Adding edges to graph

ckb_juliagraph2.jl

ew = Int[]
for i in 1:ncol(df), j in i+1:ncol(df) # iterate over all combinations of columns
    w = dot(df[!, i], df[!, j])        # calculate how many times (i,j) occurs
    if w > 0
        push!(ew, w)
        add_edge!(g, i, j, w)
    end
end