包含雙精度值的串列的折線圖表示

我有包含雙型別數字的值串列，每個串列都包含大約 5000 個值。每個串列都是在 60 秒內從微控制器收集的。
我想創建一個折線圖來顯示這些值的方差。我嘗試在 Flutter 中使用樣條圖，但我無法讓它從串列中讀取值，因為它拋出了這個錯誤：

回傳型別“串列？” 不是'num？'，正如閉包的背景關系所要求的那樣。

這是代碼：

 Widget build(BuildContext context) {
    final List<ChartData> chartData = [
      ChartData(10, [5.5,0.6]),
      ChartData(20, [2.5,0.6]),
      ChartData(30, [1.5,0.6]),
      ChartData(40, [0.5,0.6]),
      ChartData(50, [0.5,3.6]),
      ChartData(60, [0.5,2.6]),
      ChartData(70, [0.5,1.6]),
      ChartData(80, [0.5,0.63]),
      ChartData(90, [0.5,0.126]),
    ];
    return Scaffold(
        body: Center(
            child: Container(
                child: SfCartesianChart(
                    series: <ChartSeries>[
                      // Renders spline chart
                      SplineSeries<ChartData, int>(
                          dataSource: chartData,
                          xValueMapper: (ChartData data, _) => data.x,
                          yValueMapper: (ChartData data, _) => data.y
                      )
                    ]
                )
            )
        )
    );
  }
}
class ChartData {
  ChartData(this.x, this.y);
  final int x;
  final List? y;
}

我嘗試創建一個值很少的串列，并將每個串列中的一些元素呼叫到圖表中。它看起來像這樣：

List x =[1.0,1.2,1.3,1.5,1.9,1.8,1.9,2.9,3.9,1.9,1.8,1.4];

  @override
  Widget build(BuildContext context) {
    final List<ChartData> chartData = [
      ChartData(10, x[1]),
      ChartData(20, x[2]),
      ChartData(30, x[0]),
      ChartData(40, x[4]),
      ChartData(50, x[5]),
      ChartData(60, x[6]),
      ChartData(70, x[7]),
      ChartData(80, x[8]),
      ChartData(90, x[9]),
    ];

這對我有用，但我能做到嗎，這樣我就可以將串列中的所有元素呼叫到圖表中。您對如何使這件事發生有任何建議。先感謝您

uj5u.com熱心網友回復：

您y的輸入ChartData是串列。你試著把它分配給num?

yValueMapper: (ChartData data, _) => data.y

如果長度y不固定，可以使用該函式生成SplineSeries

 List<SplineSeries> generateSplineSeries(List<ChartData> chartData){
    List<SplineSeries> splines = [];
    for(int i=0; i<chartData.first.y!.length; i  ){
      splines.add( SplineSeries<ChartData, int>(
        dataSource: chartData,
        xValueMapper: (ChartData data, _) => data.x,
        yValueMapper: (ChartData data, _) => data.y![i],
      ));
    }
    return splines;
  }

Widget build(BuildContext context) {
    final List<ChartData> chartData = [
      ChartData(10, [5.5,0.6]),
      ChartData(20, [2.5,0.6]),
      ChartData(30, [1.5,0.6]),
      ChartData(40, [0.5,0.6]),
      ChartData(50, [0.5,3.6]),
      ChartData(60, [0.5,2.6]),
      ChartData(70, [0.5,1.6]),
      ChartData(80, [0.5,0.63]),
      ChartData(90, [0.5,0.126]),
    ];
    return Scaffold(
        body: Center(
            child: Container(
                child: SfCartesianChart(
                    series: generateSplineSeries(chartData),
                )
            )
        )
    );
  }

uj5u.com熱心網友回復：

@override
  Widget build(BuildContext context) {

    List x =[10.0,1.2,1.3,1.5,1.9,1.8,1.9,2.9,3.9,1.9,1.8,1.4];
    final List<ChartData> chartData = [
      ChartData(60,x),

    ];
    List<SplineSeries> generateSplineSeries(List<ChartData> chartData){
      List<SplineSeries> splines = [];
      for(int i=0; i<chartData.first.y!.length; i  ){
        splines.add( SplineSeries<ChartData, int>(
          dataSource: chartData,
          xValueMapper: (ChartData data, _) => data.x,
          yValueMapper: (ChartData data, _) => data.y![i],
        ));
      }
      return splines;
    }
    return Scaffold(
        body: Center(
            child: Container(
                child: SfCartesianChart(
                    series: generateSplineSeries(chartData),
                )
            )
        )
    );
  }
}
class ChartData {
  ChartData(this.x, this.y);
  final int x;
  final List? y;
}

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