clone_nodes, gmap and export functions

src/ftest.ml

@@ -1,4 +1,5 @@
 open Gfile
+open Tool
 
 let () =
 
@@ -24,7 +25,7 @@ let () =
   let graph = from_file infile in
 
   (* Rewrite the graph that has been read. *)
-  let () = write_file outfile graph in
+  let () = write_file outfile (gmap graph (fun lbl -> string_of_int (int_of_string lbl *2) ) ) in
-
+  let () = export outfile graph in
   ()
 

src/gfile.ml

@@ -35,6 +35,8 @@ let write_file path graph =
 
   fprintf ff "\n%% End of graph\n" ;
 
+  
+
   close_out ff ;
   ()
 
@@ -44,7 +46,7 @@ let read_node id graph line =
   with e ->
     Printf.printf "Cannot read node in line - %s:\n%s\n%!" (Printexc.to_string e) line ;
     failwith "from_file"
-
+    
 (* Ensure that the given node exists in the graph. If not, create it. 
  * (Necessary because the website we use to create online graphs does not generate correct files when some nodes have been deleted.) *)
 let ensure graph id = if node_exists graph id then graph else new_node graph id
@@ -99,3 +101,19 @@ let from_file path =
   close_in infile ;
   final_graph
 
+
+(* Write the graph in a .dot file*)
+let export path graph =
+  (* Open a write-file. *)
+  let ff = open_out (path^".dot") in
+
+  (* Write in this file. *)
+  fprintf ff "digraph graphique1 {\n\tsize=\"20\"\n\tnode [shape = circle];\n";
+
+  (* Write all arcs *)
+  e_iter graph (fun id1 id2 lbl -> fprintf ff "\t%d -> %d [ label = \"%s\" ];\n" id1 id2 lbl) ;
+
+  fprintf ff "}\n" ;
+
+  close_out ff ;
+  ()

src/gfile.mli

@@ -12,7 +12,7 @@ val from_file: path -> string graph
  * If necessary, use gmap (to be written by you) to prepare the input graph. *)
 val write_file: path -> string graph -> unit
 
-
+val export: path -> string graph -> unit
 
 (* The format of files is compatible with the files generated by:
    https://www-m9.ma.tum.de/graph-algorithms/flow-ford-fulkerson/index_en.html

src/tool.ml

@@ -0,0 +1,15 @@
+(* Yes, we have to repeat open Graph. *)
+open Graph
+
+(* assert false is of type ∀α.α, so the type-checker is happy. *)
+
+
+let clone_nodes gr = n_fold gr new_node empty_graph 
+
+
+(* Clone the nodes first then clone every arc but change their label by applying f*)
+let gmap gr f = 
+  let new_graph = clone_nodes gr in
+  e_fold gr (fun acu id1 id2 x -> new_arc acu id1 id2 (f x)) new_graph 
+
+let add_arc g id1 id2 n = assert false

src/tool.mli

@@ -0,0 +1,9 @@
+open Graph
+
+(* Clone a graph by keeping only its nodes *)
+val clone_nodes: 'a graph -> 'b graph
+
+(* Apply a function f to every label of the graph's arcs *)
+val gmap: 'a graph -> ('a -> 'b) -> 'b graph
+
+val add_arc: int graph -> id -> id -> int -> int graph