Encode alphanumeric in QR code

encode_alphanumeric.py

'''
Encode alphanumeric in QR code
'''

def encode_alphanum(c):
    if c >= '0' and c <= '9':
        return ord(c) - ord('0')
    elif c >= 'A' and c <= 'Z':
        return ord(c) - ord('A') + 10
    elif c == ' ':
        return 36
    elif c == '$':
        return 37
    elif c == '%':
        return 38
    elif c == '*':
        return 39
    elif c == '+':
        return 40
    elif c == '-':
        return 41
    elif c == '.':
        return 42
    elif c == '/':
        return 43
    elif c == ':':
        return 44
    else:
        raise Exception('non alphanumeric character %s' % c)

data = 'WE LOVE KIMWIPE'
blocks = []
for a, b in zip(data[0::2], data[1::2]):
    blocks.append((a, b))
if len(data) % 2 != 0:
    blocks.append((None, data[-1]))

encoded_nums = []
for block in blocks:
    if block[0] == None:
        encoded_nums.append(
            encode_alphanum(block[1])
        )
    else:
        encoded_nums.append(
            encode_alphanum(block[0]) * 45 + encode_alphanum(block[1])
        )
print(encoded_nums)