FYI Array{AbstractFloat}[] will be slow to work with because the you are
saying that in each Array the elements can be of any floating type. That
means that it would be valid to have an array with a Float32 followed by a
Float64 and then some other user defined type that happens to be a subtype
of AbstractFloat etc. By doing so it is impossible for the compiler to know
the memory structure of the array and what method to dispatch to on each
element. For performance you want to use concrete types, like for example
Array{Float64, 1}.
On Monday, January 4, 2016 at 1:48:07 PM UTC+1, Charles Santana wrote:
>
> Hi people,
>
> I would like to work with matrices represented as Arrays of Arrays of
> AbstractFloats. Something like this:
>
> F=Array{AbstractFloat}[];#initialize the matrix F as an Array of
> Arrays of Float
> for (i in 1:10)
> Fi = Array(AbstractFloat,0);#initialize the vector Fi as an
> Array of Float
> for (k in 1:5)
> push!(Fi,k^2+i^2)
> end#end-fork
> push!(F,Fi);
> end#end-fori
>
> typeof(F)
> Array{Array{AbstractFloat,N},1}
>
> But I am experiencing problems to work with rows/columns of such Arrays. I
> would like to calculate the logarithm of the square of elements of those
> rows/columns like this:
>
> f = F[1];#a vector of AbstractFloat
>
> typeof(f)
> Array{AbstractFloat,1}
>
> typeof(f.^2)
> Array{Any,1}
>
> log(f.^2)
> ERROR: MethodError: `log` has no method matching
> log(::Array{Any,1})
>
>
> I understand this error only happens because I am working with Arrays of
> Arrays of AbstractFloats. If I run a similar code using a Matrix instead of
> Array I don't have such problems:
>
> A = rand(10,5);#a matrix of floats (similar to an array of arrays)
>
> typeof(A)
> Array{Float64,2}
>
> a = A[1,:];#a vector of Float
>
> typeof(a)
> Array{Float64,2}
>
> typeof(a.^2)
> Array{Float64,2}
>
> log(a.^2)
>
>
> everything runs smoothly.
>
> My question: Am I doing something wrong in the way I am dealing with the
> Array of Arrays of AbstractFloat? Should I convert it to a Matrix? Or
> should I convert its elements to Array of Float instead of Array of Any?
> Any other suggestion?
>
> Thanks for your attention and for any advice!
>
> Charles
>
> --
> Um axé! :)
>
> --
> Charles Novaes de Santana, PhD
> http://www.imedea.uib-csic.es/~charles
>
