How to use polar coordinate system to display data in ECharts

How to use polar coordinate system to display data in ECharts

1. Introduction
ECharts is an open source visualization library developed based on JavaScript, which provides a wealth of The chart types and interactive capabilities make it easy to visually display data. Among them, polar coordinate system is a type of coordinate system commonly used in ECharts. It can display data in polar coordinates, making the relationship between data clearer. This article will introduce how to use the polar coordinate system to display data in ECharts, and provide some specific code examples.

2. Basic configuration
Before using ECharts to display polar coordinate system data, we first need to perform some basic configuration. In the tag of the HTML page, introduce the JavaScript file of ECharts:

<script src="echarts.min.js"></script>

Then, add a <div># with a certain width and height to the page. ##Element, used to accommodate ECharts charts: <pre class='brush:html;toolbar:false;'>&lt;div id=&quot;chart&quot; style=&quot;width: 600px; height: 400px;&quot;&gt;&lt;/div&gt;</pre> Next, we need to create an ECharts instance in the JavaScript code and obtain the corresponding DOM element: <p><pre class='brush:javascript;toolbar:false;'>var chart = echarts.init(document.getElementById('chart'));</pre></p> 3. Data preparation <p>Before displaying polar coordinate system data, we need to prepare the data to be displayed. Suppose we have a set of two-dimensional data. Each data consists of two values: angle and radius. It can be saved using the following data structure: <br><pre class='brush:javascript;toolbar:false;'>var data = [ [10, 50], [45, 80], [90, 70], // ... ];</pre></p>4. Use the polar coordinate system to display the data<p>Next, We can use the <br>polar<code> configuration item provided by ECharts to define a polar coordinate system. After initializing the ECharts instance, we can configure the relevant style and content of the chart by calling the setOption method:

chart.setOption({
  polar: {},
  series: [{
    type: 'scatter',
    coordinateSystem: 'polar',
    data: data
  }]
});

Among them, the value of the

polar configuration item is an empty object {}, means we use the default polar coordinate system settings. seriesThe configuration item is used to configure the series type used by the chart. Here we use 'scatter'scatter chart series to display data. The value of the coordinateSystem configuration item is 'polar', indicating that the series uses the polar coordinate system to display data. dataThe configuration item is the data prepared previously.

5. Customized style

In addition to the basic polar coordinate system configuration, we can also customize the style of the chart. The following are some commonly used custom configuration examples:

Adjust the radius range of the polar coordinate system:

1. polar: {
     radius: ['20%', '80%']
   }

Add axes and scales:

2. polar: {
     radiusAxis: {
       show: true,
       splitLine: {
         show: true
       },
       axisLine: {
         show: true
       }
     },
     angleAxis: {
       show: true,
       splitLine: {
         show: true
       },
       axisLine: {
         show: true
       }
     }
   }

Customize the style of scatter plot:

3. series: [{
     type: 'scatter',
     coordinateSystem: 'polar',
     data: data,
     symbol: 'circle',
     symbolSize: 10,
     itemStyle: {
       color: '#ff0000'
     }
   }]

6. Summary

This article introduces how to use the polar coordinate system to display data in ECharts, and provides some Specific code examples. I hope that through the introduction of this article, readers can master how to configure and use the polar coordinate system, and set custom styles according to actual needs. For more detailed configuration options, please refer to the ECharts official documentation.