Algorithm to implement something like Wordle

Question

Context

• Take a look at what wordle does : http://www.wordle.net/
• it's much better looking than any other word cloud generators I've seen
• note: the source is not avaialable - read the FAQ http://www.wordle.net/faq#code

My Questions

• Is there an algorithm available that does what Worlde does?
• If no, what are some alternatives that produces similar kinds of output

Why I'm asking

• just curious
• want to learn

Answer 1

http://code.google.com/apis/visualization/documentation/gallery.html

Check out the word cloud visualization. Not as fancy as wordle.net but real easy to add to your site.

Answer 2

I'm the creator of Wordle. Here's how Wordle actually works:

Count the words, throw away boring words, and sort by the count, descending. Keep the top N words for some N. Assign each word a font size proportional to its count. Generate a Java2D Shape for each word, using the Java2D API.

Each word "wants" to be somewhere, such as "at some random x position in the vertical center". In decreasing order of frequency, do this for each word:

place the word where it wants to be
while it intersects any of the previously placed words
    move it one step along an ever-increasing spiral

That's it. The hard part is in doing the intersection-testing efficiently, for which I use last-hit caching, hierarchical bounding boxes, and a quadtree spatial index (all of which are things you can learn more about with some diligent googling).

Answer 3

I've implemented an algorithm as described by Jonathan Feinberg using python to create a tag cloud. It is far away from the beautiful clouds of worlde.net but it gives you an idea how it could be done.

You can find the project here.