Installation

Installing pygnuastro

Python packages can be distributed in mainly two ways, a built distribution and a source distribution. Built distributions are available in the form of wheels. Wheels offer a faster installation, smaller size and better maintainability. By default pip will always choose a wheel file over sdist file, unless you are using a very recent version of Python, if a new version of pygnuastro has just been released, or if you are building pygnuastro for a platform that is not common. Note that in this case you will need a C compiler (e.g., gcc or clang) and the external dependencies to be installed (see Building from source below) for the installation to succeed.

Using pip (PyPI)

To install pygnuastro with pip, run:

pip install pygnuastro

If you want to make sure none of your existing dependencies get upgraded, you can also do:

pip install pygnuastro --no-deps

If you get a PermissionError this means that you do not have the required administrative access to install new packages to your Python installation. In this case you may consider using the --user option to install the package into your home directory. You can read more about how to do this in the pip documentation.

Alternatively, if you wish to use pygnuastro in a project, or wish to isolate the pygnuastro package for a different purposes, consider installing it in a virtual environment instead.

Do not install pygnuastro using sudo unless you are fully aware of the risks.

Testing an Installed pygnuastro

TBA after adding a test module. Currently pytest can be used by running pytest in the top of the pyGnuastro source after having installed pyGnuastro.

Building from Source

Warning

Source distribution installtions are not recommended since they require the user to have all the dependencies of pyGnuastro also installed.

The source distribution of pygnuastro is available in the form of a tar and zip files. The source distribution contains the projects source tree, which you can find on GitHub. In order to install the package

Requirements

pygnuastro has the following strict requirements:

• Python 3.6 or later

• Numpy 1.23 or later

Prerequisites

You will need a compiler suite and the development headers for Python in order to build pygnuastro. Since pyGnuastro is a wrapper over the Gnuastro Library the other essential requirement is Gnuastro. It can be either built from source or installed using a supported package manager . To know more about how to build and install Gnuastro go through the Installation chapter in the Gnuastro Book

Prerequisites for Linux

On Linux, using the package manager for your distribution will usually be the easiest route to making sure you have the prerequisites to build pygnuastro. In order to build from source, you will need the Python development package for your Linux distribution, as well as pip.

For Debian/Ubuntu:

sudo apt-get install python3-dev python3-numpy-dev python3-setuptools

For Fedora/RHEL:

sudo yum install python3-devel python3-numpy python3-setuptools

Prerequisites for Mac OS X

On MacOS X you will need the XCode command line tools which can be installed using:

xcode-select --install

Follow the onscreen instructions to install the command line tools required. Note that you do not need to install the full XCode distribution (assuming you are using MacOS X 10.9 or later).

The instructions for building NumPy from source are a good resource for setting up your environment to build Python packages.

Obtaining the Source Packages

Source Packages

The latest stable source package for pygnuastro can be downloaded here.

Development Repository

The latest development version of pygnuastro can be cloned from GitHub using this command:

git clone https://github.com/Jash-Shah/pyGnuastro.git

Building and Installing

To build and install pygnuastro (from the root of the source tree) assuming you have all the Prerequisites installed:

python3 setup.py build -I/path/to/gnuastro-installed-headers -L/path/to/gnuastro-installed-lib
python3 setup.py install

Note

Since pygnuastro depends on Gnuastro, while building the python package, we need to provide the include path(-I) and the library path(-L) (See Directory Options) to link to the Gnuastro Library and its installed headers. The include path should be the path of the dirctory where the Gnuastro Library headers are installed(usually /usr/local/include). The library path(usually /usr/local/lib) is the path to the directory where the Gnuastro Library (libgnuastro.so) is located. See the Installation Directory chapter in the Gnuastro Book for more information on how and where to install Gnuastro.

If Gnuatro was configured with no --prefix option or with it set to /usr/local/include then no flags need to be passed to the python3 setup.py build command.

Troubleshooting

If you get an error mentioning that you do not have the correct permissions to install pygnuastro into the default site-packages directory, you can try installing with:

python3 setup.py install --user

which will install into a default directory in your home directory.

For Developers

The pygnuastro wheels ship with the external dependencies(Gnuastro library). This is done, so that users don’t need to install and setup Gnuastro and can just run pip install pygnuastro.

However, this means deveopers who would like to tinker with the pygnuastro code are tied with the version of Gnuastro in the wheel file. This can lead to scenarios where a deveoper might want to, say add a python wrapper for a Gnuastro Library fucntion. However, the version of the Gnuastro Library shipped in the wheel file does not have that fucntion yet.

The best way to overcome this for developers, is to use the Building from Source.