以62为基数的转换 [英] Base 62 conversion

问题描述

如何将整数转换为以62为底的整数(类似于十六进制，但具有以下数字:'0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ').

How would you convert an integer to base 62 (like hexadecimal, but with these digits: '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ').

我一直在努力寻找一个好的Python库，但是它们似乎都被转换字符串所占据. Python base64模块仅接受字符串，并将一个数字转换为四个字符.我正在寻找类似于URL缩短器使用的东西.

I have been trying to find a good Python library for it, but they all seems to be occupied with converting strings. The Python base64 module only accepts strings and turns a single digit into four characters. I was looking for something akin to what URL shorteners use.

推荐答案

对此没有标准模块，但是我编写了自己的函数来实现.

There is no standard module for this, but I have written my own functions to achieve that.

BASE62 = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"

def encode(num, alphabet=BASE62):
    """Encode a positive number in Base X

    Arguments:
    - `num`: The number to encode
    - `alphabet`: The alphabet to use for encoding
    """
    if num == 0:
        return alphabet[0]
    arr = []
    base = len(alphabet)
    while num:
        num, rem = divmod(num, base)
        arr.append(alphabet[rem])
    arr.reverse()
    return ''.join(arr)

def decode(string, alphabet=BASE62):
    """Decode a Base X encoded string into the number

    Arguments:
    - `string`: The encoded string
    - `alphabet`: The alphabet to use for encoding
    """
    base = len(alphabet)
    strlen = len(string)
    num = 0

    idx = 0
    for char in string:
        power = (strlen - (idx + 1))
        num += alphabet.index(char) * (base ** power)
        idx += 1

    return num

请注意，您可以给它任何字母以用于编码和解码.如果不使用alphabet参数，则将获得在第一行代码中定义的62个字符的字母，从而对62个基数进行编码/解码.

Notice the fact that you can give it any alphabet to use for encoding and decoding. If you leave the alphabet argument out, you are going to get the 62 character alphabet defined on the first line of code, and hence encoding/decoding to/from 62 base.

希望这会有所帮助.

PS-对于URL缩短器，我发现最好省略一些令人困惑的字符，例如0Ol1oI等.因此，我将此字母用于我的URL缩短要求-"23456789abcdefghijkmnpqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ"

PS - For URL shorteners, I have found that it's better to leave out a few confusing characters like 0Ol1oI etc. Thus I use this alphabet for my URL shortening needs - "23456789abcdefghijkmnpqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ"

玩得开心.

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