# \`sortrows\` and \`sortcols\` on \`SubArrays\`

**URL:** <https://discourse.julialang.org/t/sortrows-and-sortcols-on-subarrays/4381>\
**Category:** General Usage\
**Tags:** sort\
**Created:** [June 21, 2017, 1:24am UTC](https://discourse.julialang.org/t/sortrows-and-sortcols-on-subarrays/4381 "2017-06-21T01:24:44Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Hua-Zhou](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/hua-zhou/32/3270_2.png) [@Hua-Zhou](https://discourse.julialang.org/u/Hua-Zhou)\
**Post date:** [June 21, 2017, 1:24am UTC](https://discourse.julialang.org/t/sortrows-and-sortcols-on-subarrays/4381/1 "2017-06-21T01:24:44Z")

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Is there any reason the functions `sortrows` and `sortcols` don’t work on `SubArrays`?

```julia
julia> versioninfo()
Julia Version 0.6.0
Commit 903644385b (2017-06-19 13:05 UTC)
Platform Info:
  OS: macOS (x86_64-apple-darwin13.4.0)
  CPU: Intel(R) Core(TM) i7-6920HQ CPU @ 2.90GHz
  WORD_SIZE: 64
  BLAS: libopenblas (USE64BITINT DYNAMIC_ARCH NO_AFFINITY Haswell)
  LAPACK: libopenblas64_
  LIBM: libopenlibm
  LLVM: libLLVM-3.9.1 (ORCJIT, skylake)

julia> srand(123); A = rand(0:1, 5, 3)
5×3 Array{Int64,2}:
 0 1 1
 0 0 1
 0 1 1
 0 0 0
 1 1 0

julia> Av = view(A, [2; 4; 5], [2; 3])
3×2 SubArray{Int64,2,Array{Int64,2},Tuple{Array{Int64,1},Array{Int64,1}},false}:
 0 1
 0 0
 1 0

julia> sortrows(Av)
ERROR: MethodError: Cannot `convert` an object of type SubArray{Int64,1,Array{Int64,2},Tuple{Int64,Array{Int64,1}},false} to an object of type SubArray{Int64,1,SubArray{Int64,2,Array{Int64,2},Tuple{Array{Int64,1},Array{Int64,1}},false},Tuple{Int64,Base.Slice{Base.OneTo{Int64}}},false}
This may have arisen from a call to the constructor SubArray{Int64,1,SubArray{Int64,2,Array{Int64,2},Tuple{Array{Int64,1},Array{Int64,1}},false},Tuple{Int64,Base.Slice{Base.OneTo{Int64}}},false}(...),
since type constructors fall back to convert methods.
Stacktrace:
 [1] #sortrows#14(::Array{Any,1}, ::Function, ::SubArray{Int64,2,Array{Int64,2},Tuple{Array{Int64,1},Array{Int64,1}},false}) at ./sort.jl:776
 [2] sortrows(::SubArray{Int64,2,Array{Int64,2},Tuple{Array{Int64,1},Array{Int64,1}},false}) at ./sort.jl:772

```

Similar for `sortcols`.

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**Author:** ![joshday](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/joshday/32/368_2.png) [@joshday](https://discourse.julialang.org/u/joshday)\
**Post date:** [June 21, 2017, 8:45pm UTC](https://discourse.julialang.org/t/sortrows-and-sortcols-on-subarrays/4381/2 "2017-06-21T20:45:19Z")

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This is a bug. Here is the definition of `sortrows`:

```julia
function sortrows(A::AbstractMatrix; kws...)
    inds = indices(A,1)
    T = slicetypeof(A, inds, :)
    rows = similar(Vector{T}, indices(A, 1))
    for i in inds
        rows[i] = view(A, i, :)
    end
    p = sortperm(rows; kws..., order=Lexicographic)
    A[p,:]
end

```

`Base.Sort.slicetypeof` returns the wrong type for a SubArray so types don’t match in `rows[i] = view(A, i, :)`

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<div class="post-metadata">

**Author:** ![Hua-Zhou](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/hua-zhou/32/3270_2.png) [@Hua-Zhou](https://discourse.julialang.org/u/Hua-Zhou)\
**Post date:** [June 21, 2017, 11:11pm UTC](https://discourse.julialang.org/t/sortrows-and-sortcols-on-subarrays/4381/3 "2017-06-21T23:11:52Z")

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All right. I’ll open an issue if nobody disagrees it’s bug for another day or two.

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<div class="post-metadata">

**Author:** ![Hua-Zhou](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/hua-zhou/32/3270_2.png) [@Hua-Zhou](https://discourse.julialang.org/u/Hua-Zhou)\
**Post date:** [June 23, 2017, 5:31pm UTC](https://discourse.julialang.org/t/sortrows-and-sortcols-on-subarrays/4381/4 "2017-06-23T17:31:16Z")

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Opened an issue [https://github.com/JuliaLang/julia/issues/22493](https://github.com/JuliaLang/julia/issues/22493)