Odtnhj

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?

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)

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

def convertObjectIntoFixedLengthNumeric(obj):
 return 17

x = Car(brand='toyota', model='corolla', price='10000', year=1997)
convertObjectIntoFixedLengthNumeric(x)
17

Very convenient and generic. If not what you were looking for, provide some more information..

You may want to look at the built-in id-function. It returns the memory adress of an object which is always unique, as long as you do not compare the id of an already garbage collected object.

Take all the attributes you care about and hash them.

class Car(...):
 ...
 def __hash__(self):
 return hash((self.brand, self.model, self.price, self.year))

 ...

print hash(x)

Youre talking about a hash function. I think you need to give more info as to what you need this for to get helpful answers.