Data Labels in ASP.NET Core Chart
18 Nov 201811 minutes to read
Data label can be added to a chart series by enabling the visible option in the dataLabel. By default, the labels will arrange smartly without overlapping.
Position
Using position property, you can place the label either on Top, Middle, Bottom or Outer (outer is applicable for column and bar type series).
NOTE
The position
Outeris applicable for column and bar type series.
Data Label Template
Label content can be formatted by using the template option. Inside the template, you can add the placeholder text ${point.x} and ${point.y} to display corresponding data points x & y value. Using template property, you can set data label template in chart.
Text Mapping
Text from the data source can be mapped using name property.
Format
Data label for the chart can be formatted using format property. You can use the global formatting options, such as ‘n’, ‘p’, and ‘c’.
| Value | Format | Resultant Value | Description |
|---|---|---|---|
| 1000 | n1 | 1000.0 | The number is rounded to 1 decimal place. |
| 1000 | n2 | 1000.00 | The number is rounded to 2 decimal places. |
| 1000 | n3 | 1000.000 | The number is rounded to 3 decimal place. |
| 0.01 | p1 | 1.0% | The number is converted to percentage with 1 decimal place. |
| 0.01 | p2 | 1.00% | The number is converted to percentage with 2 decimal place. |
| 0.01 | p3 | 1.000% | The number is converted to percentage with 3 decimal place. |
| 1000 | c1 | $1000.0 | The currency symbol is appended to number and number is rounded to 1 decimal place. |
| 1000 | c2 | $1000.00 | The currency symbol is appended to number and number is rounded to 2 decimal place. |
Margin
The margin for data label can be applied to use left, right, bottom and top properties.
Customization
The stroke and border of data label can be customized using fill and border properties. Rounded corners can be customized using rx and ry properties.
NOTE
rxandryproperties requiresbordervalues not to be null.
Customizing Specific Point
You can also customize the specific marker and label using pointRender and textRender event. The pointRender event allows to change the shape, color and border for a point, whereas the textRender event allows to change the text for the point.
Show percentage based on each series points
You can calculate the percentage value based on the sum for each series using the seriesRender and textRender events in the chart. In seriesRender calculate the sum of each series y values and In textRender calculate percentage value based on the sum value and modify the text.
<div class="control-section">
<div id="container" align='center'>
<ejs-chart id="lineContainer" textRender="onTextRender" seriesRender="onSeriesRender" title="Olympic Medal Counts - RIO">
<e-chart-tooltipsettings enable="true">
</e-chart-tooltipsettings>
<e-chart-primaryxaxis valueType="Category" interval=1>
<e-majorgridlines width="0"></e-majorgridlines>
</e-chart-primaryxaxis>
<e-chart-primaryyaxis>
<e-majorgridlines width="0"></e-majorgridlines>
<e-majorticklines width="0"></e-majorticklines>
<e-linestyle width="0"></e-linestyle>
<e-labelstyle color="transparent"></e-labelstyle>
</e-chart-primaryyaxis>
<e-chart-chartarea>
<e-chartarea-border width="0"></e-chartarea-border>
</e-chart-chartarea>
<e-series-collection>
<e-series dataSource="ViewBag.dataSource1" xName='x' yName='y' name='Gold' width=2 type="@Syncfusion.EJ2.Charts.ChartSeriesType.Column">
<e-series-marker>
<e-series-datalabel visible="true" position="Top">
<e-font color="#ffffff" fontWeight="600"></e-font>
</e-series-datalabel>
</e-series-marker>
</e-series>
<e-series dataSource="ViewBag.dataSource2" xName='x' yName='y' name='Silver' width=2 type="@Syncfusion.EJ2.Charts.ChartSeriesType.Column">
<e-series-marker>
<e-series-datalabel visible="true" position="Top">
<e-font fontWeight="600" color="#ffffff"></e-font>
</e-series-datalabel>
</e-series-marker>
</e-series>
<e-series dataSource="ViewBag.dataSource3" xName='x' yName='y' name='Bronze' width=2 type="@Syncfusion.EJ2.Charts.ChartSeriesType.Column">
<e-series-marker>
<e-series-datalabel visible="true" position="Top">
<e-font fontWeight="600" color="#ffffff"></e-font>
</e-series-datalabel>
</e-series-marker>
</e-series>
</e-series-collection>
</ejs-chart>
</div>
</div>
<script>
var total = [];
function onSeriesRender(args) {
for (var i = 0; i < args.data.length; i++) {
if (!total[args.data[i].x]) total[args.data[i].x] = 0;
total[args.data[i].x] = total[args.data[i].x] + parseInt(args.data[i].y);
}
}
function onTextRender(args) {
var percentage = (parseInt(args.text) / total[args.point.x]) * 100;
percentage = percentage % 1 === 0 ? percentage : percentage.toFixed(2);
args.text = percentage + "%";
}
</script>public ActionResult Index()
{
List<ColumnChartData> chartData1 = new List<ColumnChartData>
{
new ColumnChartData { x= "USA", y = 46 },
new ColumnChartData { x= "GBR", y = 27 },
new ColumnChartData { x= "CHN", y = 26 }
};
ViewBag.dataSource1 = chartData1;
List<ColumnChartData> chartData2 = new List<ColumnChartData>
{
new ColumnChartData { x= "USA", y = 37 },
new ColumnChartData { x= "GBR", y = 23 },
new ColumnChartData { x= "CHN", y = 18 }
};
ViewBag.dataSource2 = chartData2;
List<ColumnChartData> chartData3 = new List<ColumnChartData>
{
new ColumnChartData { x= "USA", y = 38 },
new ColumnChartData { x= "GBR", y = 17 },
new ColumnChartData { x= "CHN", y = 26 }
};
ViewBag.dataSource3 = chartData3;
return View();
}
public class ColumnChartData
{
public string x;
public double y;
}