Fotherplot

After working out how to plot time-based data using Google charts API, I created a Wordpress plugin to plot values stored in a custom field against the published-on date of a Wordpress blog post.

This is an example of what it looks like:

This is what the image URL looks like:

<img src="http://chart.apis.google.com/chart?&cht=lxy&chs=450x300&chma=10,10,10,10&chds=0,384,98.9,116.1&chg=0,5&chxt=y,x&chxl=0:|98.9|102.34|105.78|109.22|112.66|116.1|1:|20/Jan/08|10/Mar/08|08/Oct/08|10/Jan/09|07/Feb/09&chm=D,FF0000,0,-1,1|o,000000,0,-1,4|N,000000,0,-1,9&chd=t:0,8,15,22,50,79,180,224,263,273,290,350,357,364,371,378,384|103.4,102.9,102.3,100.9,99.3,98.9,103.4,110.5,112.9,109.7,110,116.1,113.4,110.67,111.4,110,108.18" />

The plugin is hosted in the Wordpress plugins directory where you can find the installation instructions and a FAQ.

Software Change Log

• v0.0.9 (current version) - Modified code to use the shortcode API in order to allow parameters. Now we can use

  [fotherplot showlist=1]

  to show the list of posts that contain the data we're plotting. Note: You need to use "[fotherplot]", instead of "[[fotherplot]]".
• v0.0.8 - Fixed bug where the plugin settings page wasn't showing the chart. I was missing a "echo" statement.
• v0.0.7 - Fixed bug encountered when plugin is first installed and only 2 data items exist in posts published on the same day. Now gives an error message (instead of going into a infinite loop, i.e. crashing).
• v0.0.6 - No code change - just updated to new Changelog format and fixed broken screenshot images.
• v0.0.5 - Added a easy way to display the fotherplot chart. Just add

  [[fotherplot]]

  inside any page or post and the chart will be embedded. Also fixed a bug with the date labelling.
• v0.0.4 - Added a fotherplot settings page in the Wordpress dashboard where you can specify the custom field you want to chart (Yay! no need to touch PHP code anymore). Also added some error messages: e.g. displays error if non-numeric custom field values are used, or if not enough data is input or if no custom fields are available.
• v0.0.3 - Added a fotherplot page template so it's possible to use the plugin without installing the `phpexec' plugin. No functionality change in this release.
• v0.0.2 - First Wordpress plugin version. Two features: 1) Draw chart of custom field valid over time. 2) Display list of values in time order.
• v0.0.1 - Inital draft version (Not in proper Wordpress plugin format)

Related links

• 4/Mar/12 - I noticed that Google have a visualization for time-related data: http://code.google.com/apis/chart/interactive/docs/gallery/annotatedtimeline.html. Unfortunately, it's only in the advanced version of the chart API so it's not as simple to use as the simple image-based chart API.
• 11/Feb/09 - Matt Cutts from Google blogged about how he used Google spreadsheets to plot weight. His solution is much more robust than Fotherplot (but not as simple and easy to make into a Wordpress plugin?)