Visual Basic WinForms Spline Chart缺失值引发蓝色竖线问题求助

问题根源是代码未处理CSV中的缺失/无效数据，当遇到无法解析为数值的speed字段时，要么触发异常，要么错误生成无效数据点，最终导致Spline曲线连接时出现竖线。以下是两种可行的修复方案：

方案一：跳过无效数据行 #

解析前先校验数据有效性，直接跳过无法解析的行：

Dim openFileDialog1 As New OpenFileDialog With {
    .Filter = "CSV files (*.csv)|*.csv",
    .FilterIndex = 1,
    .Multiselect = True,
    .Title = "Select only CSV files"
}

If openFileDialog1.ShowDialog() = DialogResult.OK Then
    Chart1.Visible = True
    If Chart1.Series.Count > 0 Then
        Chart1.Series.Clear()
    End If

    Dim fileCounter As Integer = 0

    For Each file As String In openFileDialog1.FileNames
        fileCounter += 1
        Dim lineCounter As Integer = 0
        ' 使用Using自动释放StreamReader资源，替代手动Close
        Using sr As New StreamReader(file)
            Dim currentLine As String

            While sr.Peek() >= 0
                currentLine = sr.ReadLine()
                lineCounter += 1

                If lineCounter = 1 Then
                    Dim series As New Series With {
                        .Name = Path.GetFileNameWithoutExtension(file),
                        .ChartType = SeriesChartType.Spline,
                        .IsXValueIndexed = True ' 启用X值索引，避免X轴间隔异常
                    }
                    Chart1.Series.Add(series)
                Else
                    Dim values() As String = currentLine.Split(",")
                    ' 校验数据长度和字段有效性
                    If values.Length >= 2 AndAlso Not String.IsNullOrWhiteSpace(values(1)) Then
                        Dim speed As Double
                        If Double.TryParse(values(1), speed) Then
                            Dim timers As String = values(0)
                            Chart1.Series(fileCounter - 1).Points.AddXY(timers, speed)
                        End If
                    End If
                End If
            End While
        End Using
    Next
End If

方案二：标记空值点（保留X轴位置但不绘制） #

如果需要保留缺失值对应的X轴位置，可将无效点标记为空，Chart会自动跳过这些点的连接：

Dim openFileDialog1 As New OpenFileDialog With {
    .Filter = "CSV files (*.csv)|*.csv",
    .FilterIndex = 1,
    .Multiselect = True,
    .Title = "Select only CSV files"
}

If openFileDialog1.ShowDialog() = DialogResult.OK Then
    Chart1.Visible = True
    If Chart1.Series.Count > 0 Then
        Chart1.Series.Clear()
    End If

    Dim fileCounter As Integer = 0

    For Each file As String In openFileDialog1.FileNames
        fileCounter += 1
        Dim lineCounter As Integer = 0
        Using sr As New StreamReader(file)
            Dim currentLine As String

            While sr.Peek() >= 0
                currentLine = sr.ReadLine()
                lineCounter += 1

                If lineCounter = 1 Then
                    Dim series As New Series With {
                        .Name = Path.GetFileNameWithoutExtension(file),
                        .ChartType = SeriesChartType.Spline,
                        .IsXValueIndexed = True
                    }
                    Chart1.Series.Add(series)
                Else
                    Dim values() As String = currentLine.Split(",")
                    Dim timers As String = values(0)
                    Dim dp As New DataPoint()
                    dp.AxisLabel = timers

                    If values.Length >= 2 AndAlso Not String.IsNullOrWhiteSpace(values(1)) AndAlso Double.TryParse(values(1), dp.YValues(0)) Then
                        ' 有效数据，正常保留
                    Else
                        ' 标记为空点，Chart将跳过该点的绘制与连接
                        dp.IsEmpty = True
                    End If

                    Chart1.Series(fileCounter - 1).Points.Add(dp)
                End If
            End While
        End Using
    Next
End If

核心优化说明 #

• 用Double.TryParse替代Double.Parse，避免解析失败抛出异常
• 启用Series.IsXValueIndexed = True，让Chart按数据点顺序排列X轴，避免因X值间隔异常导致的竖线
• 使用Using语句管理流资源，比手动调用Close更安全可靠

内容的提问来源于stack exchange，提问作者smal