Question

拥有此代码：

let errorChanged = new Event<(int * float)>()

let learn error data w w_ iter =
    let rec learning error data w w_ i icount =
        //recursive(loop) fire event
        errorChanged.Trigger(i, e) //trigger event for chart update
        if (/**/) then
            learning /*params*/
        else
            /*do else*/

    let plot = LiveChart.PointIncremental(errorChanged.Publish |> Event.every 5)
    plot.ShowChart()
    learning error data w w_ 0 iter

当我运行它时，我会看到点图表窗口，它没有响应（而不是更新）。根据{{3}}，这应该运作良好，但...... 我该如何解决这个问题？

UPD ：

如果我这样做：

let rec learning error data w w_ i icount = async {
            let e = Seq.fold (fun s x ->
                                         s + errorPart w w_ x x) 0.0 data
            errorChanged.Trigger(i, e)
            if (e > error && i <= iter) then
                printfn "[iter] = %d of %d. [e] = %f" i icount e
                let (w, w_) = Seq.fold (fun (w, w_) x -> 
                                                learnPart w w_ x x) (w, w_) data
                return! learning error data (normalize w) (normalize w_) (i + 1) icount
            else
                let resultData = Seq.map (fun x -> calculatePart w w_ x) data
                let y = resultData
                        |> Seq.map (fun (y, _) -> y) 
                        |> Seq.concat
                let x_ = resultData
                        |> Seq.map (fun (_, x_) -> x_) 
                        |> Seq.concat
                return (w, w_, e, y, x_) }

        let plot = LiveChart.PointIncremental(errorChanged.Publish |> Event.every 5)
        plot.ShowChart()
        async { return! learning error data w w_ 0 iter}
        |> Async.RunSynchronously

我得到异常：跨线程操作无效。好像我需要像Dispatcher这样的东西。

Answer 1

你的代码片段的问题在于它创建了图表，但它在当前线程上运行learning函数，因此它阻塞了主线程（它永远不会有机会更新图表）。

您可以将learning功能包装在async { .. }块中，然后使用Async.Start运行它。然后它将在后台运行，图表将能够更新。

你没有发布完整的代码，所以我无法测试，但我认为以下内容应该有效：

let rec learning error data w w_ i icount = async { // Async block here!
    (* omitted *)
    errorChanged.Trigger(i, e) //trigger event for chart update
    if (e > error && i <= iter) then
        (* omitted *) 
        // Here, we now need to run the recursive call using 'return!' of async
        return! learning error data (normalize w) (normalize w_) (i + 1) icount
    else
        (* omitted *)
        return (w, w_, e, y, x_) }

let plot = LiveChart.PointIncremental(errorChanged.Publish |> Event.every 5)
plot.ShowChart()

// Create workflow that will run 'learning' and then print the result
// (this needs to return unit, so that we can use 'Async.Start')
async { let! res = learning error data w w_ 0 iter 
        printfn "Finished: %A" res } 
|> Async.Start

Answer 2

它可能缺少WinForms event loop。

尝试使用这个简单的代码来查看它是否先挂起，然后将其应用到您的情节

use form = new Form(Width=400, Height=300, Visible=true, Text="Hello charting")
Chart.Line([for x in 0 ..10 -> x, x+x]).ShowChart()
System.Windows.Forms.Application.Run(form)

图表（Fsharp.Charting）没有回复

2 个答案: