#This code is GPL3 def calc_check_digit(value): """calculate check digit, they are the same for both UPCA and UPCE""" check_digit=0 odd_pos=True for char in str(value)[::-1]: if odd_pos: check_digit+=int(char)*3 else: check_digit+=int(char) odd_pos=not odd_pos #alternate check_digit=check_digit % 10 check_digit=10-check_digit check_digit=check_digit % 10 return check_digit def convert_UPCE_to_UPCA(upce_value): """Test value 04182635 -> 041800000265""" if len(upce_value)==6: middle_digits=upce_value #assume we're getting just middle 6 digits elif len(upce_value)==7: #truncate last digit, assume it is just check digit middle_digits=upce_value[:6] elif len(upce_value)==8: #truncate first and last digit, #assume first digit is number system digit #last digit is check digit middle_digits=upce_value[1:7] else: return False d1,d2,d3,d4,d5,d6=list(middle_digits) if d6 in ["0","1","2"]: mfrnum=d1+d2+d6+"00" itemnum="00"+d3+d4+d5 elif d6=="3": mfrnum=d1+d2+d3+"00" itemnum="000"+d4+d5 elif d6=="4": mfrnum=d1+d2+d3+d4+"0" itemnum="0000"+d5 else: mfrnum=d1+d2+d3+d4+d5 itemnum="0000"+d6 newmsg="0"+mfrnum+itemnum #calculate check digit, they are the same for both UPCA and UPCE check_digit=calc_check_digit(newmsg) return newmsg+str(check_digit) #Usage example print convert_UPCE_to_UPCA(UPCE)