What free data mining libraries can you recommend?

Question

data mining

Actually, free libraries interest. Implementation in any language, preferably C++, Java, C#
Perhaps it will not be a library, but free software.
Thank you.

Answer 1

Weka

Answer 2

I highly recommend this project orange.biolab.si/ , I use it for quick iterations, many features, it works stably.

Answer 3

Apache Mahout

Answer 4

R