# Accessing sets of particular indexes over multiple dimensions

**URL:** <https://discourse.julialang.org/t/accessing-sets-of-particular-indexes-over-multiple-dimensions/10067>\
**Category:** General Usage\
**Created:** [March 30, 2018, 2:36am UTC](https://discourse.julialang.org/t/accessing-sets-of-particular-indexes-over-multiple-dimensions/10067 "2018-03-30T02:36:49Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![abshej](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/abshej/32/3216_2.png) [@abshej](https://discourse.julialang.org/u/abshej)\
**Post date:** [March 30, 2018, 2:36am UTC](https://discourse.julialang.org/t/accessing-sets-of-particular-indexes-over-multiple-dimensions/10067/1 "2018-03-30T02:36:49Z")

</div>

How can you use maps or other techniques to instantly access every _nth_ element of every _mth_ element of every _kth_ element of every element of multidimensional array? Is that allowed?

```julia
# array def
a = Array{Vector{Vector{SparseVector}}}(a, b)

```

---

<div class="post-metadata">

**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:** [March 30, 2018, 6:40am UTC](https://discourse.julialang.org/t/accessing-sets-of-particular-indexes-over-multiple-dimensions/10067/2 "2018-03-30T06:40:18Z")

</div>

A minimal working example would be nice, but something like

```julia
function nested(A, k, m, n)
    _acc(i) = B -> B[i]
    map(_acc(n) ∘_acc(m) ∘ _acc(k), A)
end

```

should work, if I parsed the “… of …” nesting right.

---

<div class="post-metadata">

**Author:** ![abshej](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/abshej/32/3216_2.png) [@abshej](https://discourse.julialang.org/u/abshej)\
**Post date:** [March 30, 2018, 7:04am UTC](https://discourse.julialang.org/t/accessing-sets-of-particular-indexes-over-multiple-dimensions/10067/3 "2018-03-30T07:04:43Z")

</div>

```julia
function kmnofa(a)
    el=[]
    for i in eachindex(a)
         push!(el, a[i][k][m][n])
    end
    return el
end

```