PocketSmith

After messing around with the Google Charts API for a good 12 hours or so, I realised very quickly the limitations of the solution. Although this system does have its positive aspects, there were a few omissions that resulted in us moving way from Google Charts.

• Inability to handle negative numbers
• Axes labels that are set based upon spacing (i.e. at the bottom, half way up, at the top), not the data it represents
• Inflexibility when it comes to tooltips / displaying the values at a particular point

This first of these can be worked around with a hack which can be seen here, however although this works well for relatively stable, administrator created graphs, it gets a bit hairier when we are graphing user data. And offsetting data just to get it to display correctly is just, well, painful (despite the fact that I had some pretty nifty calculations happening to find the zero-point line on a scale of 0% to 100% between the maximum and minimum values to be graphed - not that this helped at all or anything).

The second is a bit of show-stopper - basically you define where the axes are placed but the number of items that you provide Google. This means that giving it (0, 50, 100) would set 0 at the bottom, 50 half way up and 100 at the top. (0, 25, 50, 75, 100) would break the axes into five regions. Ugly.

The third… well. I was hoping to get at least a little bit of the way towards really nice Google Analytics type graphing interaction, but no dice, not here.

So I went back out onto the market as it were to find other alternatives that would not add additional strain onto the server. Flash based chart tools best fit into this category, and boy did I luck out.

I found the Open Flash Chart project, which is damn near perfect for what we require. All processing is done on the user’s machine through the embedded flash file, which gets passed data from our Ruby on Rails application.

A nice little plugin / Rails wrapper for Open Flash Chart is provided by the good people at PullMonkey, who ported the PHP wrapper to Rails. This means that we now have graphs the handle negative numbers, have automatic axes label generation, and little tooltips showing the specific value of a day on hover. So basically we now have graphs that a much more user-friendly, being generated by the wonders of Flash.

So the lesson I have learned - dig a bit deeper before deciding on a solution!

Tags: charts, development, Ruby on Rails

This entry was posted on Thursday, July 17th, 2008 at 4:50 pm and is filed under Ruby on Rails. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.