Ruby visualization toolkit

 Ruby port of Protovis.
 .
 Protovis composes custom views of data with simple marks such as
 bars and dots. Unlike low-level graphics libraries that quickly
 become tedious for visualization, Protovis defines marks through
 dynamic properties that encode data, allowing inheritance, scales
 and layouts to simplify construction.
 .
 This library implements almost completely core API of protovis,
 including all static marks, SVG builder class and data classes.