Installing the code

There are two methods for installing the code, both of which require conda. You can either install the code entirely with conda or install the code from source, with the dependencies still being installed via conda. Installation using conda is preferable if you simply want to run the code, while the Installation from source is necessary if you want to develop the code.

Installation using conda

A helper script exists to aid the configuration using conda. To obtain it use:

mkdir nnpdfgit
cd nnpdfgit
git clone
  • Execute the script

  • Path: the conda installer will ask to add the conda bin path to the default $PATH environment variable (by editing your .bashrc file). Confirm this unless you know that you have a specific reason not to. Note that newer versions of conda give the option of having conda available, but not any environment (which you have to enable explicitly by either having conda activate in .bashrc or typing it each time you want to use the environment). On remote machines, the addition to .bashrc should read as follows

    if shopt -q login_shell; then
        . <path-to-conda>/etc/profile.d/
        conda activate

the if condition is important because conda activate prints to the standard output, which interferes with commands like scp and rsync.

  • Note that the script may ask you to perform some actions manually ( e.g. it will not overwrite your existing conda configuration). Please pay attention to the output text of the script.

Installing the NNPDF code

After the helper script has run, navigate to the miniconda3 installation directory, by default this is ~/miniconda3, and run the command

. ./etc/profile.d/
conda activate
conda install nnpdf

This will provide functioning C++ and Python executables.

Note: The installer will set up its own version of the LHAPDF code, with its own path for storing PDFs, which can be seen running lhapdf –help. If you have an existing directory with LHAPDF grids, you may want to either move, symlink or copy them to the new path (depending on whether you want to keep around the older installation). The command for symlinking would be something like:

ln -s <old path>/share/LHAPDF/* <new path>/miniconda3/share/LHAPDF

This will avoid symlinking the existing LHAPDF configuration, which may be corrupted or incompatible. You should make sure only the grid directories are transferred if you copy or move instead.

Installation from source

If you intend to work on the NNPDF code, then building from source is the recommended installation procedure. However, you can still use conda to get all the dependencies and setup the validphys and C++ development environment. Note that the should be downloaded and run as explained above, if the user has not already done so.

  1. Create an NNPDF developer environment nnpdf-dev and install all relevant dependencies using

    conda create -n nnpdf-dev
    conda activate nnpdf-dev
    conda install --only-deps nnpdf

    Note that the user should be in the conda environment nnpdf-dev whenever they wish to work on NNPDF code. The conda environment can be exited using conda deactivate.


    If you are a macOS user, you will need to download the Mac Software Development Kit or SDK for short. This is necessary to get the correct C compiler. The anconda documentation explains in more detail why you need this file, and why they cannot include it with the compilers by default.

    You can check which version of SDK is currently being used by the Continuous integration and deployment system by checking the MACOS_SDK_URL and MACOS_SDK_FILE variables inside .travis.yml. At the time of writing this documentation, the version used is 10.9 but the user is advised to check in case the documentation has become out of sync with the CI configuration. Once you know the URL of the SDK file, you can download it from the commandline using curl, e.g.:

    curl -L -O

    You can then unpack it into your root conda directory by running

    tar xfz MacOSX10.9.sdk.tar.xz -C <path_to_root

    where you can find <path_to_root_conda_directory> by typing echo $CONDA_PREFIX when your base conda environment is activated. You should then export the following path

    export CONDA_BUILD_SYSROOT=<path_to_root_conda_directory>/MacOSX10.9.sdk

    which you may wish to write to one of your ~/.bashrc or ~/.bash_profile scripts so that the SDK is easily accessible from the shell.

  2. Install the appropriate C++ compilers using

    conda install gxx_linux-64

    macOS users should replace gxx_linux-64 with clangxx_osx-64.

  3. Ensure that the NNPDF repositories nnpdf and apfel are in the nnpdfgit directory. These are required to be able to run fits and can be obtained respectively by

    git clone
    git clone
  4. Obtain the dependencies of the code you want to build. Where to find those depends on the particular code. For example, something linking to libnnpdf will likely require pkg-config. Projects based on autotools (those that have a ./configure script) will additionally require automake and libtool. Similarly projects based on cmake will require installing the cmake package. In the case of nnpdf itself, the build dependencies can be found in <nnpdf git root>/conda-recipe/meta.yaml. We have to install the remaining ones manually:

    conda install pkg-config swig cmake

    When working on a Linux system it is currently also needed to run

    conda install sysroot_linux-64=2.17
  5. We now need to make the installation prefix point to our nnpdf-dev environment. Fortunately, when you activate the environment, the location is saved to the environment variable CONDA_PREFIX, e.g.

    $ conda activate nnpdf-dev
    $ echo $CONDA_PREFIX
  6. Navigate to the nnpdf directory obtained from the Github repository and create a directory.


    The directory name is unimportant, its role is to contain all of the build files, separately from the source files - we will refer to it as the build directory. A clean build and installation can always be achieved by deleting the contents of the build directory (or even creating a new one) and re-running cmake.

    For this example we have created a directory called conda-bld by

    nnpdf$ mkdir conda-bld
    nnpdf$ cd conda-bld

    Note that it is important that for the following step to be executed while the user is in the nnpdf-dev conda environment. The project can be built using:

    nnpdf/conda-bld$ cmake .. -DCMAKE_INSTALL_PREFIX=$CONDA_PREFIX
  7. When the user wishes to work on the NNPDF code, they should do so in, for example, /nnpdfgit/nnpdf/libnnpdf. To compile the code navigate to the build directory created above and run

    rm -r ./*
    make install

    If you are reinstalling the code using the same build directory, it is recommended to remove all files from the build directory as is shown in the example above.

Using the code with docker

We provide docker images for tag release of the code using GitHub Packages. The docker images contain a pre-configured linux environment with the NNPDF framework installed with the specific tag version. The code is installed using miniconda3.

Please refer to the download and authentication instructions from the NNPDF GitHub Packages.

In order to start the docker image in interactive mode please use docker standard syntax, for example:

docker run -it<tag_version> bash

This will open a bash shell with the nnpdf environment already activated, with all binaries and scripts from the NNPDF framework.