Trendline with Snap to Point & Semi log Aware Trendline

[Christopher]

Hello,

*Line is converted to log curve *
http://www.youtube.com/watch?v=y55VmSIMBjE

for mathematical formula use below link
https://en.wikipedia.org/wiki/Semi-log_plot

Thank you.

Semi-log plots are perfectly feasible in TeeChart, e.g.

Code: Select all

    Line series;
    
    private void InitializeChart()
    {
      tChart1.Aspect.View3D = false;
      series = new Line(tChart1.Chart);
      series.Add(9, 25112);
      series.Add(12, 12223);
      series.Add(14, 9216);
      series.Add(16, 7488);
      series.Add(21, 4889);

      tChart1.Axes.Left.Logarithmic = true;
      tChart1.Axes.Left.Increment = 5000;
      tChart1.Axes.Left.SetMinMax(2000, 40000);
      tChart1.Axes.Bottom.SetMinMax(5, 25);
    }

Trendlines and other TeeChart functions can also be used in semi-log plots, e.g.

Code: Select all

    Line series, func;
    
    private void InitializeChart()
    {
      tChart1.Aspect.View3D = false;
      series = new Line(tChart1.Chart);
      series.Add(9, 25112);
      series.Add(12, 12223);
      series.Add(14, 9216);
      series.Add(16, 7488);
      series.Add(21, 4889);

      tChart1.Axes.Left.Logarithmic = true;
      tChart1.Axes.Left.Increment = 5000;
      tChart1.Axes.Left.SetMinMax(2000, 40000);
      tChart1.Axes.Bottom.SetMinMax(5, 25);

      func = new Line(tChart1.Chart);

      TrendFunction trend = new TrendFunction();
      trend.TrendStyle = TrendStyles.Exponential;
      func.Function = trend;
      func.DataSource = series;
    }

of the video you link to, which functionality do you need which is present in Excel but which you cannot find in TeeChart?

[Quant]

I am using drawline tool. I cant use series as use is drawing line as per his requirement. how to make semi log lines drawn by drawline

[Christopher]

Hello,

how to make semi log lines drawn by drawline

I'm sorry, but I don't understand this request. The DrawLine tool is designed to draw a line between two points defined by mouse clicks. This tool works as expected in semi-log charts.

[Quant]

1) I am using drawline tool to draw a line on normal scale.
2) when i convert normal scale to semilog
3) all series got converted to semilog except the line drawn with drawline tool.
4) I want to convert this line which is drawn by drawline tool to semilog.

[Christopher]

1) I am using drawline tool to draw a line on normal scale.
2) when i convert normal scale to semilog
3) all series got converted to semilog except the line drawn with drawline tool.
4) I want to convert this line which is drawn by drawline tool to semilog.

The following code does all of the above:

Code: Select all

    Line series;
    DrawLine tool;

    private void InitializeChart()
    {
      tChart1.Aspect.View3D = false;
      series = new Line(tChart1.Chart);
      series.Add(9, 25112);
      series.Add(12, 12223);
      series.Add(14, 9216);
      series.Add(16, 7488);
      series.Add(21, 4889);

      tChart1.Axes.Left.SetMinMax(2000, 40000);
      tChart1.Axes.Bottom.SetMinMax(5, 25);

      tool = new DrawLine(tChart1.Chart);

      tChart1.Draw();

      DrawLineItem line = new DrawLineItem(tool);
      line.StartPos = new PointDouble(9, 25112);
      line.EndPos = new PointDouble(21, 4889);
      tool.Lines.Add(line);

    }


    private void button4_Click(object sender, EventArgs e)
    {
      tChart1.Axes.Left.Logarithmic = true;
      tChart1.Axes.Left.Increment = 5000;
    }

[Quant]

we dont want predefined series. we want user to draw line same as drawing with drawline tool.

[Christopher]

we dont want predefined series. we want user to draw line same as drawing with drawline tool.

I'm afraid I don't understand what you mean here. Could you please try and be a little more specific with the use of code examples I can run here, images and videos?

[Marc]

Hello,

we dont want predefined series. we want user to draw line same as drawing with drawline tool.

Drawline tool may be used in normal manner. Code values will be updated according to any Axis visualisation changes. DrawLine co-ordinates can be updated at any time by customer code.

Regards,
Marc Meumann

[Quant]

Hi,

We are starting this discussion again to discuss "Semi-Log Trendline" in more detail, thereby we can help each other to solve this requirement.

Note: Following steps are based on usage of "Semi-Log Trendline" from a popular charting software.

Step 1] Consider a chart (OHLC with Candle Line) with Right Axis Semi Log Scaled as shown in below screenshot (Screen 1).

Screen 1

SL1.jpg (104.55 KiB) Viewed 22032 times

Step 2] Now a User Draws a "Semi-Log Trendline" on a Chart by using "Semi-Log Trendline" Tool as shown in below Screenshot (Screeen 2).
As shown in "Screen 2" it shows straight line drawn on semi log scaled chart.

Screen 2

SL2.jpg (108.21 KiB) Viewed 22030 times

Step 3] When user changes Semi log scale to Arithmetic scale, then previously drawn straight line becomes a curved line as shown in below screenshot (Screen 3).

Screen 3

SL3.jpg (105.02 KiB) Viewed 22025 times

Above three steps comprises of Semi Log Trendline working.

[Christopher]

Above three steps comprises of Semi Log Trendline working.

Here it is working in TeeChart:

Code: Select all

    Line series;
    DrawLine tool;

    private void InitializeChart()
    {
      tChart1.Aspect.View3D = false;
      series = new Line(tChart1.Chart);
      series.Add(9, 25112);
      series.Add(12, 12223);
      series.Add(14, 9216);
      series.Add(16, 7488);
      series.Add(21, 4889);

      tChart1.Axes.Left.SetMinMax(2000, 40000);
      tChart1.Axes.Bottom.SetMinMax(5, 25);

      tChart1.Axes.Left.Logarithmic = true;
      tChart1.Axes.Left.Increment = 5000;

      tool = new DrawLine(tChart1.Chart);

      DrawLineItem line = new DrawLineItem(tool);
      line.StartPos = new PointDouble(9, 25112);
      line.EndPos = new PointDouble(21, 4889);
      tool.Lines.Add(line);

    }

    private List<PointDouble> CalcCurve()
    {
      List<PointDouble> result = new List<PointDouble>();

      Point start = new Point(tChart1.Axes.Bottom.CalcXPosValue(tool.Lines[0].StartPos.X), tChart1.Axes.Left.CalcYPosValue(tool.Lines[0].StartPos.Y));
      Point end = new Point(tChart1.Axes.Bottom.CalcXPosValue(tool.Lines[0].EndPos.X), tChart1.Axes.Left.CalcYPosValue(tool.Lines[0].EndPos.Y));
      double dxdy = (double)Math.Abs(start.X - end.X) / (double)Math.Abs(start.Y - end.Y);

      int count = 0;

      for (int i = start.Y; i <= end.Y; i++)
      {
        result.Add(new PointDouble(tChart1.Axes.Bottom.CalcPosPoint(start.X + Utils.Round(count * dxdy)), tChart1.Axes.Left.CalcPosPoint(i)));
        count++;
      }

      return result;
    }

    private void button4_Click(object sender, EventArgs e)
    {
      if(tChart1.Axes.Left.Logarithmic)
      {
        List<PointDouble> list = CalcCurve();
        Line newLine = new Line(tChart1.Chart);
        newLine.Color = Color.Black;
        newLine.Legend.Visible = false;
        tChart1.Legend.LegendStyle = LegendStyles.Values;
        foreach (var item in list)
        {
          newLine.Add(item.X, item.Y);
        }
        tool.Active = false;
      }
      else
      {
        if(tChart1.Series.Count > 1)
        {
          tChart1.Series.RemoveAt(1);
        }
        tool.Active = true;
      }

      tChart1.Axes.Left.Logarithmic = !tChart1.Axes.Left.Logarithmic;
    }

Step 1:

export635917393165277370.png (23.04 KiB) Viewed 22009 times

Step 2:

export635917393212439633.png (21.26 KiB) Viewed 22008 times

This is just a proof of concept that TeeChart is capable of rendering this change from [straight line in log] -> [curve in non-log] ... the actual implementation of this in your context may be a little different.

[Quant]

Thanks for the reply. Yes sample code is working as per the same concept.

But how can we draw semi log trend line vice versa i.e. [curve in non-log] --> [straight line in log]. Could you please provide the sample code for the same?

[Christopher]

But how can we draw semi log trend line vice versa i.e. [curve in non-log] --> [straight line in log]. Could you please provide the sample code for the same?

Again, I'm not sure about your requirements here, but the code I sent you can be engineered to work in reverse so that it draws the "log curve" in the non-log plot and vice-versa. I'm afraid I don't have the time at the moment to actually write the code for you.