tk/Dataframe: added test and fixed bug

lib/toolbox/dataframe.ml

@@ -8,6 +8,7 @@ type column =
   | Maybe_float of float option array
   | String of string array
   | Maybe_string of string option array
+[@@deriving show]
 
 type t = {
   nrows : int ;
@@ -55,7 +56,7 @@ let rev_convert_col col =
   else
     try Int (conv Int.of_string) with _ ->
     try Float (conv Float.of_string) with _ ->
-    String (Array.of_list col)
+    String (Array.of_list_rev col)
 
 let parse_lines ncols lines =
   let open Result.Monad_infix in
@@ -68,6 +69,24 @@ let parse_lines ncols lines =
     ) >>| fun (nrows, cols) ->
   nrows, List.map cols ~f:rev_convert_col
 
+type parse_result = (int * column list, [`Msg of string]) result
+[@@deriving show]
+
+let%expect_test "Dataframe.parse_line ex1" =
+  let got =
+    parse_lines 3 [
+      "a\t1.2\tNA" ;
+      "a\t1.2\t2" ;
+      "c\t-1.2\tNA" ;
+    ]
+  in
+  print_endline (show_parse_result got) ;
+  [%expect {|
+    (Ok (3,
+         [(Dataframe.String [|"a"; "a"; "c"|]);
+           (Dataframe.Float [|1.2; 1.2; -1.2|]);
+           (Dataframe.Maybe_int [|None; (Some 2); None|])])) |}]
+
 let from_file path =
   let open Result.Monad_infix in
   match In_channel.read_lines path with

lib/toolbox/dune

@@ -5,4 +5,4 @@
  (inline_tests
   (deps ../../tests/data/gemma_output.tsv ../../tests/data/gemma_alignment.fa))
  (preprocess
-  (pps ppx_jane ppx_inline_test)))
+  (pps ppx_jane ppx_inline_test ppx_deriving.show)))