Re: sorting of list of vectors (array with one dimension)

[Judicael Courant <Judicael.Courant@lri.fr>]

Mattias Waldau a écrit :
> 
> I have a list of vectors, I would like to sort according to the first
> vector, and move the corresponding data in the other vectors.
> 
> Is there a function for this (for example, a sort function, where I add a
> function that is called each time data is swapped) or do I have to write a
> quicksort in ocaml.
> 
> /mattias

Maybe you are not using the right data representation ? Things would be
much simpler if you used a vector of lists instead of a list of vectors
; just a matter of

Array.sort (fun l1 l2 -> compare (List.hd l1) (List.hd l2)) lv

Now, you can easily convert your initial representation to this one as
follows (untested code):

(* get : int -> 'a array list -> 'a list *)
let get i vl = List.map (fun t -> t.(i)) vl

(* lv_of_vl : 'a array list -> 'a list array *)
let lv_of_vl vl =
  Array.init (Array.length (List.hd vl))
             (fun i -> get i vl)

(* set : int -> 'a list -> 'a array list -> unit *)
let set i l vl =
  List.iter2 (fun x t -> t.(i) <- x) l vl

(* vl_of_lv : 'a list array -> 'a array list -> unit *)
let vl_of_lv lv vl =
   Array.iteri (fun i l -> set i l vl) lv


Sincerly yours,

Judicaël.
-- 
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