# Create random numbers into a same array

**URL:** https://discourse.julialang.org/t/create-random-numbers-into-a-same-array/53766
**Category:** Modelling & Simulations
**Created:** [January 22, 2021, 8:14am UTC](https://discourse.julialang.org/t/create-random-numbers-into-a-same-array/53766 "2021-01-22T08:14:13Z")
**Posts on this page:** 3
**Page:** 1

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### Author: ![Xijiang\_Yu](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/xijiang_yu/32/14439_2.png) [@Xijiang\_Yu](https://discourse.julialang.org/u/Xijiang_Yu)
#### Post date: [January 22, 2021, 8:14am UTC](https://discourse.julialang.org/t/create-random-numbers-into-a-same-array/53766/1 "2021-01-22T08:14:13Z")

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Is there any way to create random numbers into a same array? I am simulating using `rand(n)` ~1M times, i.e. to determine snp allele to drop into the next generation. This causes a lot of allocations.

Or is there some better way to simulate.

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### Author: ![marius311](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/marius311/32/3953_2.png) [@marius311](https://discourse.julialang.org/u/marius311)
#### Post date: [January 22, 2021, 8:24am UTC](https://discourse.julialang.org/t/create-random-numbers-into-a-same-array/53766/2 "2021-01-22T08:24:45Z")

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Maybe [rand!](https://docs.julialang.org/en/v1/stdlib/Random/#Random.rand!) is what you need?

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### Author: ![Xijiang\_Yu](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/xijiang_yu/32/14439_2.png) [@Xijiang\_Yu](https://discourse.julialang.org/u/Xijiang_Yu)
#### Post date: [January 22, 2021, 8:33am UTC](https://discourse.julialang.org/t/create-random-numbers-into-a-same-array/53766/3 "2021-01-22T08:33:06Z")

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Many thanks. I didn’t read the docs enough.