Changing Python Version

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We have a few versions of Python on the system.

  • C:\Python25epd - Enthought Python 2.5.4 is the default. It has a large list of helpful libraries that are already tested.
  • C:\Python25 - For anyone who might prefer to use the distribution of Python 2.5.1.
  • C:\Python26 - For those who need 2.6 language features. Popular numeric libraries aren't available for this release.
  • C:\Python30 - For those who need 3.0 language features. This new release changes the language. Most numeric libraries aren't available.

To choose a particular version of Python over the default, in a batch script or interactively, set the PYTHONHOME variable to the appropriate directory, then start up the command-line interpreter:

set PYTHONHOME=C:\Python30

If you fail to set PYTHONHOME, the executable will load its libraries from Python25epd.

In order to start IDLE, which is the integrated development environment (IDE) for all of the above versions of Python, enter:

%PYTHONHOME%\pythonw %PYTHONHOME%\Lib\idlelib\idle.pyw