Are there any machine learning libraries for Ruby that are relatively complete (including a wide variety of algorithms for supervised and unsupervised learning), robustly tested, and well-documented? I love Python's scikit-learn for its incredible documentation, but a client would prefer to write the code in Ruby since that's what they're familiar with.
Ideally I am looking for a library or set of libraries which, like
numpy, can implement a wide variety of data structures like sparse matrices, as well as learners.
Some examples of things we'll need to do are binary classification using SVMs, and implementing bag of words models which we hope to concatenate with arbitrary numeric data, as described in this StackOverflow post.