Adding interactive scatterplots to your website

To use the scatterplots presented in my previous post, this is what you need.

  • My scatterplot javascript code (LGPL) available for download here.
  • A dataset stored in JSON, with the structure explained below
  • Add .js files to HTML header
  • HTML canvas elements in your html
  • Assignment of data to axes and plots to canvas in javascript

Dataset structure

Datasets for use in my scatterplot code is structured as a JSON array named “dataArray” containing n maps. Each map contains n “name”:value pairs which each is considered a single datapoint. The values to be used in a scatterplot of course need to be numerical. An example of a valid dataset structure is shown below. This is all put in a .js file, and returned by a function named datasetForVisualization() as shown below.

//of course more data in a real dataset
datasetForVisualization() {
   return {"dataArray":
      [{"punctuationprword":2.0,"ekstrem":0.0"},
      {"punctuationprword":6.0,"ekstrem":0.0"},
      {"punctuationprword":0.1111111111111111,"ekstrem":0.0}]
}

Add .js files to head

To add the .js files to your page, add these tags inside the head tag of your website:

<script src="data.js"></script>
<script src="geometry.js"></script>
<script src="guielements.js"></script>
<script src="selection.js"></script>
<script src="plots.js"></script>
<script src="dataset.js"></script>

HTML canvas elements

HTML5 canvas elements are created in the html parts of you website, and are created like this:

<canvas id="plot" width="640" height="480"><canvas>

The id parameter is needed since this is what you need to refer to when drawing to the canvas using javascript.

Assignment to canvas

The following javascript code will assign datasets parts to axes in the scatterplots, as well as tie the plot to a specific canvas and link with another scatterplot

<script type="text/javascript">
   //Select data for plot
   var data = create2DDataFromJson("punctuationprword","ekstrem");

   //Reference to canvas element created above
   var canvas = document.getElementById("plot");

   //Create plot
   var plot = new Scatterplot(canvas,data,540,400,
   "Punctuation pr word","Instances of ekstrem",false);

   //Link plot to other scatterplots
   plot.addLinked(plot2);
   plot2.addLinked(plot);
</script>

Hopefully this explains how to use the scatterplot as part of a webpage. To successfully use it within a WordPress blog is slightly more difficult. One of my next posts will go more into detail about that specifically. If you have any questions about usage please post a comment.