# Towards an eachsliceX function
**URL:** https://discourse.julialang.org/t/towards-an-eachslicex-function/67145
**Category:** General Usage
**Created:** [August 27, 2021, 7:24pm UTC](https://discourse.julialang.org/t/towards-an-eachslicex-function/67145 "2021-08-27T19:24:36Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@Paul\_Soderlind](https://discourse.julialang.org/u/Paul_Soderlind)
#### Post date: [August 27, 2021, 7:24pm UTC](https://discourse.julialang.org/t/towards-an-eachslicex-function/67145/1 "2021-08-27T19:24:36Z")
`eachslice` does the opposite of what I would like. For instance, if `X` is a 3D array, then `eachslice(X,dims=1)` gives an iterator over 2D matrices. Rather, I would like an iterator over all ‘column vectors’, like `eachcol()`. The following code does that for arrays with 3 or fewer dimensions. (It’s straightforward to instead get iterators over rows or ‘aisles’)
Now, my questions is: is there a simple generalisation of this? If so, I think we should make a PR. Suggestions are welcome.
```julia
function eachcol3D(A::AbstractArray)
if 1 <= ndims(A) <= 2
z = eachcol(A) #(view(A,:,i) for i in axes(A,2))
elseif ndims(A) == 3
z = (view(A,:,i,j) for i in axes(A,2), j in axes(A,3))
else
error("this function works only on 1D-3D arrays")
end
return z
end
```
---
### Author:  [@jling](https://discourse.julialang.org/u/jling)
#### Post date: [August 27, 2021, 7:37pm UTC](https://discourse.julialang.org/t/towards-an-eachslicex-function/67145/2 "2021-08-27T19:37:22Z")
what’s the “physical” significance of such a column? you can easily reshape it into something that works with `eachcol`:
```julia
julia> a = rand(3,3,3)
julia> yours = first((view(a,:,i,j) for i in axes(a,2), j in axes(a,3)));
julia> first(eachcol(reshape(a, size(a,1), :))) == yours
true
```
I should note `reshape` is non-allocating, comment:
```julia
reshape(a, size(a,1), :)
```
makes a matrix such that each column is as tall as your original first dimension.
* * *
You can also create the same iterator (like your `z`) with:
```julia
Iterators.partition(vec(a), size(a,1))
```
`vec` also doesn’t allocate, it just presents the underlying memory as a 1D vector
---
### Author:  [@mcabbott](https://discourse.julialang.org/u/mcabbott)
#### Post date: [August 27, 2021, 7:50pm UTC](https://discourse.julialang.org/t/towards-an-eachslicex-function/67145/3 "2021-08-27T19:50:42Z")
> [@Paul\_Soderlind](#):
>
> we should make a PR.
There is [#32310](https://github.com/JuliaLang/julia/pull/32310), with which what you ask for is `eachslice(X, dims=(2,3))`.
---
### Author:  [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)
#### Post date: [August 30, 2021, 8:48am UTC](https://discourse.julialang.org/t/towards-an-eachslicex-function/67145/4 "2021-08-30T08:48:55Z")
I find
[https://github.com/bramtayl/JuliennedArrays.jl/](https://github.com/bramtayl/JuliennedArrays.jl/)
very useful for slicing.