Embed bubble charts on a web site - charts

Question

I'm looking for a way to create what come to know to be called a "bubble chart" for a website I'm building. It needs to be compatible with IE7 and above, and of course all the good browsers like Firefox, Chrome and Safari. And no flash since this thing will need to run on iOS.
The chart needs to look like this, http://www.flickr.com/photos/jgrahamthomas/5591441300/
I've browse online and tried a few things, including:
Google Scatter Charts. This doesn't work as it seems Google Charts limits the size of a point to something smaller than I need. And Venn Diagrams are limited to three circles.
Protovis Dots. Great library, but isn't compatible with IE8.
Raphael Javascript. This one might be my best bet, but there's no explicit support for bubble charts.
Thanks for your help.

Answer 1

It looks like Raphael javascript is the way to go. It's compatible with IE6. I found a great tutorial at http://net.tutsplus.com/tutorials/javascript-ajax/an-introduction-to-the-raphael-js-library/ and am able to get the example working on my rails site with this code:
# window.onload = function() {
# var paper = new Raphael(document.getElementById('canvas_container'), 500, 500);
# var circle = paper.circle(100, 100, 80);
# for(var i = 0; i < 5; i+=1) {
# var multiplier = i*5;
# paper.circle(250 + (2*multiplier), 100 + multiplier, 50 - multiplier)
# }
# var rectangle = paper.rect(200, 200, 250, 100);
# var ellipse = paper.ellipse(200, 400, 100, 50);
# }

Answer 2

You can give Protovis a chance, the library looks good for your needs: http://vis.stanford.edu/protovis/ex/
Another charting library is Highcharts, but I haven't tried it yet: http://www.highcharts.com/

Answer 3

Have you had a look at flot?
It's a plotting library for jQuery. While it technically doesn't have any "native" support for bubble charts it is possible to create bubble charts with it by using a few tricks, the simplest one probably being to simply put each point in its own data series (thus allowing you to control the radius of each individual point.
By defining your points similar to this you'll be able to create a bubble chart:
var dataSet = [{
color:"rgba(0,0,0,0)", // Set the color so it's transparent
shadowSize:0, // No drop shadow effect
data: [[0,1],], // Coordinates of the point, normally you'd have several
// points listed here...
points: {
show:true,
fill:true,
radius: 2, // Here we set the radius of the point (or rather, all points
// in the data series which in this case is just one)
fillColor: "rgba(255,140,0,1)", // Bright orange :D
}
},
/* Insert more points here */
];

Answer 4

There is a bubble chart available for flot here
Note that you need to scale your bubbles size yourself if you don't want them to coverup the graph. Documentation is here.
To use it, add the following at the beggining of your html page:
and call it from a json result or any data object like in this sample:
$.getJSON('myQuery.py?'+params, function(oJson) {
// ... Some validation here to see if the query worked well ...
$.plot('#myContainer',
// ---------- Series ----------
[{
label: 'Line Sample',
data: oJson.lineData,
color: 'rgba(192, 16, 16, .2)',
lines: { show: true },
points: { show: false }
},{
label: 'Bubble Sample',
data: oJson.bubbleData, // arrays of [x,y,size]
color: 'rgba(80, 224, 80, .5)',
lines: { show: false },
points: { show: false },
},{
label: 'Points sample',
data: oJson.pointsData,
color: 'rgba(255, 255, 0, 1)',
lines: { show: false },
points: { show: true, fillColor: 'rgba(255, 255, 0, .8)' }
},{
...other series
}],
// ---------- Options ----------
{ legend: {
show: true,
labelBoxBorderColor: 'rgba(32, 32, 32, .2)',
noColumns: 6,
position: "se",
backgroundColor: 'rgba(224, 224, 224, .2)',
backgroundOpacity: .2,
sorted: false
},
series: {
bubbles: { active: true, show: true, fill: true, linewidth: 2 }
},
grid: { hoverable: true, clickable: true } },
xaxis: { tickLength: 0 }
}); // End of plot call
// ...
}); // End of getJSON call
I tried to do the same thing with jqPlot which has some advantages but doesn't work with bubbles and other kind of series on the same graph. Also Flot does a better job to synchronise common axis scale with many series. Highchart does a really good job here (mixing bubble chart with other kind of series) but isn't free for us (government context).