# Array dimensions don't match

**URL:** <https://discourse.julialang.org/t/array-dimensions-dont-match/75442>\
**Category:** General Usage\
**Tags:** array\
**Created:** [January 30, 2022, 2:29am UTC](https://discourse.julialang.org/t/array-dimensions-dont-match/75442 "2022-01-30T02:29:55Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![chunquan](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/chunquan/32/33303_2.png) [@chunquan](https://discourse.julialang.org/u/chunquan)\
**Post date:** [January 30, 2022, 2:29am UTC](https://discourse.julialang.org/t/array-dimensions-dont-match/75442/1 "2022-01-30T02:29:55Z")

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Hello, I used  
x, y =MNIST.testdata()  
and then did this  
“x = (x .- mean(x,dims = 2)) / std(x .- mean(x,dims = 2))”  
And I get 28_28_10000 Array{Float64, 3}.  
But actually I need an Array 784\*10000, which means this should be a 2 dimensional array with 10000 entries, each entry is a 1 dimensional array with 784 elements…  
what can I do? Thanks in advance!

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**Author:** ![Joris\_Pinkse](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/joris_pinkse/32/216398_2.png) [@Joris\_Pinkse](https://discourse.julialang.org/u/Joris_Pinkse)\
**Post date:** [January 30, 2022, 3:25am UTC](https://discourse.julialang.org/t/array-dimensions-dont-match/75442/2 "2022-01-30T03:25:19Z")

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The x that is read is 28 \* 28 \* 10000. I’m not entirely sure what you want but perhaps replacing x with reshape( x, 784, 10000 ) right after loading does the trick?

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<div class="post-metadata">

**Author:** ![chunquan](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/chunquan/32/33303_2.png) [@chunquan](https://discourse.julialang.org/u/chunquan)\
**Post date:** [January 30, 2022, 8:22pm UTC](https://discourse.julialang.org/t/array-dimensions-dont-match/75442/3 "2022-01-30T20:22:05Z")

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Thanks! It worked!