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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. Protovis is free and open-source, provided under the BSD License . It uses JavaScript and SVG for web-native visualizations; no plugin required (though you will need a modern web browser)!
Protovis