10000 BUG: Change in random number sequence when np.random.RandomState.choice is used · Issue #28078 · numpy/numpy · GitHub
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BUG: Change in random number sequence when np.random.RandomState.choice is used #28078

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SelinBayramoglu opened this issue Dec 30, 2024 · 1 comment
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BUG: Change in random number sequence when np.random.RandomState.choice is used #28078

SelinBayramoglu opened this issue Dec 30, 2024 · 1 comment
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33 - Question Question about NumPy usage or development

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@SelinBayramoglu
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SelinBayramoglu commented Dec 30, 2024 •
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Describe the issue:

I create a random number generator (rng) with a seed to get a reproducible list of random numbers. The first two numbers in this list are num1 and num2. Before generating these numbers, I use the choice() to pick a value in a list. When I generate two numbers again, I get num3 and num4. I expected num2 and num3 to be the same, since they are generated when rng is called twice. However, I get different numbers.

Reproduce the code example:

import numpy as np

rng = np.random.RandomState(0)

num1 = rng.rand()
num2 = rng.rand()

print(num1, num2)
# 0.5488135039273248 0.7151893663724195

alist = range(1,101)

rng = np.random.RandomState(0)

a = rng.choice(alist)
num3 = rng.rand()
num4 = rng.rand()

print(num3, num4)
# 0.5928446182250183 0.8442657485810173

Error message:

No response

Python and NumPy Versions:

Numpy version: 1.26.2
Python version: 3.9.18 (main, Sep 11 2023, 13:21:18)
[GCC 11.2.0]

Runtime Environment:

[{'numpy_version': '1.26.2',
'python': '3.9.18 (main, Sep 11 2023, 13:21:18) \n[GCC 11.2.0]',
'uname': uname_result(system='Linux', node='atl1-1-02-003-16-1.pace.gatech.edu', release='5.14.0-427.26.1.el9_4.x86_64', version='#1 SMP PREEMPT_DYNAMIC Fri Jul 5 11:34:54 EDT 2024', machine='x86_64')},
{'simd_extensions': {'baseline': ['SSE', 'SSE2', 'SSE3'],
'found': ['SSSE3',
'SSE41',
'POPCNT',
'SSE42',
'AVX',
'F16C',
'FMA3',
'AVX2',
'AVX512F',
'AVX512CD',
'AVX512_SKX',
'AVX512_CLX'],
'not_found': ['AVX512_KNL',
'AVX512_KNM',
'AVX512_CNL',
'AVX512_ICL']}},
{'architecture': 'SkylakeX',
'filepath': '/storage/home/hcoda1/0/sbayramoglu3/.local/lib/python3.9/site-packages/numpy.libs/libopenblas64_p-r0-0cf96a72.3.23.dev.so',
'internal_api': 'openblas',
'num_threads': 4,
'prefix': 'libopenblas',
'threading_layer': 'pthreads',
'user_api': 'blas',
'version': '0.3.23.dev'}]

Context for the issue:

No response
@rkern rkern added 33 - Question Question about NumPy usage or development and removed 00 - Bug labels Dec 30, 2024
@rkern
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rkern commented Dec 30, 2024

This is expected. choice() consumes more iterations of the core PRNG that rand() does (depending on the size of the input).

@rkern rkern closed this as n 4EEF ot planned Won't fix, can't repro, duplicate, stale Dec 30, 2024
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