Tag Clouds for Visualization

Tim comments over at the LibraryThing blog about click-based tag clouds, like this one from the State of Delaware website.

Click-based Tag Cloud

I’m not so sure why this seems surprising or innovative. Tim rightly notes that tag clouds are more commonly used to represent tagged items. But fundamentally, a tag cloud is just a kind of textual histogram, where

  • rather than a horizontal axis, the axis is wrapped across multiple lines (like text), making it more compact
  • rather than a bar whose height indicates magnitude, the font size (typically scaled) shows magnitude

So you can use a tag cloud for any kind of frequency distribution whose labels are textual. For example:

  • word counts from a document (i used to have Hyper-concordance views like this, though they’ve gone missing in action)
  • article titles for a blog, where the magnitude might be # of page views, # of citations by Google/del.icio.us/Connotea/you name it, # of sentences
  • wiki pages by # of outbound or inbound links
  • content and prosody measures for a text (see this old Blogos post)

I’m not surprised people like them: they can be a very effective visualization tool. But i am surprised people are surprised by the fact that they’re being used in more than just one way.