# 2 dimensional array to one dimensional

**URL:** <https://discourse.julialang.org/t/2-dimensional-array-to-one-dimensional/32574>\
**Category:** General Usage\
**Created:** [December 22, 2019, 1:16pm UTC](https://discourse.julialang.org/t/2-dimensional-array-to-one-dimensional/32574 "2019-12-22T13:16:27Z")\
**Posts on this page:** 7\
**Page:** 1

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**Author:** ![imrankhan\_juliaLang](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/imrankhan_julialang/32/12020_2.png) [@imrankhan\_juliaLang](https://discourse.julialang.org/u/imrankhan_juliaLang)\
**Post date:** [December 22, 2019, 1:16pm UTC](https://discourse.julialang.org/t/2-dimensional-array-to-one-dimensional/32574/1 "2019-12-22T13:16:27Z")

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how can i make 2 dimensional array to one dimensional

**Like**

`arr = [[1,2], [3,4]]`  
To  
`one, two, three, four = something to transport`

**NB: Is like numpy ravel method**

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**Author:** ![yha](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/yha/32/3502_2.png) [@yha](https://discourse.julialang.org/u/yha)\
**Post date:** [December 22, 2019, 1:29pm UTC](https://discourse.julialang.org/t/2-dimensional-array-to-one-dimensional/32574/2 "2019-12-22T13:29:32Z")

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You’re looking for `vec`

```julia
help?> vec
search: vec Vector VecOrMat VecElement BitVector DenseVector DenseVecOrMat StridedVector StridedVecOrMat AbstractVector

  vec(a::AbstractArray) -> AbstractVector

  Reshape the array a as a one-dimensional column vector. Return a if it is already an AbstractVector. The resulting
  array shares the same underlying data as a, so it will only be mutable if a is mutable, in which case modifying one
  will also modify the other.

  Examples
  ≡≡≡≡≡≡≡≡≡≡

  julia> a = [1 2 3; 4 5 6]
  2×3 Array{Int64,2}:
   1 2 3
   4 5 6

  julia> vec(a)
  6-element Array{Int64,1}:
   1
   4
   2
   5
   3
   6

  julia> vec(1:3)
  1:3

  See also reshape.

```

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<div class="post-metadata">

**Author:** ![fredrikekre](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/fredrikekre/32/1688_2.png) [@fredrikekre](https://discourse.julialang.org/u/fredrikekre)\
**Post date:** [December 22, 2019, 1:31pm UTC](https://discourse.julialang.org/t/2-dimensional-array-to-one-dimensional/32574/3 "2019-12-22T13:31:17Z")

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[`Iterators.flatten`](https://docs.julialang.org/en/v1/base/iterators/#Base.Iterators.flatten) (which you can materialize with `collect`):

```julia
julia> arr = [[1,2], [3,4]];                                              
                                                                          
julia> it = Iterators.flatten(arr)                                        
Base.Iterators.Flatten{Array{Array{Int64,1},1}}(Array{Int64,1}[[1, 2], [3,
 4]])                                                                     
                                                                          
julia> collect(it)                                                        
4-element Array{Int64,1}:                                                 
 1                                                                        
 2                                                                        
 3                                                                        
 4

```

Note though that `arr` from your example is not two dimensional; it is a one dimensional array containing one dimensional arrays.

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<div class="post-metadata">

**Author:** ![imrankhan\_juliaLang](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/imrankhan_julialang/32/12020_2.png) [@imrankhan\_juliaLang](https://discourse.julialang.org/u/imrankhan_juliaLang)\
**Post date:** [December 22, 2019, 1:48pm UTC](https://discourse.julialang.org/t/2-dimensional-array-to-one-dimensional/32574/4 "2019-12-22T13:48:57Z")

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> [@fredrikekre](#):
>
> it = Iterators.flatten(arr)

thank you so much for help

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<div class="post-metadata">

**Author:** ![imrankhan\_juliaLang](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/imrankhan_julialang/32/12020_2.png) [@imrankhan\_juliaLang](https://discourse.julialang.org/u/imrankhan_juliaLang)\
**Post date:** [December 22, 2019, 1:49pm UTC](https://discourse.julialang.org/t/2-dimensional-array-to-one-dimensional/32574/5 "2019-12-22T13:49:17Z")

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thank you so much for help

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<div class="post-metadata">

**Author:** ![StevenSiew](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/stevensiew/32/218393_2.png) [@StevenSiew](https://discourse.julialang.org/u/StevenSiew)\
**Post date:** [December 23, 2019, 1:53am UTC](https://discourse.julialang.org/t/2-dimensional-array-to-one-dimensional/32574/6 "2019-12-23T01:53:54Z")

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> [@imrankhan\_juliaLang](#):
>
> arr = [[1,2], [3,4]]

```julia
julia> arr = [[1,2], [3,4]]
2-element Array{Array{Int64,1},1}:
 [1, 2]
 [3, 4]

julia> vcat(arr...)
4-element Array{Int64,1}:
 1
 2
 3
 4

```

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<div class="post-metadata">

**Author:** ![imrankhan\_juliaLang](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/imrankhan_julialang/32/12020_2.png) [@imrankhan\_juliaLang](https://discourse.julialang.org/u/imrankhan_juliaLang)\
**Post date:** [December 23, 2019, 2:56am UTC](https://discourse.julialang.org/t/2-dimensional-array-to-one-dimensional/32574/7 "2019-12-23T02:56:28Z")

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It’s work too…  
thank you