Transform A,B,…AA,AB,.. to 1,2,..27,28,..

NOTE: Below code is Python 3.

base = 26
def transform(row):
    res = []
    for field in [tmp.strip() for tmp in row.split(',')]:
        ival = 0
        power = 0
        for c in field[::-1]:
            ival += pow(base,power)*(ord(c)-ord('A')+1)
            power += 1
        res.append(ival)
    return res


print(transform("A, B, Z, AA, AB, AAA"))

Output:

[1, 2, 26, 27, 28, 703]