Sunday, 19 March 2017

Data Visualisation Open-Source Tool:Webcharts using Excel

Data visualisation can be performed in the browser and as our team are familiar with Microsoft Excel a solution to combine webcharts with Excel was explored. Chart.js is open-source framework and after creating a number of JavaScript samples; it was chosen as the charting framework.

The next challenge is to import Excel Spreadsheets into a JSON or Array Object. The open-source library JS-XLSX was tested, even though reviews highlighted its complexity. After setting up a Node.js server the main issue was to parse JSON in a cross browser compatible way. A Node.js server would store the Excel spreadsheets and run the import code. As the server had to have the ability to run Node.js Heroku was selected; as they provide a free Node.js container for non-commercial projects. Heroku integration with Github enables easy deployment of applications.

A HTML5 boilerplate was downloaded along with Heroku's Node.js Starter Kit. Chart.js was installed using the NPM package manager along with JS-XLSX.

Completed application is located here (as iframes to be included in a DH6010 Blogpost)

https://dh6010.herokuapp.com/iframes/iframes.html

The DH6010 Data Visualisation App is located @ https://bitbucket.org/MuddyGames/dh6010

Import and Webchart JavaScript

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<!doctype html>
<html class="no-js" lang="">
    <head>
        <meta charset="utf-8">
        <meta http-equiv="x-ua-compatible" content="ie=edge">
        <title id="page_title"><title>
        <link rel="stylesheet" href="/stylesheets/graph.css">

  <script type="text/javascript" src="/engine/jquery/scripts/jquery.min.js"></script>
  <script type="text/javascript" src="/engine/chart.js/scripts/Chart.min.js"></script>
  <script type="text/javascript" src="/engine/xlsx/scripts/xlsx.full.min.js"></script>

  <script>
  function get(name){
      if(name=(new RegExp('[?&]'+encodeURIComponent(name)+'=([^&]*)')).exec(location.search))
        return decodeURIComponent(name[1]);
  }


  function loadSpreadsheet(filename, chart_type, chart_title) {

   // Define Vars
   var request;
   var keys = [];
   var values = [];


   if (window.XMLHttpRequest) {
       request = new XMLHttpRequest();
   } else {
       // code for older browsers
       request = new ActiveXObject("Microsoft.XMLHTTP");
   }
   request.onreadystatechange = function() {
       if (this.readyState == 4 && this.status == 200) {
       }
   };

   request.open("GET", "./spreadsheets/" + filename, true);
   request.responseType = "arraybuffer";

   request.onload = function(e) {
    var arraybuffer = request.response;
      var data = new Uint8Array(arraybuffer);
      var arr = new Array();
      for(var i = 0; i != data.length; ++i) arr[i] = String.fromCharCode(data[i]);
      var bstr = arr.join("");
      var workbook = XLSX.read(bstr, {type:"binary"});
      var first_sheet_name = workbook.SheetNames[0];
      var worksheet = workbook.Sheets[first_sheet_name];

      var roa = XLSX.utils.sheet_to_row_object_array(workbook.Sheets[first_sheet_name]);

      for (var i = 0; i < roa.length; i++) {
       var row = roa[i];

       if(i == 0){
        $.each(row,function(value, index){ 
           keys.push(value);
          }
        );
       }

       $.each(row,function(value, index){ 
          values.push(row[value]);
         }
       );
      }


       var ctx = document.getElementById("chart");

    var chart = new Chart(ctx, {
     type: chart_type,
     data: {
         labels: keys,
          datasets: [{
             label: chart_title,

             fill: false,
                lineTension: 0.1,
                backgroundColor: border_Color,
                borderColor: border_Color,
                borderCapStyle: 'butt',
                borderDash: [],
                borderDashOffset: 0.0,
                borderJoinStyle: 'miter',
                pointBorderColor: border_Color,
                pointBackgroundColor: "#fff",
                pointBorderWidth: 1,
                pointHoverRadius: 5,
                pointHoverBackgroundColor: border_Color,
                pointHoverBorderColor: border_Color,
                pointHoverBorderWidth: 2,
                pointRadius: 1,
                pointHitRadius: 10,

             data: values,
             }]
         },
         options: {
             scales: {
                 yAxes: [{
                     ticks: {
                         beginAtZero:true
                     }
                 }]
             }
         }
     });
   }

   request.send();
  }

  var page_title = get("page_title");
  var filename  = get("filename");
  var chart_type  = get("chart_type");
  var chart_title = get("chart_title");
  var border_Color = get("border_Color");

  window.onpaint = loadSpreadsheet(filename, chart_type, chart_title);

  </script>

 <body>
  <h2 id="chart_title"></h2>

     <div class="container">
         <div class="container">
             <canvas id="chart"></canvas>
         </div>
     </div>

     <script type="text/javascript">
      document.getElementById("chart_title").innerHTML = page_title;
      document.getElementById("page_title").innerHTML = page_title;
     </script>

 </body>


</html>

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