What is a Pythonic way to get the exact same product for two arrays x and y, where y is x arbitrarily shuffled?

Question

I am trying to get the same result when I apply say some function product function prod(x) to x and shuffle(x) where x is some arbitrary array of integers say up to length 100, prod(x) is an function that returns the product of the entries of x, and shuffle is a function that returns x, shuffled.

ie

I want prod(x) == prod(shuffle(x)) to be True

Any help would be much appreciated. Here is a more tangible question how can I get True below?

import numpy as np

x = np.random.randint(100, 1000, 10)

x = np.asarray(x, dtype=np.float64)

xs = np.copy(x)

np.random.shuffle(xs)

y = np.prod(x)

ys = np.prod(xs)

print(y)

print(ys)

print(ys == y)

Answer 1

Since you have precision problem, why don't you use np.close to check within a tolerance rather than exact equality:

#replace (ys == y) with:
np.isclose(ys, y, rtol=1e-15, equal_nan=True)

rtol=1e-10 is relative tolerance (you can set it to your desired relative error, I recommend to set it to 15 or less (around 6 bytes=48 bits, I think float64 uses 52 bits for mantissa but I am not sure)). You can use atol argument for absolute tolerance instead of relative tolerance. equal_nan=True considers NaN s as equal (Set to False it you want nan s to be considered not equal).