init

1 files changed, 135 insertions, 0 deletions

diff --git a/src/chart.ml b/src/chart.ml
new file mode 100644
index 0000000..0aee05d
--- /dev/null
+++ b/src/chart.ml
@@ -0,0 +1,135 @@
+exception Empty_list
+let fold fn = function
+    | [] -> raise Empty_list
+    | head :: tail -> List.fold_left fn head tail
+
+let list_min ls = fold Stdlib.min ls
+let list_max ls = fold Stdlib.max ls
+
+let rec repeat n a =
+    if n <= 0
+    then []
+    else a :: repeat (n - 1) a
+
+let empty ls = (ls = [])
+
+let rec zip l1 l2 =
+    match (l1, l2) with
+    | ([], _) -> []
+    | (_, []) -> []
+    | (h1 :: t1, h2 :: t2) -> (h1, h2) :: zip t1 t2
+
+let rec transpose = function
+    | [] :: _ -> []
+    | ls -> List.(map hd ls) :: transpose List.(map tl ls)
+
+let flip f a b = f b a
+
+let rot_right ls = List.(rev ls |> transpose)
+let rot_left ls  = List.(transpose ls |> rev)
+
+let to_string c = String.make 1 c
+let space = to_string ' '
+
+let saturating_sub b a =
+    if a < b then 0
+    else a - b
+
+module type Marker = sig
+    type t
+    val of_string : string -> t
+    val to_string : t -> string
+end
+
+module Marker = struct
+    type t = Point 
+           | Pixel 
+           | Circle 
+           | TriangleDown 
+           | TriangleUp
+           | TriangleLeft
+           | TriangleRight
+           | Custom of string
+
+    exception Invalid_marker_length
+    let of_string s = 
+        if String.length s <> 1
+        then raise Invalid_marker_length
+        else Custom(s)
+
+    let to_string = function
+        | Point -> "."
+        | Pixel -> ","
+        | Circle  -> "o"
+        | TriangleDown  -> "v"
+        | TriangleUp -> "^"
+        | TriangleLeft -> ">"
+        | TriangleRight -> "<"
+        | Custom(s) -> s
+end
+
+module type ChartOptions = sig
+    type t
+    val default : t
+    val with_height  : int -> t -> t
+    val with_marker  : string -> t -> t
+end
+
+module ChartOptions = struct
+    type t = { height: int; ascii: bool; marker: Marker.t}
+    let default =
+        { height = 14
+        ; ascii = false
+        ; marker = Marker.Point
+        }
+    let with_height v c = {c with height = v; }
+    let with_marker v c = {c with marker = v; }
+end
+
+module Chart = struct
+    let draw vals (opts: ChartOptions.t) =
+        let height = opts.height in
+        (* let width = List.length vals in *)
+        let min_val = list_min vals in
+        let max_val = list_max vals in
+        (*let range = max_val - min_val in*)
+
+        (* rescale from min-max to 0-height *)
+        let scale v = ((v - min_val) * height) / max_val in
+        let new_vals = List.map scale vals in
+        let rec pad left right s =
+            if left = 0
+            then s :: repeat right space
+            else space :: pad (left - 1) right s
+        in
+        let new_vals' = zip new_vals (List.tl new_vals) in
+        let make_connector s e =
+            match Stdlib.compare s e with
+            | 0 -> pad s (height - s - 1) "-"
+            | x ->
+                let (ltr_chr, rtl_chr) =
+                    match x with
+                    | 1 -> ("└", "┐")
+                    | _ -> ("┘", "┌")
+                in
+                let (st, en) = Stdlib.((min s e, max s e)) in
+                let l = en - st |> saturating_sub 1 in
+                let (left, right) = (repeat st space, repeat (height - l - st - 1) space)
+                in
+                List.flatten [left; [ltr_chr]; repeat l "│"; [rtl_chr]; right]
+            in
+        let m = Marker.to_string opts.marker in
+        let rec make_graph = function
+            | [] -> []
+            | (s, e) :: [] ->
+                    pad s (height - s - 1) m
+                    :: make_connector s e
+                    :: pad e (height - e - 1) m
+                    :: []
+            | (s, e) :: tl ->
+                    pad s (height - s - 1) m
+                    :: make_connector s e 
+                    :: make_graph tl
+        in
+        make_graph new_vals' |> rot_left
+end