Installing igraph ¶
- Installing igraph
This chapter describes how to install the C core of igraph and its Python bindings on Windows, macOS, and GNU/Linux.
Which igraph is right for you?¶
igraph is primarily a library written in C. It is not a standalone program, nor it is a pure Python package that you can just drop in your Python path. Therefore, if you would like to use igraph’s functionality in Python, you must install a few packages. Do not worry, though, there are precompiled packages for the major operating systems. Precompiled packages are often called binary packages, while the raw source code is usually referred to as the source package.
In general, you should almost always opt for the binary package unless a binary package is not available for your platform or you have some local modifications that you want to incorporate into igraph’s source. Installation from a binary package tells you how to install igraph from a precompiled binary package on various platforms. Compiling python-igraph from source tells you how to compile igraph from the source package.
Installation from a binary package¶
Installing igraph from the Python Package Index¶
To ensure getting the latest binary release of igraph’s Python interface, it is recommended that you install it from the Python Package Index (PyPI), which has installers for Windows, Linux, and macOS. Currently there are binary packages for Python 2.7, and Python 3.5 through 3.8, but note that support for Python 2.7 will be discontinued with the version 0.9.0 release of igraph’s Python interface.
To install python-igraph globally, use the following command (you probably need administrator/root priviledges):
$ pip install python-igraph
Many users like to install packages into a project-specific virtual environment. A variation of the following commands should work on most platforms:
$ python -m venv venv $ source venv/bin/activate $ pip install python-igraph
Alternatively, if you do not want to activate the virtualenv, you can call the pip executable in it directly:
$ python -m venv venv $ venv/bin/pip install python-igraph
The unit tests of python-igraph are implemented with the standard unittest module so you can run them like this from your virtualenv:
$ python -m unittest discover
As usual, you can also do this without activating the virtualenv:
$ venv/bin/python -m unittest discover
Installing igraph via Conda¶
$ conda install -c conda-forge python-igraph
To test the installed package, launch Python and run the following:
>>> import igraph.test >>> igraph.test.run_tests()
The above commands run the bundled test cases to ensure that everything is fine with your igraph installation.
igraph on Windows¶
TODO: Check if Windows still requires special steps to get PyCairo running.
Graph plotting in igraph is implemented using a third-party package called Cairo. If you want to create publication-quality plots in igraph on Windows, you must also install Cairo and its Python bindings. The Cairo project does not provide pre-compiled binaries for Windows, but Christoph Gohlke maintains a site containing unofficial Windows binaries for several Python extension packages, including Cairo. Therefore, the easiest way to install Cairo on Windows along with its Python bindings is simply to download it from Christoph’s site. Make sure you use an installer that is suitable for your Windows platform (32-bit or 64-bit) and the version of Python you are using.
After running the installer, you can launch Python again and check if it worked:
>>> import igraph as ig >>> g = ig.Graph.Famous("petersen") >>> ig.plot(g)
If PyCairo was successfully installed, this will display a Petersen graph.
igraph on macOS¶
Graph plotting in igraph is implemented using a third-party package called Cairo. If you want to create publication-quality plots in igraph on macOS, you must also install Cairo and its Python bindings. The Cairo project does not provide pre-compiled binaries for macOS, but the Homebrew package manager <https://brew.sh/>, so you can use it to install Cairo. After installing Homebrew itself, you can run:
$ brew install cairo
After installing Cairo, launch Python and check if it worked:
>>> import igraph as ig >>> g = ig.Graph.Famous("petersen") >>> ig.plot(g)
If Cairo was successfully installed, this will display a Petersen graph.
igraph on Linux¶
igraph’s Python interface and its dependencies have been packaged for most popular Linux distributions, including Arch Linux, Debian, Fedora, GNU Guix, NixOS, and Ubuntu. python-igraph and its underlying igraph C core are usually in two different packages, but your package manager should take care of that dependency for you.
Compiling python-igraph from source¶
python-igraph binds itself into the main igraph library using some glue code written in C, so you’ll need both a C compiler and the library itself. Source tarballs of python-igraph obtained from PyPI already contain a matching version of the C core of igraph.
There are two common scenarios to compile python-igraph from source:
Your would like to use the latest development version from Github, usually to try out some recently added features
The PyPI repository does not include precompiled binaries for your system. This can happen if your operating system is not covered by our continuous development.
Both will be covered in the next sections.
Compiling using pip¶
If you want the development version of python-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 python-igraph 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:’ python-igraph
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 python-igraph step by step without pip.
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 <https://pypi.org/project/python-igraph/#files> or from the Github releases page <https://github.com/igraph/python-igraph/releases/>. 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
If you prefer to compile and link python-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 python-igraph 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 the standard Python setup.py script, e.g. for compiling:
$ python setup.py build
(press Enter when prompted). That will compile the python-igraph package in a subfolder called build/lib.<your system-your Python version>, e.g. build/lib.linux-x86_64-3.8. You can add that folder to your PYTHONPATH if you want to import directly from it, or you can call the setup.py script to install it from there:
$ python setup.py install
The setup.py script takes a number of options to customize the install location.