Installing silx in a virtualenv¶

This step-by-step guide explains how to install silx in a virtualenv.

Prerequisites¶

This guide assumes that your system meets the following requirements:

a version of python compatible with silx is installed (python 2.7 or python >= 3.5)

the pip installer for python packages is installed

the Qt and PyQt libraries are installed (optional, required for using silx.gui)

Installation procedure¶

Install vitrualenv¶

pip install virtualenv --user

Note

This step is not required for recent version of Python 3. Virtual environments are created using a builtin standard library, venv. On Debian platforms, you might need to install the python3-venv package.

Create a virtualenv¶

The files required by a virtual environment are created in a new folder with the same name as the virtualenv. So make sure you are in a directory in which you have write permissions.

In this tutorial we use a folder venvs in our home directory, and we create a virtual environment named silx_venv

cd
mkdir -p venvs
cd venvs
virtualenv silx_venv

A virtualenv contains a copy of your default python interpreter with a few tools to install packages (pip, setuptools).

To use a different python interpreter, you can specify it on the command line. For example, to use python 3.4:

virtualenv -p /usr/bin/python3.4 silx_venv

But for python 3 you should use the builtin venv module:

python3 -m venv /path/to/new/virtual/environment

Note

If you don’t need to start with a clean environment and you don’t want to install each required library one by one, you can use a command line option to create a virtualenv with access to all system packages: --system-site-packages

Activate a virtualenv¶

A script is provided in your virtualenv to activate it.

source silx_venv/bin/activate

After activating your new virtualenv, this python interpreter and its package tools are used, instead of the ones from the system.

Any libraries you will install or upgrade will be inside the virtual environment, and will not affect the rest of system.

To deactivate the virtual environment, just type deactivate.

Upgrade pip¶

After activating silx_venv, you should upgrade pip:

python -m pip install --upgrade pip

Upgrade setuptools and wheel¶

Upgrading the python packaging related libraries can make installing the rest of the libraries much easier.

pip install setuptools --upgrade
pip install wheel --upgrade

Install build dependencies¶

The following command installs libraries that are required to build and install silx:

pip install numpy cython

Install optional dependencies¶

The following command installs libraries that are needed by various modules of silx:

pip install matplotlib fabio h5py

The next command installs libraries that are used by the python modules handling parallel computing:

pip install pyopencl mako

Install pyqt¶

If your python version is 3.5 or newer, installing PyQt5 and all required packages is as simple as typing:

pip install PyQt5

For previous versions of python, there are no PyQt wheels available, so the installation is not as simple.

The simplest way, assuming that PyQt is installed on your system, is to use that system package directly. For this, you need to add a symbolic link to your virtualenv.

If you want to use PyQt4 installed in /usr/lib/python2.7/dist-packages/, type:

ln -s /usr/lib/python2.7/dist-packages/PyQt4 silx_venv/lib/python2.7/site-packages/
ln -s /usr/lib/python2.7/dist-packages/sip.so silx_venv/lib/python2.7/site-packages/

Install silx¶

pip install silx

To test silx, open an interactive python console. If you managed to install PyQt or PySide in your virtualenv, type:

python

If you don’t have PyQt, use:

WITH_QT_TEST=False python

Run the test suite using:

>>> import silx.test
>>> silx.test.run_tests()