C++ implementation of the paper Bonsai - Diverse and Shallow Trees for Extreme Multi-label Classification

• Extreme Multi-Label Classification (XMC) refers to supervised learning of a classifier which can automatically label an instance with a subset of relevant labels from an extremely large set of all possible target labels. Bonsai learns an ensemble of diversity promoting shallow trees which achieves accuracies at par with the state-of-the-art one-vs-rest methods while being much faster to train.
• A tree built by Bonsai differs from one built by Parabel in the following aspects,
  1. A larger fanout at every node i.e instead of the two-way partioning of labels done by Parabel, Bonsai does a k-way partitioning. (k was set to 100 for most of our experiements)
  2. Allowing unbalanced partitioning of labels at every internal tree node thus producing a more data-dependent partitioning.
  3. Shallower i.e having much lesser number of levels in the tree.

• The code for Bonsai is written in C++ and thus requires C++11 enabled compilers.
• To compile, run the make command from inside the shallow directory
• A sample script sample_run.sh is provided inside the shallow directory which trains the model and computes the metrics for the EUR-Lex dataset.
• The usage of Bonsai for other datasets can be achieved from the above-mentioned sample_run.sh script by setting parameter -m to 2 for smaller datasets like EUR-Lex, Wikipedia-31K and to 3 for larger datasets like Delicious-200K, WikiLSHTC-325K, Amazon-670K, Wikipedia-500K, Amazon-3M.

• A script convert_data.sh is provided in the sandbox directory to convert the raw train/test datasets from the XMC repository to the format needed by Bonsai.
• Scripts for performance evaluation are only available in Matlab. To compile these scripts, execute make in the tools/matlab folder from the Matlab terminal.

The code is adapted from the source code kindly provided by the authors of Parabel: Partitioned Label Trees for Extreme Classification with Application to Dynamic Search Advertising