Get same sequence of shuffle on Kotlin and Python

Question

I am shuffleing a list in Kotlin & Python using the same seed but i am getting different sequence. Cod on Python and Kotlin is as follows:

Kotlin

var trainInput = arrayListOf<Int>(1,2,3,4,5)
val randomSeed = 1549786796.toLong()
trainInput.shuffle(Random(randomSeed))

Output: [1, 3, 5, 2, 4]

Python:

import numpy as np
arr = np.array([1,2,3,4,5])
np.random.seed(1549786796)
np.random.shuffle(arr)

Ouput: [3 2 4 1 5]

Can anyone please point out how can I get the same sequence on both platforms?

Thanks.

EDIT I have also checked the library java-random (https://pypi.org/project/java-random/) suggested by Stef but this only generates the random number. I need to shuffle the list that generates the same sequence.

Java and numpy use different random number generators, so why do you expect them to yield the same results? See https://stackoverflow.com/questions/11162798/generating-the-same-random-number-in-java-and-python and in particular https://pypi.org/project/java-random/ — Stef, Jan 19 '21 at 08:04
@Stef: I am working on `Machine Learning` problem, I want to compare the results and for that to be the same, input sequence should have to be same. I was wondering, if I can get the same sequence. — Mustansar Saeed, Jan 19 '21 at 08:06
@Stef: `java-random` only generates the random number. I want to `shuffle` the list that generates the same sequence. — Mustansar Saeed, Jan 19 '21 at 09:57
Implement some simple random number generator (e.g. https://stackoverflow.com/a/3062783/51685) in both languages and use it to power your Fisher-Yates shuffle implementation? — AKX, Jan 19 '21 at 10:01
If you need the same input sequence, why not just make the input sequence the same? Forget about the randomisation. — voyager42, Jan 19 '21 at 13:12

score 1 · Accepted Answer · answered Jan 20 '21 at 07:08

Combining Stef and AKX answer produces the desired output. i.e., using java-random package on Python side to produce the same random number using same seed and then applying Fisher-Yates algorithm produces the same sequence.

import numpy as np
import javarandom as jrandom

r = jrandom.Random(1549786796)

arr = np.array([1, 2, 3, 4, 5, 6, 7, 8])

def randomize(arr, n):
    # Start from the last element and swap one by one. We don't
    # need to run for the first element that's why i > 0
    for i in range(n - 1, 0, -1):
        # Pick a random index from 0 to i
        j = r.nextInt(i + 1)

        # Swap arr[i] with the element at random index
        arr[i], arr[j] = arr[j], arr[i]
    return arr

Output: [7 5 1 4 6 2 3 8]

The above output is same on Kotlin and Python.

Thank you.

Get same sequence of shuffle on Kotlin and Python

1 Answers1