Python Excel 列名轉換

def colname_to_num(colname):
    if type(colname) is not str:
        return colname

    col = 0
    power  = 1
    print len(colname)
    for i in xrange(len(colname) - 1, -1, -1):
        ch = colname[i]
        print ch
        col += (ord(ch) - ord('A') +  1 ) * power
        power *= 26
    print col-1
    return col - 1

def colnum_to_name(colnum):
    if type(colnum) != int:
        return colnum
    if colnum > 25:
        ch1 = chr(colnum % 26 + 65)
        ch2 = chr(colnum / 26 + 64)
        print ch2+ch1
        return ch2 + ch1
    else:
        print chr(colnum % 26 + 65)
        return chr(colnum % 26 + 65)

if __name__ == "__main__":
    colname_to_num("CU")
    colnum_to_name(26)