# In-place reverse!

**URL:** <https://discourse.julialang.org/t/in-place-reverse/47524>\
**Category:** General Usage\
**Created:** [September 30, 2020, 6:40am UTC](https://discourse.julialang.org/t/in-place-reverse/47524 "2020-09-30T06:40:30Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![greg\_plowman](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/greg_plowman/32/8100_2.png) [@greg\_plowman](https://discourse.julialang.org/u/greg_plowman)\
**Post date:** [September 30, 2020, 6:40am UTC](https://discourse.julialang.org/t/in-place-reverse/47524/1 "2020-09-30T06:40:30Z")

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In-place `reverse!` is defined for vectors.  
Does it make sense to have `reverse!` for general arrays with other dimensions?  
In particular, I thought it might useful for matrices?

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**Author:** ![Tamas\_Papp](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/tamas_papp/32/25949_2.png) [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)\
**Post date:** [September 30, 2020, 9:26am UTC](https://discourse.julialang.org/t/in-place-reverse/47524/2 "2020-09-30T09:26:12Z")

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This depends on your use case; since `reverse` supports this it would be a natural extension. I guess it’s just that no one got around to writing it yet.

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**Author:** ![giordano](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/giordano/32/2166_2.png) [@giordano](https://discourse.julialang.org/u/giordano)\
**Post date:** [September 30, 2020, 10:10am UTC](https://discourse.julialang.org/t/in-place-reverse/47524/3 "2020-09-30T10:10:03Z")

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> [@greg\_plowman](#):
>
> In particular, I thought it might useful for matrices?

Uh?

```julia
julia> A = rand(2,2)
2×2 Matrix{Float64}:
 0.664925 0.689702
 0.987743 0.960874

julia> reverse!(A)
2×2 Matrix{Float64}:
 0.960874 0.987743
 0.689702 0.664925

julia> A
2×2 Matrix{Float64}:
 0.960874 0.987743
 0.689702 0.664925

```

_Edit_: this is Julia v1.6, probably not available in v1.5-. This is mentioned in [`NEWS.md`](https://github.com/JuliaLang/julia/blob/395e47f4da4630a521333ad67eccf614c56aaf9c/NEWS.md#standard-library-changes) for Julia v1.6.

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**Author:** ![fbanning](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/fbanning/32/14972_2.png) [@fbanning](https://discourse.julialang.org/u/fbanning)\
**Post date:** [September 30, 2020, 10:15am UTC](https://discourse.julialang.org/t/in-place-reverse/47524/4 "2020-09-30T10:15:00Z")

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Yep, doesn’t work on 1.5.2.

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<div class="post-metadata">

**Author:** ![greg\_plowman](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/greg_plowman/32/8100_2.png) [@greg\_plowman](https://discourse.julialang.org/u/greg_plowman)\
**Post date:** [September 30, 2020, 11:24am UTC](https://discourse.julialang.org/t/in-place-reverse/47524/5 "2020-09-30T11:24:33Z")

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Ha, ha. Thanks for that!