Charts - Polar Chart with Annotations

Annotations are containers for images, text blocks, and custom content that display additional information about the visualized data.

To create annotations, populate the PolarChart's annotations array. Each object in the array configures an individual annotation. To specify settings for all annotations, use the commonAnnotationSettings object. Individual settings take precedence over common settings.

You can set each annotation's type property to "text", "image", or "custom". This demo shows only "text" annotations.

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Backend API

@model IEnumerable<DevExtreme.NETCore.Demos.Models.DiscreteScaleTemperature> @{ var maxDay = Model.First(d => d.DayT == Model.Max(dd => dd.DayT)); var minNight = Model.First(d => d.NightT == Model.Min(dn => dn.NightT)); } @(Html.DevExtreme().PolarChart() .ID("radarChart") .DataSource(Model) .CommonSeriesSettings(s => s.Type(PolarChartSeriesType.Bar).ArgumentField("Date").Opacity(0.75)) .Series(s => { s.Add().ValueField("DayT").Name("Day").Color("#fdff5e"); s.Add().ValueField("NightT").Name("Night").Color("#0f3b59"); }) .CommonAnnotationSettings(ca => ca.Type(AnnotationType.Text).Opacity(0.7).ArrowLength(0)) .Annotations(a => { a.Add().Text("WINTER").Angle(45).Radius(180); a.Add().Text("SPRING").Angle(135).Radius(180); a.Add().Text("SUMMER").Angle(225).Radius(180); a.Add().Text("FALL").Angle(315).Radius(180); a.Add() .Argument(maxDay.Date) .Series("Day") .Text(String.Format("Highest temperature: {0} °C", maxDay.DayT)) .Opacity(1) .OffsetX(105) .PaddingTopBottom(15) .PaddingLeftRight(15); a.Add() .Argument(minNight.Date) .Series("Night") .Text(String.Format("Lowest temperature: {0} °C", minNight.NightT)) .Opacity(1) .OffsetX(105) .PaddingTopBottom(15) .PaddingLeftRight(15); }) .ArgumentAxis(a => { a.Strips(st => { st.Add().StartValue("December").EndValue("February").Color("#0076d1"); st.Add().StartValue("March").EndValue("May").Color("#3ca3b0"); st.Add().StartValue("June").EndValue("August").Color("#3fbc1e"); st.Add().StartValue("September").EndValue("November").Color("#f0bb00"); }); }) .Legend(l => l .HorizontalAlignment(HorizontalAlignment.Center) .VerticalAlignment(VerticalEdge.Bottom) ) .Title("Average temperature in London") )

using DevExtreme.AspNet.Data; using DevExtreme.AspNet.Mvc; using DevExtreme.NETCore.Demos.Models; using DevExtreme.NETCore.Demos.Models.SampleData; using Microsoft.AspNetCore.Mvc; using System; using System.Collections.Generic; using System.Linq; namespace DevExtreme.NETCore.Demos.Controllers { public class ChartsController : Controller { public ActionResult PolarChartAnnotations() { return View(SampleData.DiscreteScaleTemperatures); } } }

using System; namespace DevExtreme.NETCore.Demos.Models { public class DiscreteScaleTemperature { public string Date { get; set; } public double DayT { get; set; } public double NightT { get; set; } } }

using System; using System.Collections.Generic; namespace DevExtreme.NETCore.Demos.Models.SampleData { public partial class SampleData { public static readonly IEnumerable<DiscreteScaleTemperature> DiscreteScaleTemperatures = new[] { new DiscreteScaleTemperature { Date = "December", DayT = 7, NightT = 3 }, new DiscreteScaleTemperature { Date = "January", DayT = 6, NightT = 2 }, new DiscreteScaleTemperature { Date = "February", DayT = 7, NightT = 3 }, new DiscreteScaleTemperature { Date = "March", DayT = 10, NightT = 3 }, new DiscreteScaleTemperature { Date = "April", DayT = 14, NightT = 5 }, new DiscreteScaleTemperature { Date = "May", DayT = 18, NightT = 8 }, new DiscreteScaleTemperature { Date = "June", DayT = 21, NightT = 11 }, new DiscreteScaleTemperature { Date = "July", DayT = 22, NightT = 13 }, new DiscreteScaleTemperature { Date = "August", DayT = 21, NightT = 13 }, new DiscreteScaleTemperature { Date = "September", DayT = 19, NightT = 11 }, new DiscreteScaleTemperature { Date = "October", DayT = 15, NightT = 8 }, new DiscreteScaleTemperature { Date = "November", DayT = 10, NightT = 4 } }; } }

#radarChart { height: 600px; }

You can place annotations at specific coordinates or anchor them to PolarChart elements. This demo illustrates the following annotation placement methods:

Angle and radius properties specify the position of annotations with season names.
Annotations with temperatures are anchored to series points, and the offsetX, paddingTopBottom, and paddingLeftRight properties specify their position.

For more information on annotation settings, refer to the annotations[] help topic.