mlpack: a scalable C++ machine learning library

mlpack is an intuitive, fast, scalable C++ machine learning library, meant to be a machine learning analog to LAPACK. It aims to implement a wide array of machine learning methods and functions as a "swiss army knife" for machine learning researchers.

Download current stable version (1.0.12).

Contents

Introduction
Citation details
Dependencies
Building mlpack from source
Running mlpack programs
Further documentation
Bug reporting
Introduction

The mlpack website can be found at http://www.mlpack.org and contains numerous tutorials and extensive documentation. This README serves as a guide for what mlpack is, how to install it, how to run it, and where to find more documentation. The website should be consulted for further information:

Citation details

If you use mlpack in your research or software, please cite mlpack using the citation below (given in BiBTeX format):

@article{mlpack2013,
  title     = {{MLPACK}: A Scalable {C++} Machine Learning Library},
  author    = {Curtin, Ryan R. and Cline, James R. and Slagle, Neil P. and
               March, William B. and Ram, P. and Mehta, Nishant A. and Gray,
               Alexander G.},
  journal   = {Journal of Machine Learning Research},
  volume    = {14},
  pages     = {801--805},
  year      = {2013}
}

Citations are beneficial for the growth and improvement of mlpack.

Dependencies

mlpack has the following dependencies:

  Armadillo     >= 3.6.0
  LibXml2       >= 2.6.0
  Boost (program_options, math_c99, unit_test_framework, random)
  CMake         >= 2.8.5

All of those should be available in your distribution's package manager. If not, you will have to compile each of them by hand. See the documentation for each of those packages for more information.

If you are compiling Armadillo by hand, ensure that LAPACK and BLAS are enabled.

Building mlpack from source

(see also Building mlpack From Source)

mlpack uses CMake as a build system and allows several flexible build configuration options. One can consult any of numerous CMake tutorials for further documentation, but this tutorial should be enough to get mlpack built and installed.

First, unpack the mlpack source and change into the unpacked directory. Here we use mlpack-x.y.z where x.y.z is the version.

$ tar -xzf mlpack-x.y.z.tar.gz
$ cd mlpack-x.y.z

Then, make a build directory. The directory can have any name, not just 'build', but 'build' is sufficient.

$ mkdir build
$ cd build

The next step is to run CMake to configure the project. Running CMake is the equivalent to running ./configure with autotools. If you run CMake with no options, it will configure the project to build with no debugging symbols and no profiling information:

$ cmake ../

You can specify options to compile with debugging information and profiling information:

$ cmake -D DEBUG=ON -D PROFILE=ON ../

Options are specified with the -D flag. A list of options allowed:

DEBUG=(ON/OFF): compile with debugging symbols
PROFILE=(ON/OFF): compile with profiling symbols
ARMA_EXTRA_DEBUG=(ON/OFF): compile with extra Armadillo debugging symbols
BOOST_ROOT=(/path/to/boost/): path to root of boost installation
ARMADILLO_INCLUDE_DIR=(/path/to/armadillo/include/): path to Armadillo headers
ARMADILLO_LIBRARY=(/path/to/armadillo/libarmadillo.so): Armadillo library

Other tools can also be used to configure CMake, but those are not documented here.

Once CMake is configured, building the library is as simple as typing 'make'. This will build all library components as well as 'mlpack_test'.

$ make

You can specify individual components which you want to build, if you do not want to build everything in the library:

$ make pca allknn allkfn

If the build fails and you cannot figure out why, register an account on Github and submit an issue; the mlpack developers will quickly help you figure it out:

mlpack on Github

Alternately, mlpack help can be found in IRC at #mlpack on irc.freenode.net.

If you wish to install mlpack to /usr/include/mlpack/ and /usr/lib/ and /usr/bin/, once it has built, make sure you have root privileges (or write permissions to those two directories), and simply type

$ make install

As an example to check if install is working fine,type

$ allknn --h

to get the help for the k nearest neigbours implementation of mlpack.

If instead you get an error about problem of loading the .so files then add line

export LD_LIBRARY_PATH=/usr/local/lib

to .bashrc file.

You can now run the executables by name; you can link against mlpack with -lmlpack and the mlpack headers are found in /usr/local/include/mlpack/.

Running mlpack programs

After building mlpack, the executables will reside in build/bin/. You can call them from there, or you can install the library and (depending on system settings) they should be added to your PATH and you can call them directly. The documentation below assumes the executables are in your PATH.

We consider the 'allknn' program, which finds the k nearest neighbors in a reference dataset of all the points in a query set. That is, we have a query and a reference dataset. For each point in the query dataset, we wish to know the k points in the reference dataset which are closest to the given query point.

Alternately, if the query and reference datasets are the same, the problem can be stated more simply: for each point in the dataset, we wish to know the k nearest points to that point.

Each mlpack program has extensive help documentation which details what the method does, what each of the parameters are, and how to use them:

$ allknn --help

Running allknn on one dataset (that is, the query and reference datasets are the same) and finding the 5 nearest neighbors is very simple:

$ allknn -r dataset.csv -n neighbors_out.csv -d distances_out.csv -k 5 -v

The -v (--verbose) flag is optional; it gives informational output. It is not unique to allknn but is available in all mlpack programs. Verbose output also gives timing output at the end of the program, which can be very useful.

Further documentation

The documentation given here is only a fraction of the available documentation for mlpack. If doxygen is installed, you can type 'make doc' to build the documentation locally. Alternately, up-to-date documentation is available for older versions of mlpack: