Question

I basically want to convert a Python object into a fixed length numeric (not alphanumeric) value. One way, I’ve come up with is,

import random
x = Car(brand='toyota', model='corolla', price='10000', year=1997)
random.seed(x)

random.random()
0.13436424411240122

random.seed(x)
random.random()
0.13436424411240122

I’m wondering if there is more convenient and generic way (or library) to make this work?

Answer 1

The way you’re now using is:

• Prone to typo error in your Car object.
• Fragile if you forget to call random.seed() every time.
• Case sensitive.

Also, if I were you, I’d like to have a little control on how my number is generated.

The other answers have already showed to you the existence of hashlib.

I would probably use it like this:

class Car:
    # ...
    def __hash__(self):
        md5 = hashlib.md5()
        for i in ('brand', 'model', 'price', 'year'):
            attr = getattr(self, i)
            md5.update(str(attr).lowercase())
        return int(md5.hexdigest(), 16)

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Reference on the integer conversion: Convert 32-char md5 string to integer.