c# - 存在空点时如何继续图表？

Question

using System.Web.UI.DataVisualization.Charting.Chart

我的数据是这样的:

...但是我的图表没有在缺失数据点之间画线:

如您所见，第 2 列在 2015 年 7 月 9 日的 51 处有一个点，然后点在 2015 年 7 月 16 日之前都是空的。我希望图表从 7/09/2015 到 7/16/2015 绘制一条线。

我怎样才能让它发挥作用？

这是我现有的 Series build :

var series = chart.Series[header] = new Series(header) {
    BorderWidth = 2,
    ChartArea = DataTable.TableName,
    ChartType = SeriesChartType.FastLine,
    Color = legendColors[header],
    Enabled = true,
    Font = new Font("Lucida Sans Unicode", 6f),
    XValueMember = "Week",
    YValueMembers = header
};

更新 1:
有了@jstreet 的回答，我现在画了一条线。但是该值被表示为 0:

预期的是以下粗虚线应替换代表值 0 的线:

更新 2:
修改了for-loop手动添加 DataPoint s 到 series按照@jstreet 在代码隐藏 中添加点的示例:

for (int column = 0; column < seriesHeaders.Length; column++) {
    var header = seriesHeaders[column];

    var series = chart.Series[header] = new Series(header) {
        BorderWidth = 2,
        ChartArea = DataTable.TableName,
        ChartType = SeriesChartType.FastLine,
        Color = legendColors[header],
        Enabled = true,
        Font = new Font("Lucida Sans Unicode", 6f),
        XValueMember = "Week",
        YValueMembers = header
    };
    series.EmptyPointStyle.Color = legendColors[header];
    series.EmptyPointStyle.AxisLabel = "Empty";

    DataTable.Rows
        .OfType<DataRow>()
        .Select(r => (double)r[header])
        .ToList()
        .ForEach(v => {
            series.Points.Add(new DataPoint(series) {
                IsEmpty = v == Double.NaN,
                YValues = new double[] { v == Double.NaN ? 0 : v }
            });
        });

}

...图表仍将本应为空点的点呈现为 0。值(value)。

更新 3:
DataPoint的修改结构|秒。显然v == Double.NaN没有正确评估:

DataTable.Rows
    .OfType<DataRow>()
    .Select(r => (double)r[header])
    .ToList()
    .ForEach(v => {
        var isEmpty = Double.IsNaN(v);
        var value = new double[] { v == Double.NaN ? 0 : v };

        series.Points.Add(new DataPoint() {
            IsEmpty = isEmpty,
            YValues = value
        });
    });

... 我验证了 Series.Points收藏:

Answer 1

需要定义一个EmptyPointStyle，如下图:

            <asp:Series Name="Series1" ChartType="Line" XValueType="DateTime">
                <Points>
                    <asp:DataPoint XValue="42005" YValues="50" />
                    <asp:DataPoint XValue="42036" YValues="70" />
                    <asp:DataPoint XValue="42064" YValues="30" />
                    <asp:DataPoint IsEmpty="True" XValue="42095" YValues="0" />
                    <asp:DataPoint XValue="42156" YValues="60" />
                    <asp:DataPoint XValue="42186" YValues="40" />
                </Points>
                <EmptyPointStyle Color="Red" />
            </asp:Series>

结果:

编辑:我还可以使用隐藏代码添加点数:

    protected void Page_Load(object sender, EventArgs e)
    {
        Chart1.Series[0].Points.Add(new DataPoint { IsEmpty = false, XValue = DateTime.Now.AddDays(1).ToOADate(), YValues = new double[] { 50 } });
        Chart1.Series[0].Points.Add(new DataPoint { IsEmpty = false, XValue = DateTime.Now.AddDays(2).ToOADate(), YValues = new double[] { 70 } });
        Chart1.Series[0].Points.Add(new DataPoint { IsEmpty = true, XValue = DateTime.Now.AddDays(3).ToOADate(), YValues = new double[] { 0 } });
        Chart1.Series[0].Points.Add(new DataPoint { IsEmpty = false, XValue = DateTime.Now.AddDays(4).ToOADate(), YValues = new double[] { 30 } });
        Chart1.Series[0].Points.Add(new DataPoint { IsEmpty = false, XValue = DateTime.Now.AddDays(5).ToOADate(), YValues = new double[] { 60 } });
    }

我没有遇到您描述的无法设置 IsEmpty 或在图表中获取 0 的问题: