add Dendrogramm

src/BioFSharp.Visualization/PlotlyExtensions/ChartExtensions.fs

@@ -77,3 +77,109 @@ module ChartExtensions =
             |> Chart.withShapes(legendShapes, Append=true)
 
 
+    open Plotly.NET.LayoutObjects
+    open FSharp.Stats.ML.Unsupervised.HierarchicalClustering
+
+    type Chart with
+
+        /// <summary>
+        /// Build a dendrogram from an FSharp.Stats Cluster&lt;'T&gt;.
+        /// toLabel converts your leaf tag to a label string (e.g. id -> name).
+        /// Use MonotoneHeights=true if your node 'dist' is a merge height; set false if it's a branch length.
+        /// </summary>
+        static member Dendrogram
+            (
+                tree: Cluster<'T>,
+                toLabel: 'T -> string,
+                ?MonotoneHeights: bool,
+                ?LeafTextAngle: float
+            ) =
+
+            // options with sensible defaults to match repo style
+            let monotone     = defaultArg MonotoneHeights true
+            let leafAngle    = defaultArg LeafTextAngle -90.0
+
+            // 1) Left-to-right leaf order
+            let rec leaves = function
+                | Leaf(id,_,tag)      -> [id, tag]
+                | Node(_,_,_,l,r) -> leaves l @ leaves r
+            let orderedLeaves = leaves tree
+
+            // 2) Assign x positions to leaves (0,1,2,...) and map by leaf id
+            let idToX =
+                orderedLeaves
+                |> List.mapi (fun i (id,_) -> id, float i)
+                |> Map.ofList
+
+            // 3) Layout: compute segment list; optionally enforce monotone heights
+            let rec layout = function
+                | Leaf(id,_,_) ->
+                    let x = idToX.[id]
+                    x, 0.0, []
+                | Node(_, dist, _, l, r) ->
+                    let xL, yL, segL = layout l
+                    let xR, yR, segR = layout r
+
+                    // If 'dist' is merge height, keep monotone; if it's a branch length, add.
+                    let yN =
+                        if monotone then max dist (max yL yR)
+                        else max yL yR + dist
+
+                    let segs =
+                        [ ((xL, yL), (xL, yN))
+                          ((xR, yR), (xR, yN))
+                          ((xL, yN), (xR, yN)) ]
+
+                    let xC = (xL + xR) / 2.0
+                    xC, yN, segL @ segR @ segs
+
+            let _,_,segments = layout tree
+
+            // 4) One line trace; use NaNs to break segments
+            let xs =
+                segments
+                |> List.collect (fun ((x1,_),(x2,_)) -> [x1; x2; System.Double.NaN])
+            let ys =
+                segments
+                |> List.collect (fun ((_,y1),(_,y2)) -> [y1; y2; System.Double.NaN])
+
+            let branches =
+                Chart.Scatter(
+                    x = xs,
+                    y = ys,
+                    mode = StyleParam.Mode.Lines,
+                    Name = "branches"
+                )
+                |> Chart.withLine (Line.init())
+
+            // 5) Leaf labels at y=0, rotated
+            let leafXs    = orderedLeaves |> List.map (fun (id,_) -> idToX.[id])
+            let leafTexts = orderedLeaves |> List.map (fun (_,tag) -> toLabel tag)
+
+            let annos =
+                [ for x, txt in List.zip leafXs leafTexts ->
+                    Annotation.init(
+                        X = x, Y = 0.0, Text = txt,
+                        YAnchor = StyleParam.YAnchorPosition.Top,
+                        TextAngle = leafAngle,
+                        ShowArrow = false
+                    ) ]
+
+            // Pad the y-range a bit
+            let maxY =
+                segments
+                |> List.collect (fun ((_,y1),(_,y2)) -> [y1; y2])
+                |> List.fold (fun m v -> if v > m then v else m) 0.0
+
+            [ branches ]
+            |> Chart.combine
+            |> Chart.withAnnotations annos
+            |> Chart.withYAxisStyle(MinMax = (0.0, maxY * 1.05))
+            |> Chart.withXAxis(
+                LinearAxis.init(
+                    ShowTickLabels = false,
+                    Ticks = StyleParam.TickOptions.Empty,
+                    ShowGrid = false,
+                    ZeroLine = false
+                )
+            )