Is there a way to transpose an array of Any? I have a `12×500 Array{Any, 2}` I want

General Usage
1

Is there a way to transpose an array of Any? I have a 12×500 Array{Any,2} I want it to be 500x12. If I do transpose it throws an error.

500×12 LinearAlgebra.Transpose{Any,Array{Any,2}}:
Error showing value of type LinearAlgebra.Transpose{Any,Array{Any,2}}:
ERROR: MethodError: no method matching transpose(::String)
Closest candidates are:
  transpose(::Missing) at missing.jl:100
  transpose(::Number) at number.jl:168
  transpose(::LinearAlgebra.Transpose) at D:\buildbot\worker\package_win64\build\usr\share\julia\stdlib\v1.5\LinearAlgebra\src\adjtrans.jl:165

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2

In Julia, transpose is firmly rooted in linear algebra, but permutedims allows swapping of dimensions of any type of object. In other words,

julia> A = Any["hello" for i = 1:3, j=1:2]
3×2 Matrix{Any}:
 "hello"  "hello"
 "hello"  "hello"
 "hello"  "hello"

julia> permutedims(A, (2, 1))
2×3 Matrix{Any}:
 "hello"  "hello"  "hello"
 "hello"  "hello"  "hello"

julia> transpose(A)
2×3 transpose(::Matrix{Any}) with eltype Any:
Error showing value of type Transpose{Any, Matrix{Any}}:
ERROR: MethodError: no method matching transpose(::String)
...

Why the distinction? Well, notice that the error message is telling you it’s trying to take transpose(::String), which isn’t a defined operation. Why does it take the transpose of elements? It’s useful/necessary for generic linear algebra, as one can see with this vector-of-vectors:

julia> x = [[1,2], [10,11]]
2-element Vector{Vector{Int64}}:
 [1, 2]
 [10, 11]

julia> x'*x
226

julia> x[1]'*x[1] + x[2]'*x[2]
226

So not only does it reshape the container x, it also reshapes each element.

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3

For anyone looking to get involved in Julia development, here’s an issue to get your feet wet: https://github.com/JuliaLang/julia/issues/39938

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