGLGRRRRRR", 3: "LLGGGLRRRRRR", 4: "LGLLGGRRRRRR", 5: "LGGLLGRRRRRR", 6: "LGGGLLRRRRRR", 7: "LGLGLGRRRRRR", 8: "LGLGGLRRRRRR", 9: "LGGLGLRRRRRR" } dig_encoding = { 0: {'L': "0001101", 'G': "0100111", 'R': "1110010"}, 1: {'L': "0011001", 'G': "0110011", 'R': "1100110"}, 2: {'L': "0010011", 'G': "0011011", 'R': "1101100"}, 3: {'L': "0111101", 'G': "0100001", 'R': "1000010"}, 4: {'L': "0100011", 'G': "0011101", 'R': "1011100"}, 5: {'L': "0110001", 'G': "0111001", 'R': "1001110"}, 6: {'L': "0101111", 'G': "0000101", 'R': "1010000"}, 7: {'L': "0111011", 'G': "0010001", 'R': "1000100"}, 8: {'L': "0110111", 'G': "0001001", 'R': "1001000"}, 9: {'L': "0001011", 'G': "0010111", 'R': "1110100"} } def add_check_digit(digits): sum = 0 for i in range(0, 12, 2): sum += digits[i] + 3*digits[i+1] return digits+[(-sum)%10] def digits_to_code(digits): parity = first_dig_to_parity[digits[0]] code = [] for i in range(1, len(digits)): code += dig_encoding[digits[i]][parity[i-1]] return code