Bigarray.c_layout
 Florent Monnier
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Date:   (:) 
From:  Florent Monnier <fmonnier@l...> 
Subject:  Bigarray.c_layout 
Hi, My problem is with the Bigarray.c_layout All the items are ordered row by row in OCaml with this layout, and the library I use through OCaml use the datas ordered line by line. As a temporary workaround, I've made the function 'reorder' below. But this way is very too slow. So what solution would you advice to me ?  creating an other Bigarray.c_layout : "Bigarray.c_layout_by_line" ? (and then propose it as a patch to be included in a futur OCaml version)  or replacing my big arrays of 3 dimensions by big arrays of 1 dimension and creating a function which converts the index i j k by the unique index ?  something else ?  best regards ========================= let reorder_c_to_ml ~arr = let width = Array3.dim1 arr and height = Array3.dim2 arr and cells = Array3.dim3 arr and kind = Array3.kind arr in assert(cells=3); let tmp = Array1.create kind c_layout (width * height * cells) and k = ref 0 in for i = 0 to pred(width) do for j = 0 to pred(height) do tmp.{!k} < arr.{i,j,0}; incr k; tmp.{!k} < arr.{i,j,1}; incr k; tmp.{!k} < arr.{i,j,2}; incr k; done; done; k := 0; for j = 0 to pred(height) do for i = 0 to pred(width) do arr.{i,j,0} < tmp.{!k}; incr k; arr.{i,j,1} < tmp.{!k}; incr k; arr.{i,j,2} < tmp.{!k}; incr k; done; done; (arr) ;; let reorder_ml_to_c ~arr = let width = Array3.dim1 arr and height = Array3.dim2 arr and cells = Array3.dim3 arr and kind = Array3.kind arr in assert(cells=3); let tmp = Array1.create kind c_layout (width * height * cells) and k = ref 0 in for j = 0 to pred(height) do for i = 0 to pred(width) do tmp.{!k} < arr.{i,j,0}; incr k; tmp.{!k} < arr.{i,j,1}; incr k; tmp.{!k} < arr.{i,j,2}; incr k; done; done; k := 0; for i = 0 to pred(width) do for j = 0 to pred(height) do arr.{i,j,0} < tmp.{!k}; incr k; arr.{i,j,1} < tmp.{!k}; incr k; arr.{i,j,2} < tmp.{!k}; incr k; done; done; (arr) ;; type dir = ML_to_C  C_to_ML let reorder ~arr ?(dir=ML_to_C) () = match dir with  ML_to_C > reorder_ml_to_c ~arr  C_to_ML > reorder_c_to_ml ~arr ;;