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A pythonic interface for the ROOT libraries on top of the PyROOT bindings.
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Documentation is hosted here: and mirrored here:


rootpy provides a more feature-rich and pythonic interface with the ROOT libraries on top of the existing PyROOT bindings.

More specifically, rootpy provides:

  • easier manipulation of trees, histograms, graphs, cuts, and TVector/TLorentzVectors. rootpy provides classes that inherit from these ROOT classes and implement the Python arithmetic operators.
  • an easy way to create and read ROOT TTrees and a mechanism for defining objects and collections of objects whose attributes are TTree branches. You may also decorate TTree objects with additional methods and attributes. See examples/tree.
  • easy navigation through TFiles. rootpy wraps TFile and implements the natural naming convention so that objects may be retrieved with myFile.someDirectory.treeName, for example.
  • an interface between ROOT and matplotlib. Don't like the way your plots look in ROOT? Simply use rootpy to plot your ROOT histograms or graphs with matplotlib instead.
  • conversion of ROOT TFiles containing TTrees into HDF5 format with PyTables.
  • conversion of TTrees into NumPy ndarrays and recarrays. Now take advantage of the many statistical and numerical packages that Python offers (NumPy, SciPy, StatsModels, use scikit-learn for machine learning instead of TMVA).
  • efficient filling of ROOT histograms from NumPy ndarrays.
  • a framework for parallelizing processes that run over many TTrees.
  • roosh, a Bash-like shell environment for the ROOT TFile.
  • a collection of useful command line scripts: root-ls, root-cp, root-tree-ls, and others.


  • Python 2.6 or 2.7
  • ROOT 2.28+ with PyROOT enabled

The following dependencies are optional:

rootpy is developed and tested on Linux and Mac. At the moment python 3 is not supported, but see this issue for progress.

Getting the Latest Source

Clone the repository with git:

git clone git://

or checkout with svn:

svn checkout


svn does not checkout git submodules so you will end up with an incomplete rootpy.

Manual Installation

If you have obtained a copy of rootpy yourself use the script to install.

To install in your home directory:

python install --user

To install system-wide (requires root privileges):

sudo python install

To install optional requirements (matplotlib, NumPy, etc.):

pip install -U -r optional-requirements.txt

To install roosh requirements:

pip install -U -r roosh-requirements.txt

To disable building the extension modules, do this before installing:

export ROOTPY_NO_EXT=1

Automatic Installation

The easiest way to install a released version of rootpy is with pip.

To install in your home directory:

pip install --user rootpy

To install system-wide (requires root privileges):

sudo pip install rootpy


This will install the latest version of rootpy on PyPI which may be lacking many new unreleased features.


If you installed rootpy into your home directory with the --user option above, add ${HOME}/.local/bin to your ${PATH} if it is not there already (put this in your .bashrc):

export PATH=${HOME}/.local/bin${PATH:+:$PATH}


Please post on the list if you have ideas or contributions. Feel free to fork rootpy on GitHub and later submit a pull request.

rootpy needs attention in these areas:

  • Documentation
  • Tutorials
  • A website displaying the above (currently under construction here:
  • Unit testing
  • Brenchmarking performance (i.e. Tree read/write)
  • Cleaning up the existing code
  • Finishing the server/worker code for distributed computing across multiple nodes
  • Creation of a TBrowser alternative using PyGTK
  • Creation of a framework for managing datasets (using SQLite as a back-end? with revision control?)
  • Additional features anyone would like to implement

Have Questions or Found a Bug?

Post your questions on and use the tag rootpy (this tag does not exist yet, but if you have a reputation of at least 1500 then please create it).

Think you found a bug? Open a new issue here:

Also feel free to post questions or follow discussion on the developers ( or users ( lists.

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