{"id":10842,"date":"2020-07-07T05:25:55","date_gmt":"2020-07-07T05:25:55","guid":{"rendered":"https:\/\/www.anychart.com\/blog\/?p=10842"},"modified":"2022-08-13T11:00:06","modified_gmt":"2022-08-13T11:00:06","slug":"radar-chart-js","status":"publish","type":"post","link":"https:\/\/www.anychart.com\/blog\/2020\/07\/07\/radar-chart-js\/","title":{"rendered":"Building JavaScript Radar Chart"},"content":{"rendered":"

\"TutorialRadar charts<\/a>, which are also referred to as spider charts or radar plots, are a data visualization used to compare observations with multiple quantitative variables. Each variable is encoded to a spoke which are equidistant apart. The higher the value, the further away from the center of the chart the point is made. Radar charts are best used to compare the \u2018profile\u2019 of observations and to detect outliers within the data. They are therefore used quite a bit in sports, most notably in basketball and soccer for profiling players<\/a>.<\/p>\n

In this tutorial I will be teaching you how to build your own radar chart with JavaScript<\/strong> and how to use them to help with one of the toughest decisions in gaming history: which starting pokemon to choose<\/strong>!<\/p>\n

That\u2019s right, we will be building radar charts to perform data analysis on Bulbasaur, Charmander and Squirtle to determine, once and for all, which is the best choice.<\/p>\n

<\/p>\n

Building a JavaScript radar chart<\/h2>\n

To build our radar charts we will be using a charting library. Charting libraries remove a lot of the burden of building charts (compared to something like d3.js) and allow you to get a chart up quickly and easily. For this tutorial I\u2019ve chosen to use AnyChart JavaScript library<\/a>. I\u2019ve chosen AnyChart because building charts with it is really quick and it\u2019s a awesome library for beginners because of the pretty intensive documentation<\/a>.<\/p>\n

Step 1: Setup the page<\/h3>\n

The first step to create our radar charts is to setup the html page and load the required scripts.<\/p>\n

<html>\r\n  <head>\r\n    <script src=\"https:\/\/cdn.anychart.com\/releases\/8.7.1\/js\/anychart-core.min.js\"><\/script>\r\n    <script src=\"https:\/\/cdn.anychart.com\/releases\/8.7.1\/js\/anychart-radar.min.js\"><\/script>\r\n    <style type=\"text\/css\">\r\n      html, body, #container {\r\n        width: 100%;\r\n        height: 100%;\r\n        margin: 0;\r\n        padding: 0;\r\n      }\r\n    <\/style>\r\n  <\/head>\r\n  <body>\r\n    <div id=\"container\"><\/div>\r\n    <script>\r\n      anychart.onDocumentReady(function () {\r\n        \/\/ drawing our chart goes here\r\n      });\r\n    <\/script>\r\n  <\/body>\r\n<\/html><\/code><\/pre>\n
All I have done here is created a new html page, added the scripts required for creating a radar chart anychart-core.min.js<\/a>\u00a0and anychart-radar.min.js<\/a>. The former is required for all AnyChart charting and comes with the basic charts (scatter, bar etc) while the latter gives us the module required for building a radar chart.<\/p>\n
We then create a CSS rule for our html page which sets the size of our chart. We have gone for 100% width and height and 0 margins to create a full screen data viz but if you want something different go ahead and change those values to something that better suits your needs.<\/p>\n
Lastly, we use anychart.onDocumentReady()<\/code>. Our chart will go in this function. What this does is it triggers the function only when the document is ready and not before.<\/p>\n
Step 2: Load the data<\/h3>\n
In order to draw radar charts for our starter Pokemon we need to get the data. I found this at bulbapedia.bulbagarden.net<\/a> (how cute?) which seems to have the stats for every Pokemon ever!<\/p>\n
\"Snapshot<\/p>\n
We then need to reformat this data into something that AnyChart knows how to read. AnyChart likes the data for each observation in the following format:<\/p>\n
var data1 = [\r\n  {x: \"HP\", value: 39},\r\n  {x: \"Attack\", value: 52},\r\n  {x: \"Defense\", value: 43},\r\n  {x: \"Special Attack\", value: 60},\r\n  {x: \"Special Defense\", value: 50},\r\n  {x: \"Speed\", value: 65},\r\n];<\/code><\/pre>\n
An array of objects with each variable having the x-axis variable to be named \u2018x\u2019 and the y-axis variable to be named \u2018value\u2019. In the radar chart\u2019s case, the x-axis variable is the name of the variable while the y-axis variable is the value.<\/p>\n
We repeat this step for each starter Pokemon resulting in the following three arrays:<\/p>\n
var data1 = [\r\n  {x: \"HP\", value: 39},\r\n  {x: \"Attack\", value: 52},\r\n  {x: \"Defense\", value: 43},\r\n  {x: \"Special Attack\", value: 60},\r\n  {x: \"Special Defense\", value: 50},\r\n  {x: \"Speed\", value: 65},\r\n];\r\n \r\nvar data2 = [\r\n  {x: \"HP\", value: 45},\r\n  {x: \"Attack\", value: 49},\r\n  {x: \"Defense\", value: 49},\r\n  {x: \"Special Attack\", value: 65},\r\n  {x: \"Special Defense\", value: 65},\r\n  {x: \"Speed\", value: 45},\r\n]; \r\n \r\nvar data3 = [\r\n  {x: \"HP\", value: 44},\r\n  {x: \"Attack\", value: 48},\r\n  {x: \"Defense\", value: 65},\r\n  {x: \"Special Attack\", value: 50},\r\n  {x: \"Special Defense\", value: 64},\r\n  {x: \"Speed\", value: 43},\r\n];<\/code><\/pre>\n
Step 3: Drawing the chart<\/h3>\n
Now that we have all of our (psy)ducks in a row it is time to draw our chart.<\/p>\n
\/\/ create radar chart\r\nvar chart = anychart.radar();\r\n\r\n\/\/ set chart title\r\nchart.title(\"Starter Pokemon Comparison Chart\");\r\n\r\n\/\/ set chart yScale settings\r\nchart.yScale()\r\n  .minimum(0)\r\n  .maximum(100)\r\n  .ticks({'interval':20});\r\n\r\n\/\/ create first series\r\nchart.line(data1)\r\n\/\/ create second series\r\nchart.line(data2)\r\n\/\/ create third series\r\nchart.line(data3)\r\n\r\n\/\/ set container id for the chart\r\nchart.container('container');\r\n\/\/ initiate chart drawing\r\nchart.draw();<\/code><\/pre>\n
Which results in:<\/p>\n
\"Basic<\/p>\n
This doesn\u2019t look too informative does it? The different series all look the same. We can easily fix this though. If we change the minimum and the maximum yScale values we will be able to see the differences between our 3 series much better. I then set the maximum value to 65 and the minimum value to 35, I chose these values based on the data I am trying to visualize. If one of our pokemon had a variable with a value higher than 65 or lower than 35 I would have chosen different values to accommodate that.<\/p>\n
\/\/ set chart yScale settings\r\nchart.yScale()\r\n  .minimum(35)\r\n  .maximum(65)\r\n  .ticks({'interval':5});<\/code><\/pre>\n
Which results in this:<\/p>\n