Broken Python 2.6 installation on Ubuntu Linux 8.04

[John Ladasky]

Hello everyone,

I've posted this same question over on ubuntuforums.org, so I'm trying
to get help in all of the logical places.

I'm running Ubuntu Linux 8.04 (Hardy) on a fairly new x86 box, with
two hard disks in a software RAID 1 configuration.

Hardy comes with Python 2.5 as a standard package, but not 2.6.  I
would really like to have the "combinations" function that is included
with itertools in Python 2.6.  I tried writing a combinations function
of my own, but it's SLOW and uses a HUGE amount of memory.

So, in my case the Linux Synaptic Package Manager cannot be used to
install Python 2.6.  I therefore attempted a manual installation.  I
downloaded the Linux tarball for Python 2.6 from python.org.  I
followed the installation instructions, and they appeared to execute
fine.  But when I started IDLE, I still had Python 2.5.  No good.

I do most of my editing in SCIte.  Apparently SCIte knows that I have
Python 2.6, and is trying to use it. Alas, my programs depend on extra
Python packages such as biopython, numpy and matplotlib. My Python 2.6
distro does not have these yet. None of my programs will run from
SCIte!

Looking down into the details of the install, I've discovered that
Hardy placed the Python 2.4 and 2.5 executables in /usr/bin.  My
Python 2.6 installation ended up in /usr/local/bin.  This may be
contributing to my problems.

Given the mess I've made by trying to just install plain-old Python, I
don't know whether I should attempt to back out, or to press on. Can I
convince IDLE to connect to Python 2.6?  How do I manually install
site packages?

Alternately, I COULD upgrade my Ubuntu Linux to 9.4 (Jaunty) or 9.10
(Karmic).  Python 2.6 comes standard with both of these.  But this is
why I mentioned that my storage is RAID1.  Apparently, upgrading with
RAID present is a serious headache.  The Linux wizards are supposed to
be fixing these problems in the next release, due in April.  I could
wait, I suppose.

In the mean time, I may have to uninstall Python 2.6 and get my 2.5
running again.  I have not found any instructions for how to do that.

Help!