Wednesday, March 10, 2010

Tag clouds

Verrry cool tag clouds.
tag cloud or word cloud (or weighted list in visual design) is a visual depiction of user-generated tags, or simply the word content of a site, typically used to describe the content of web sites. Tags are usually single words and are normally listed alphabetically, and the importance of a tag is shown with font size or color. Thus, both finding a tag by alphabet and by popularity are possible. The tags are usually hyperlinks that lead to a collection of items that are associated with a tag.

In principle, the font size of a tag in a tag cloud is determined by its incidence. For a word cloud of categories like weblogs, the frequency of use for example, corresponds to the number of weblog entries that are assigned to a category. For small frequencies it's sufficient to indicate directly for any number from one to a maximum font size. For larger values, a scaling should be made. In a linear normalization, the weight ti of a descriptor is mapped to a size scale of 1 through f, where tmin and tmax are specifying the range of available weights.

s_i = \left \lceil \frac{f_{\mathrm{max}}\cdot(t_i - t_{\mathrm{min}})}{t_{\mathrm{max}}-t_{\mathrm{min}}} \right \rceil for ti > tmin; else si = 1

  • si: display fontsize
  • fmax: max. fontsize
  • ti: count
  • tmin: min. count
  • tmax: max. count

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