To improve my Clojure skills, I decided to tackle a small self-contained problem with results that are quick and fun. I was surprised to discover how little code was required to satisfy my goal of generating and plotting L-system data.

More specifically, I wanted to generate axial trees, mostly because they are beautiful to look at, but also because it requires the additional step of implementing a Bracketed OL-system, since the definition of tree L-systems does not specify the data structure for representing axial trees.

The code is probably of little practical re-use value, but you are free to do what you like with it.

If you have Leiningen installed, you probably already know the drill:

lein deps
lein repl

Once in the REPL you can generate an L-system pattern by specfiying the grammar name and the nth generation that you want:

l-system.display=> (generate dragon-curve 5)
"FX+YF+FX-YF+FX+YF-FX-YF+FX+YF+FX-YF-FX+YF-FX-YF+FX+YF+FX-YF+FX+YF-FX-YF-FX+YF+FX-YF-FX+YF-FX-YF"

... or for an axial tree:

l-system.display=> (generate axial-tree-f 2)
"FF-[[F-[[X]+X]+F[+FX]-X]+F-[[X]+X]+F[+FX]-X]+FF[+FFF-[[X]+X]+F[+FX]-X]-F-[[X]+X]+F[+FX]-X"

To view graphical output of applets that plot using the constants (commands) of these L-systems:

l-system.display=> (run tree-f-app)
l-system.display=> (stop tree-f-app)

Other applets include the sierpinski triangle (sierpinski-app). Check src/display.clj for more applet definitions.

Copyright (C) 2011 Scott Lowe

Licensed under the terms of the MIT License