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How to create a StripChart

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Chart (Obsolete)
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Marc
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Marc asked on 20 May 2010, 05:02 PM
I would like to create a dynamic strip chart using RadChart.

Chart type is Line
The x-axis should be a time axis showing the time of the last update

After filling the x-axis I would like to drop the oldest point and add a new point to the end of the chart

This sample code adds the new item to the chart but how would I add x-axis (time) labels for each new item?
           if (Session["rtvals"] == null
            Session["rtvals"] = DateTime.Now.Second; 
            else 
            Session["rtvals"] = Session["rtvals"] + "," + DateTime.Now.Second; 
 
            String[] vals = Session["rtvals"].ToString().Split(','); 
            for (int i = 0; i < vals.Length; i++) 
            { 
                Chart5.Series[0].AddItem(Convert.ToDouble(vals[i])); 
            } 

Thanks

Marc

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Marc
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answered on 20 May 2010, 05:45 PM
I have changed my code to the following:

This code adds the current time to the XVALUE which is incremented by 30 seconds but the chart is
plotting points at the same x-axis time (see attached image).

       Chart5.PlotArea.XAxis.AutoScale = false
            Chart5.PlotArea.YAxis.IsZeroBased = true
 
            if (Session["rtstime"] == null) Session["rtstime"] = DateTime.Now; 
 
            if (Session["rtvals"] == null
            Session["rtvals"] = DateTime.Now.Second; 
            else 
            Session["rtvals"] = Session["rtvals"] + "," + DateTime.Now.Second; 
 
            const double hourStep = 1 / 24.0; 
            const double secondStep = hourStep / 3600; 
            const double thirtysecondStep = secondStep * 30; 
 
            double startTime = Convert.ToDateTime(Session["rtstime"]).ToOADate(); 
            double endTime = DateTime.Now.ToOADate(); 
 
            Chart5.PlotArea.XAxis.AddRange(startTime, endTime, 3600/30); 
            String[] vals = Session["rtvals"].ToString().Split(','); 
            int i=0; 
            for (double currentTime = startTime; currentTime < endTime; currentTime += thirtysecondStep) 
            { 
                ChartSeriesItem item = new ChartSeriesItem(); 
                item.XValue = currentTime; 
                item.YValue = Convert.ToDouble(vals[i]); 
                Chart5.Series[0].Items.Add(item); 
                i++; 
            } 

What am I doing wrong???
0
Ves
Telerik team
answered on 25 May 2010, 12:23 PM
Hello Marc,

The OLEAutomation DateTime equivalent (which is used in RadChart, retrieved by the DateTime.ToOADate method) represents one day as the number one. So this line:
Chart5.PlotArea.XAxis.AddRange(startTime, endTime, 3600/30);
sets a step which is 120 days.  I am not sure if this is the expected setting. In addition, I can see that on initial load, when Session["rtstime"] is not set, the start and end values will be very close or identical -- both are set to DateTime.Now.ToOADate(). Please, check these and let us know if the issue remains.

Best regards,
Ves
the Telerik team

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Ves
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