Weka

Weka is a complete set of tools that allow you to extract useful information from large databases. This process is commonly called as data mining.

You can work with filters, clusters, classify data, perform regressions, make associations, etc. Weka includes two executable options: command line or graphical user interface (GUI). The command line interface allows you to execute more functions and uses less memory than the GUI. But the GUI is simpler. The GUI's main menu "Weka GUI Chooser", includes access to the four Weka's main applications: Explorer, Experimenter, KnowledgeFlow and SimpleCLI, but also includes useful features to capture all the worked-out information; view ARFF files in spread-sheet format; represent querying databases in SQL worksheets, and includes tools to work with Bayes nets. One very important aspect of Weka is that you can choose the way the information will be displayed: you can plot a dataset in 2D, plot a receiver operating characteristic (ROC), display direct graphs such as decision trees, visualize XML BIF and DOT format graphs, and visualize classifier decision boundaries in two dimensions.