Machine learning libraries can be categorized using different criteria, which are explained in the sections that follow.
Free and open source libraries are cost-effective solutions, and most of them provide a framework that allows you to implement new algorithms on your own. However, support for these libraries is not as good as the support available for proprietary libraries. However, some open source libraries have very active mailing lists to address this issue.
Apache Mahout, OpenCV, MLib, and Mallet are some open source libraries.
MATLAB is a commercial numerical environment that contains a machine learning library.
Machine learning algorithms are resource-intensive (CPU, memory, ...