# [Numpy-discussion] How to speed up array generating

Kevin Sheppard kevin.k.sheppard at gmail.com
Sat Jan 9 16:13:17 EST 2021

```Actually I would try a broadcast multiply followed by ravel first.

Kevin

On Sat, Jan 9, 2021, 21:12 Kevin Sheppard <kevin.k.sheppard at gmail.com>
wrote:

> What about arange and then an integer divide or mod?
>
> Kevin
>
>
> On Sat, Jan 9, 2021, 20:54 <klark--kent at yandex.ru> wrote:
>
>> np.meshgrid, indexing, reshape
>>
>> 09.01.2021, 22:30, "Joseph Fox-Rabinovitz" <jfoxrabinovitz at gmail.com>:
>>
>> What other ways have you tried?
>>
>> On Sat, Jan 9, 2021 at 2:15 PM <klark--kent at yandex.ru> wrote:
>>
>> Hello. There is a random 1D array m_0 with size 3000, for example:
>>
>> m_0 = np.array([0, 1, 2])
>>
>> I need to generate two 1D arrays:
>>
>> m_1 = np.array([0, 1, 2, 0, 1, 2, 0, 1, 2])
>> m_2 = np.array([0, 0, 0, 1, 1, 1, 2, 2, 2])
>>
>> Is there faster way to do it than this one:
>>
>> import numpy as npimport time
>> N = 3
>> m_0 = np.arange(N)
>>
>> t = time.time()
>> m_1 = np.tile(m_0, N)
>> m_2 = np.repeat(m_0, N)
>> t = time.time() - t
>>
>> I tried other ways but they are slower or have the same time. Other NumPy operations in my code 10-100 times faster. Why the repeating an array is so slow? I need 10 times speed up. Thank you for your attantion to my problem.
>>
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>> ,
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