# Installing igraph

## Binary package (recommended)

It is recommended to install a binary package that includes both C core and Python interface. You can choose either of PyPI or Conda. Linux users can also use their package manager.

### PyPI

PyPI has installers for Windows, Linux, and macOS. We aim to provide binary packages for the three latest minor versions of Python 3.x.

To install the Python interface of igraph globally, use the following command (you might need administrator/root privileges):

    $ pip install igraph

If you prefer to install igraph in a user folder using a virtual environment, use the following commands instead:

    $ python -m venv my_environment
    $ source my_environment/bin/activate
    $ pip install igraph

As usual, if you do not want to activate the virtualenv, you can call the `pip` executable in it directly:

    $ python -m venv my_environment
    $ my_environment/bin/pip install igraph

### Conda

Packages are kindly provided by conda-forge:

    $ conda install -c conda-forge python-igraph

Like virtualenv, Conda also offers virtual environments. If you prefer that option:

    $ conda create -n my_environment
    $ conda activate my_environment
    $ conda install -c conda-forge python-igraph

### Package managers on Linux and other systems

igraph’s Python interface and its dependencies are included in several package management systems, including those of the most popular Linux distributions (Arch Linux, Debian and Ubuntu, Fedora, etc.) as well as some cross-platform systems like NixPkgs or MacPorts.

Note

igraph is updated quite often: if you need a more recent version than your package manager offers, use `pip` or `conda` as shown above. For bleeding-edge versions, compile from source (see below).

## Compiling igraph from source

You might want to compile igraph to test a recently added feature ahead of release or to install igraph on architectures not covered by our continuous development pipeline.

Note

In all cases, the Python interface needs to be compiled against a matching version of the igraph core C library. If you used `git` to check out the source tree, `git` was probably smart enough to check out the matching version of igraph’s C core as a submodule into `vendor/source/igraph`. You can use `git submodule update --init --recursive` to check out the submodule manually, or you can run `git submodule status` to print the exact revision of igraph’s C core that should be used with the Python interface.

### Compiling using pip

If you want the development version of igraph, call:

    $ pip install git+https://github.com/igraph/python-igraph

`pip` is smart enough to download the sources from Github, initialize the submodule for the igraph C core, compile it, and then compile the Python interface against it and install it. As above, a virtual environment is a commonly used sandbox to test experimental packages.

If you want the latest release from PyPI but prefer to (or have to) install from source, call:

    $ pip install --no-binary ':all:' igraph

Note

If there is no binary for your system anyway, you can just try without the `--no-binary` option and obtain the same result.

### Compiling step by step

This section should be rarely used in practice but explains how to compile and install igraph step by step from a local checkout, i.e. _not_ relying on `pip` to fetch the sources. (You would still need `pip` to install from source, or a PEP 517-compliant build frontend like build to build an installable Python wheel.

First, obtain the bleeding-edge source code from Github:

    $ git clone https://github.com/igraph/python-igraph.git

or download a recent release from PyPI or from the Github releases page. Decompress the archive if needed.

Second, go into the folder:

    $ cd python-igraph

(it might have a slightly different name depending on the release).

Third, if you cloned the source from Github, initialize the `git` submodule for the igraph C core:

    $ git submodule update --init

Note

If you prefer to compile and link igraph against an existing igraph C core, for instance the one you installed with your package manager, you can skip the `git` submodule initialization step. If you downloaded a tarball, you also need to remove the `vendor/source/igraph` folder because the setup script will look for the vendored igraph copy first. However, a particular version of the Python interface is guaranteed to work only with the version of the C core that is bundled with it (or with the revision that the `git` submodule points to).

Fourth, call `pip` to compile and install the package from source:

    $ pip install .

Alternatively, you can call `build` or another PEP 517-compliant build frontend to build an installable Python wheel. Here we use pipx to invoke `build` in a separate virtualenv:

    $ pipx run build

### Testing your installation

Use `tox` or another standard test runner tool to run all the unit tests. Here we use pipx <https://pypa.github.io/pipx/>`_ to invoke `tox`:

    $ pipx run tox

You can also call `tox` directly from the root folder of the igraph source tree if you already installed `tox` system-wide:

    $ tox

## Troubleshooting

### Q: I am trying to install igraph on Windows but am getting DLL import errors

A: The most common reason for this error is that you do not have the Visual C++ Redistributable library installed on your machine. Python’s own installer is supposed to install it, but in case it was not installed on your system, you can download it from Microsoft.

### Q: I am trying to use igraph but get errors about something called Cairo

A: igraph by default uses a third-party called Cairo for plotting. If Cairo is not installed on your computer, you might get an import error. This error is most commonly encountered on Windows machines.

There are two solutions to this problem: installing Cairo or, if you are using a recent versions of igraph, switching to the `matplotlib` plotting backend.

1. Install Cairo: As explained here, you need to install Cairo headers using your package manager (Linux) or homebrew (macOS) and then:

    $ pip install pycairo

To check if Cairo is installed correctly on your system, run the following example:

    >>> import igraph as ig
    >>> g = ig.Graph.Famous("petersen")
    >>> ig.plot(g)

If PyCairo was successfully installed, this will display a Petersen graph.

2. Switch to matplotlib: You can configure igraph to use matplotlib instead of Cairo. First, install it:

    $ pip install matplotlib

To use matplotlib for a single plot, create a `matplotlib.figure.Figure` and `matplotlib.axes.Axes` beforehand (e.g. using `matplotlib.pyplot.subplots()`):

    >>> import matplotlib.pyplot as plt
    >>> import igraph as ig
    >>> fig, ax = plt.subplots()
    >>> g = ig.Graph.Famous("petersen")
    >>> ig.plot(g, target=ax)
    >>> plt.show()

To use matplotlib for a whole session/notebook:

    >>> import matplotlib.pyplot as plt
    >>> import igraph as ig
    >>> ig.config["plotting.backend"] = "matplotlib"
    >>> g = ig.Graph.Famous("petersen")
    >>> ig.plot(g)
    >>> plt.show()

To preserve this preference across sessions/notebooks, you can store it in the default configuration file used by igraph:

    >>> import igraph as ig
    >>> ig.config["plotting.backend"] = "matplotlib"
    >>> ig.config.save()

From now on, igraph will default to matplotlib for plotting.