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Hide labels on series which have value of zero, in a chart.

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panchooo
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panchooo asked on 24 May 2010, 10:57 PM
Hello,

I'm currently working with telerik reporting, and I'm displaying a chart for every row of the datasource of the report.
The chart displays a stacked bar chart type. I have a very similar issue like this post:

The difference is that I'm using a report to display the chart, and since I'm in the environment of the report the chart control have only 4 events in which the ItemDataBoundItem, the code I wrote seems to have no visual effect over the chart:

Private Sub chtDefectsByFamily_ItemDataBound(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles chtDefectsByFamily.ItemDataBound 
        Dim ChartItem As Telerik.Reporting.Processing.Chart = DirectCast(sender, Telerik.Reporting.Processing.Chart) 
        Dim ci As Telerik.Reporting.Chart = TryCast(ChartItem.ItemDefinition, Telerik.Reporting.Chart) 
        For Each seriesItem As Telerik.Reporting.Charting.ChartSeries In ci.Series 
            seriesItem.Appearance.LabelAppearance.LabelLocation = Charting.Styles.StyleSeriesItemLabel.ItemLabelLocation.Inside 
            seriesItem.Appearance.TextAppearance.TextProperties.Color = Color.White 
            For Each serieItem As Telerik.Reporting.Charting.ChartSeriesItem In seriesItem.Items 
                If serieItem.YValue = 0 Then 
                    serieItem.Label.Visible = False 
                End If 
                serieItem.SetDirty() 
            Next 
            seriesItem.SetDirty() 
        Next 
    End Sub 

Is it possible to modify the chart during/after the binding of the data?? or is there any other way to hide the labels before the chart is shown?

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Peter
Telerik team
answered on 27 May 2010, 05:24 PM
Hello panchooo,

As you have noticed the Telerik Reporting Chart is quite different. From your explanation I understand that you are using the Chart's Datasource property to set a datasource, that leads to automatic creation of Chart Series. Those automatically created series can't be modified from events.

Our suggestion would be to use the Chart's NeedDataSource event to manually create and populate the Series.
Check out the following help articles:

Data Binding Chart to a Database Object

Sincerely yours, Peter
the Telerik team

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Deepak Shakya
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answered on 31 Jan 2011, 03:20 AM
Hi Peter,

I have a same issue as panchooo and here is what I did in the NeedDataSource event handler.
  • I am using Q3 2010 Release
  • I created a DataTable and populated it using SQL query
  • Assigned the datatable as DataSource to the chart
  • Created ChartSeries and added to the ItemDefinition of the chart
The chart displays fine except for the labels that displays the zero. I added this code to hide the labels:
                        chartDef.Series.Clear();
            chartDef.Series.Add(mySeries);
 
            foreach (ChartSeriesItem myitem in chartDef.Series[0].Items)
            {
                if (myitem.YValue == 0)
                {
                    myitem.Label.Visible = false;
                }
            }

Result:
  • I still see the zeros in the label.
I also checked if it can actually read the series. As a test, I can display the series count in a label but cannot display any of the SeriesItemYvalue. It just returns zero.

UPDATED:

I moved the "foreach" loop into ItemDataBound event of the chart. While stepping through the code, I can see the YValues and the test if the value is zero being carried out. It even steps into set the visible property to false. But the final output still shows the label with 0.0.

Am I missing a statement to update the view? If yes, could you please let me know what it is?

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Peter
Telerik team
answered on 01 Feb 2011, 05:45 PM
Hello Deepak Shakya,

Based on your explanation I understand that you are using the Chart's Datasource property to set a datasource, that leads to automatic creation of Chart Series. Those automatically created series can't be modified from events. Thus our suggestion is to create your chart programmatically as elaborated in the Creating Chart Programmatically help article.

Best wishes,
Peter
the Telerik team
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Deepak Shakya
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answered on 02 Feb 2011, 03:51 AM

Hi Peter,

Thanks for your reply. So are you saying that because I used the Datasource property of the Chart in the NeedDataSource event, I can't change the series programmatically?

  • Could you please send me an example as to how I can populate the series using the queried data or simply a DataTable?

  • The link you provided to create the chart programatically only show how you actually hard code the data in the series. How do I transverse through the table to make up a series of data for the chart?
  •  The example also does not show how to assign the "DataLabelsColumn". How do we do this without setting the "DataSource" property in the chart?
  • I am able to show/hide the labels completely from NeedDataSource event. Its just that I can't do it for individual items in the series.

  • I created a chart in Designer to get the positioning correct. Do I have to create the chart programmatically to be able to show/hide the labels for individual items? It would be great if I didn't have to do this.

Your help is highly appreciated. Thanking you in advance.

 

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Deepak Shakya
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answered on 03 Feb 2011, 06:49 AM
Hi Peter,
  • Just wanted to let you know that I have solved the problem by generating the Chart programatically instead of using the DataSource property.
  • I have also been able to generate X-Axis Labels programmatically
  • //Print X-Axis Labels
                for (int j = 0; j < myDataset.Tables[0].Columns.Count; j++)
                {
                    if (myDataset.Tables[0].Columns[j].ColumnName == "fldShortName")
                    {
     
                        for (int i = 0; i < myDataset.Tables[0].Rows.Count; i++)
                        {
                            ChartAxisItem axisItem = new ChartAxisItem(myDataset.Tables[0].Rows[i][j].ToString());
                            chartDef.PlotArea.XAxis.AddItem(axisItem);
                        }
                        break;
                    }
                }
  • I also generated the series programmatically and hide zero value labels.
  • //Generate Series Bar Graph
                for (int j = 0; j < myDataset.Tables[0].Columns.Count; j++)
                {
                    if (myDataset.Tables[0].Columns[j].ColumnName == "fldData")
                    {
                        ChartSeries nSeries = new ChartSeries("Data", ChartSeriesType.Bar);
                        for (int i = 0; i < myDataset.Tables[0].Rows.Count; i++)
                        {
                            double _value;
                            double.TryParse(myDataset.Tables[0].Rows[i][j].ToString(), out _value);
                            ChartSeriesItem myItem = new ChartSeriesItem(_value);
                            if (_value == 0)
                            {
                                myItem.Label.Visible = false;
                            }
                            nSeries.AddItem(myItem);
                        }
     
                        nSeries.Appearance.EmptyValue.Mode = Telerik.Reporting.Charting.Styles.EmtyValuesMode.Zero;
                        nSeries.Appearance.Corners.TopRight = Telerik.Reporting.Charting.Styles.CornerType.Round;
                        nSeries.Appearance.Corners.TopLeft = Telerik.Reporting.Charting.Styles.CornerType.Round;
                        nSeries.DefaultLabelValue = "#Y{N1}";
                        nSeries.Appearance.BarWidthPercent = 50;
                        chartDef.Series.Add(nSeries);
                        break;
                    }
                }
  • Thank you once again for viewing this entry.
 
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Deepak Shakya
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