[julia-users] Re: distance.jl

[Jon Norberg]

Thank you very much Douglas! I learned a lot there. I didn't get it to work 
straight away (running julia studio so its using julia 0.2). But these 
changes made it work:

function subinds(k, N)

    step = iceil(N/k)

    rng = 1:step

    res = [rng + j * step for j in 0:k-2]

    push!(res, ((k - 1) * step + 1):N)

    res

end


function edist(a::AbstractMatrix, nblocks::Int, threshold)

    N = size(a,2)

    si = subinds(nblocks,N)

    i = Int[]

    j = Int[]

    x = eltype(a)[]

    for ii in si, jj in si

        #r = pairwise(Euclidean(), view(a,:,ii), view(a,:,jj))

        r = pairwise(Euclidean(), a[:,si[2]], a[:,si[2]])

        ioffset = ii[1] - 1

        joffset = jj[1] - 1

        for ir in 1:size(r,1), jr in 1:size(r,2)

            if (ie = ioffset + ir) != (je = joffset + jr) && (rij = r[ir,jr]) < 
threshold

                push!(i,ie)

                push!(j,je)

                push!(x,rij)

            end

        end

    end

    sparse(i,j,x)

end