Comprehensions should be quite fast, although the only way to be sure is to time it.
On Fri, Jun 20, 2014 at 3:02 AM, Paul Analyst <[email protected]> wrote: > Thank you. > Do loops is the fastest way? I have a lot of such vectors ... Is it ready, > optimized command from combinatorics? > Paul > > W dniu 2014-06-19 21:55, Ethan Anderes pisze: > > … I probably should not have been sloppy about the typing the > comprehensions in my previous answer. I think this is probably better > > julia> x = [1,2,3] > 3-element Array{Int64,1}: > 1 > 2 > 3 > > julia> pairs_any = [[i,j] for i in x, j in x] |> vec > 9-element Array{Any,1}: > [1,1] > [2,1] > [3,1] > [1,2] > [2,2] > [3,2] > [1,3] > [2,3] > [3,3] > > julia> pairs_int = Vector{eltype(x)}[[i,j] for i in x, j in x] |> vec > 9-element Array{Array{Int64,1},1}: > [1,1] > [2,1] > [3,1] > [1,2] > [2,2] > [3,2] > [1,3] > [2,3] > [3,3] > > btw, I’m a bit puzzled what Array{Array{T,1},1} means when T is not > defined. This is what I get when I did the sloppy version > > julia> pairs_T = Vector[[i,j] for i in x, j in x] |> vec > 9-element Array{Array{T,1},1}: > [1,1] > [2,1] > [3,1] > [1,2] > [2,2] > [3,2] > [1,3] > [2,3] > [3,3] > > julia> T > ERROR: T not defined > > On Thursday, June 19, 2014 12:49:21 PM UTC-7, Ethan Anderes wrote: > >> Comprehensions will give you what you want >> >> x = [1,2,3] >> pairs = Vector[[i,j] for i in x, j in x] |> vec >> >> On Thursday, June 19, 2014 12:16:32 PM UTC-7, paul analyst wrote: >> >>> How to convert vector to a series of possible pairs of elements ? >>> >>> [1,2,3] >>> >>> I expect >>> >>> [1,1] [1,2] [1,3] [2,1] [2,2] [2,3] [3,1] [3,2] [3,3] >>> >>> >> > > > >
