Tag: google

I’m in need of graphing some data, and since I looked at the Google Chart Tools long ago but never did anything interesting with it, I figured I’d give it a spin.

Google’s API is pretty simple to use, you feed it a URL, and you get an image in return. Here’s an example expanded out a bit:

http://chart.apis.google.com/chart?
  cht=lc&
  chs=600x400&
  chg=10,5,5,5&
  chco=ff0000&
  chxt=x,y&
  chxr=1,0,100,5|0,0,24,1&
  chd=t:3,3,3,3,3,3,3,65,38,46,60,59,56,58,36,21,13,62,2,3,3,3,3,2

Each parameter controls some part of the image you get returned. (Want to see it? View the URL.)

You should get something that looks like this:

Wow… but not really. This is probably one of the simplest examples of a chart, but it serves my purpose.

Of course, since I’m not always content relying on others to host my data, I wanted a way to generate and store the image. You can do that too…

curl -o 20101130.png 'http://chart.apis.google.com/chart?cht=lc&chs=600x400&chg=10,5,5,5&chco=ff0000&chxt=x,y&chxr=1,0,100,5|0,0,24,1&chd=t:3,3,3,3,3,3,3,65,38,46,60,59,56,58,36,21,13,62,2,3,3,3,3,2'

Just use curl to make the request and store the image in a file named 20101130.png (or whatever the date is, or file name you’d prefer.) Obviously you’ll need curl installed. If you need to generate a new chart everyday this is ripe for automating.

I also looked at jQuery Visualize as an option. It’s quite different than the Google Chart API as to how it functions.

With jQuery Visualize you don’t actually create a chart. Well, you do create a table of data, and jQuery Visualize does all the heavy lifting and creates the chart based entirely on your well-formed tabular data.

I sort of like this approach because there’s no external image files to generate, host, or worry about. You just make a table, and include a bit of Javascript. (Of course there are other concerns/issues, but simplicity is pretty high.)

I’m still evaluating what my final choice will be for my current project. If this were 10 years ago, I probably would have used Perl to generate the image files. If it were 5 years ago, I probably would have used Perl to generate some SVG files…

jQuery Visualize uses the HTML 5 Canvas element, so they get some points in the “innovation” column I guess… Also, jQuery Visualize requires less math, and in my world, the less math I have to do, the better!