我如何使用 Python 处理新加坡车牌的校验和

Question

I have researched and searched internet on the checksum of Singapore Car License Plate. For the license plate of SBA 1234, I need to convert all the digits excluding the S to numbers. A being 1, B being 2, and so on. SBA 1234 is in a string in a text format. How do i convert B and A to numbers for the calculation for the checksum while making sure that the value B and A do not change. The conversion of B and A to numbers is only for the calculation. How do i do the conversion for this with Python. Please help out. Thank you.

Answer 1

There are multiple ways to create a dictionary with values A thru Z representing values 1 thru 26. One of the simple way to do it will be:

value = dict(zip("ABCDEFGHIJKLMNOPQRSTUVWXYZ", range(1,27)))

An alternate way to it would be using the ord() function.

ord('A') is 65. You can create a dictionary with values A thru Z representing values 1 thru 26. To do that, you can use simple code like this.

atoz = {chr(i): i - 64 for i in range(ord("A"), ord("A") + 26)}

This will provide an output with a dictionary

{'A': 1, 'B': 2, 'C': 3, 'D': 4, 'E': 5, 'F': 6, 'G': 7, 'H': 8, 'I': 9, 'J': 10, 'K': 11, 'L': 12, 'M': 13, 'N': 14, 'O': 15, 'P': 16, 'Q': 17, 'R': 18, 'S': 19, 'T': 20, 'U': 21, 'V': 22, 'W': 23, 'X': 24, 'Y': 25, 'Z': 26}

You can search for the char in the dictionary to get 1 thru 26.

Alternate, you can directly use ord(x) - 64 to get a value of the alphabet. If x is A, you will get 1. Similarly, if x is Z, the value will be 26.

So you can write the code directly to calculate the value of the Singapore Number Plate as:

snp = 'SBA 1234'

then you can get a value of

snp_num = [ord(snp[1]) - 64,ord(snp[2]) - 64, int(snp[4]), int(snp[5]), int(snp[6])]

This will result in

[2, 1, 1, 2, 3]

I hope one of these options will work for you. Then use the checksum function to do your calculation. I hope this is what you are looking for.