Python on the ITM platform

Python installation: overview

The ITM platform includes a Python installation, with

• a number of standard libraries for scientific computing (NumPy, SciPy, matplotlib, ...)
• a UAL interface for reading and writing CPOs from/to the ITM database
• ITM-specific libraries for handling CPOs, the general grid description and CPO-specific visualization tools

The following Python versions are available: 2.5.1, 2.6.7.

The current default Python version is 2.5.1.

Documentation, tutorials and training material

To be added...

Switching between Python versions

The "select_python" command is provided to allow users to quickly switch between different Python versions. It takes care of correctly setting up the Python environment, including all UAL data version specific Python components (modules, scripts, ...).

Usage:

source $ITMSCRIPTDIR/select_python [PYTHONVERSION]

or, using an alias provided in the default ITM environment

set_python [PYTHONVERSION]

When running the command from a login script (e.g. your ~/.cshrc file), the following is recommended:

source $ITMSCRIPTDIR/select_python [PYTHONVERSION]  > /dev/null

• PYTHONVERSION can be one of "2.5", "2.6" or "default" (the current default is 2.5).
• If it is ommitted, any previously selected Python version is kept. If no Python version was previously selected, the default version is selected.
• If an ITM data version was selected (by running the ITMv1 script), the Python environment is set up to include UAL-specific components. If no data version is currently selected, the UAL-specific components are not included in the environment.

Example: to automatically switch to Python 2.6 when logging in, add the following line in your ~/.cshrc file:

source $ITMSCRIPTDIR/select_python 2.6 > /dev/null

Known issues when switching between Python versions

• Not all scripts and packages are available for all versions. Be aware of this when switching between versions.
• ipython

  ipython keeps a local database to store settings in your home directory at ~/.ipython, the format of which might be incompatible between versions. If you get error messages when starting ipython, move your ipython directory (mv ~/.ipython ~/.ipython_old) or delete it.

• matplotlib
  • matplotlib keeps a local database to store settings in your home directory at ~/.matplotlib, the format of which might be incompatible between versions. If you get error messages when running a script that uses matplotlib, move your matplotlib directory (mv ~/.matplotlib ~/.matplotlib_old) or delete it.
  • Different versions of matplotlib are installed for the different Python versions. This can lead to some plotting scripts not working properly. Typically matplotlib will give warnings when deprecated functions are used.

Details

select_python modifies the environment variables PATH, PYTHONPATH, LD_LIBRARY_PATH and PYTHONVERSION. PYTHONVERSION is set to the currently selected version.

Development tools

• Eclipse & PyDev plugin

  A fully integrated IDE, including a source debugger. It's available on the gateway ('eclipse' command).

  Documentation: PyDev Website, PyDev Manual

Available Python modules

• SciPy

  Documentation (pick the right version)

  Python 2.5: version 0.7.0
  Python 2.6: version 0.10.0

• NumPy

  Documentation (pick the right version)

  Python 2.5: version 1.2.1
  Python 2.6: version 1.6.1

• matplotlib

  Documentation (for the latest version)

  If you need the documentation for 0.99.3, please contact ISIP.

  Python 2.5: version 0.99.3
  Python 2.6: version 1.2.x

• ipython

  Documentation (pick the right version)

  Python 2.5: version 0.8.4
  Python 2.6: version 0.12

Installation details

Directory layout

• select_python script

  $ITMSCRIPTDIR/select_python

• Python installations

  $SWITMDIR/python/python2.5.1
  $SWITMDIR/python/python2.6.7
  

• Standard packages (NumPy, SciPy, matplotlib, ...)

  /afs/.efda-itm.eu/project/switm/python/python_pk.2.5.1
  $SWITMDIR/python/python_pk.2.6/lib/python2.6/site-packages

• ITM-specific packages (UAL, ...)
  • Python UAL interface

    $SWITMDIR/ual/$DATAVERSION/python_pk.$PYTHONVERSION

  • ITM Visualization Library

    $SWITMDIR/itmvis/$DATAVERSION/python_pk.$PYTHONVERSION