從可縮放圖C＃的計算＃

Question

基本上我有一個圖表綁定從一個DataTable哪個來源是從DataGridView。我在圖上有可縮放的函數，我需要它使用X Axis SelectionStart和SelectionEnd來計算所選數據塊。

所以我有一些最小值最大值和平均值放在另一個選項卡上的richtextbox。如代碼如下所示：在圖像中

//To show the Data from file into the TextBox               
     richTextBox1.AppendText("\n" + "Heart Average : " + HRM.Active.DataRows.Average(r => r.HeartRate) + "\n"); 
     richTextBox1.AppendText("\n" + "Heart Minimum : " + HRM.Active.DataRows.Min(r => r.HeartRate) + "\n"); 
     richTextBox1.AppendText("\n" + "Heart Maximum : " + HRM.Active.DataRows.Max(r => r.HeartRate) + "\n"); 
     richTextBox1.AppendText("\n" + "Average Speed (KM/H): " + HRM.Active.DataRows.Average(r => r.Speed) + "\n"); 
     richTextBox1.AppendText("\n" + "Maximum Speed : " + HRM.Active.DataRows.Max(r => r.Speed) + "\n"); 
     richTextBox1.AppendText(Environment.NewLine + " - (MPH): " + ""); 
     richTextBox1.AppendText("\n" + "Average Power: " + HRM.Active.DataRows.Average(r => r.Power) + "\n"); 
     richTextBox1.AppendText("\n" + "Maximum Power : " + HRM.Active.DataRows.Max(r => r.Power) + "\n"); 
     richTextBox1.AppendText("\n" + "Average Altitude (KM/H): " + HRM.Active.DataRows.Average(r => r.Altitude) + "\n"); 
     richTextBox1.AppendText("\n" + "Maximum Altitude : " + HRM.Active.DataRows.Max(r => r.Altitude) + "\n"); 
     richTextBox1.AppendText("\n" + "Cadence Average : " + HRM.Active.DataRows.Average(r => r.Cadence) + "\n"); 
     richTextBox1.AppendText("\n" + "Cadence Maximum : " + HRM.Active.DataRows.Max(r => r.Cadence) + "\n"); 
     richTextBox1.AppendText("\n" + "Pressure Average : " + HRM.Active.DataRows.Average(r => r.Pressure) + "\n"); 
     richTextBox1.AppendText("\n" + "Pressure Maximum : " + HRM.Active.DataRows.Max(r => r.Pressure) + "\n"); 

現在下面你可以看到圖，它顯示在那裏的數據的圖像，這裏是結合所述數據表的曲線圖的代碼。

protected void drawChart() 
    { 
     DataTable dt = new DataTable(); 
     dt.Clear(); 
     foreach (DataGridViewColumn col in dataGridView1.Columns) 
     { 
      dt.Columns.Add(col.HeaderText); 
     } 
     foreach (DataGridViewRow row in dataGridView1.Rows) 
     { 
      DataRow dRow = dt.NewRow(); 
      foreach (DataGridViewCell cell in row.Cells) 
      { 
       dRow[cell.ColumnIndex] = cell.Value; 
      } 
      dt.Rows.Add(dRow); 
     } 

現在我需要做的是每次我放大時間附近的另一圖形和文本框和灰塊出來它顯示我所選擇的塊中的最小值maximiums和均線！然後，當我縮小它重置爲原來的。

如果你不明白我的意思只是給我發消息，我會提供更多信息。

Answer 1

要縮放或滾動後更新基於可視Points統計計算，你需要知道兩件事情：當你應該這樣做，並指向可見。

要使用的事件是AxisViewChanged，那很容易。你已經迷上它後，你可以調用一個函數來更新你的統計：

private void chart1_AxisViewChanged(object sender, ViewEventArgs e) 
{ 
    updateStats(); 
} 

困難的部分是要知道哪些Points收集部分可見。

乍一看你可能認爲ViewEventArgs帕爾姆有幫助;畢竟它有如下有前途的數據：NewPosition和NewSize。

但仔細看，你會發現兩者都是雙打的，所以除非你的XValues已經從0開始計數爲1，它們將不會索引到Points集合中。

相反，我們必須對這些值進行一些搜索，從左到右和最右側。這裏有一個功能可以這樣做：

int getVisiblePoint(Chart chart, Series series, bool first) 
{ 
    Series S = series; 
    ChartArea CA = chart.ChartAreas[S.ChartArea]; 
    DataPoint pt = null; 
    if (first) pt = S.Points.Select(x => x) 
           .Where(x => x.XValue >= CA.AxisX.ScaleView.ViewMinimum) 
           .DefaultIfEmpty(S.Points.First()).First(); 
    else pt = S.Points.Select(x => x) 
         .Where(x => x.XValue <= CA.AxisX.ScaleView.ViewMaximum) 
         .DefaultIfEmpty(S.Points.Last()).Last(); 

    return S.Points.IndexOf(pt); 
} 

從這裏開始事情變得容易多了;使用簡單的功能做數學

void updateStats() 
{ 
    int firstPt = getVisiblePoint(chart1, chart1.Series[0], true); 
    int lastPt = getVisiblePoint(chart1, chart1.Series[0], false); 
    int sCount = chart1.Series.Count; 
    double[] avg = new double[sCount]; 
    double[] min = new double[sCount]; 
    double[] max = new double[sCount]; 

    for (int i = 0; i < sCount; i++) 
    { 
     Series S = chart1.Series[i]; 
     avg[i] = getAverage(S, firstPt, lastPt); 
     min[i] = getMixMax(S, firstPt, lastPt, true); 
     max[i] = getMixMax(S, firstPt, lastPt, false); 
    } 
    // insert code to display the data here! 
} 

：

double getAverage(Series series, int first, int last) 
{ 
    double sum = 0; 
    for (int i = first; i < last; i++) sum += series.Points[i].YValues[0]; 
    return sum/(last - first + 1); 
} 

double getMixMax(Series series, int first, int last, bool min) 
{ 
    double val = 0; 

    for (int i = first; i < last; i++) 
    { 
     double v = series.Points[i].YValues[0]; 
     if ((min && val > v) || (!min && val >= v)) val = v; 
    } 
    return val; 
}