At the terminal, enter:

which python2.7

which should return the full path to the executable, e.g.:

[steve@ando ~]$ which python2.7
/usr/local/bin/python2.7

My system uses Python 2.4 as the system Python, but I prefer to use
Python 2.7 as my default. So I have this command in my .bashrc file:

alias python='python2.7'

which means that *for me*, "python" launches Python 2.7, but when system
tools call "python" they still see the version they are expecting.

If your shell is something other than bash, you may need to use a
different rc file.

Did any of this make sense to you? If anything was unclear, please don't
hesitate to ask.

Most of what you wrote made very good sense, yes.

Umm, I didn't usa altinstall - should I (and can I) go back? [In hindsight I do like your solution to the versopns a lot more, yes]

Without more detail about what you did – detail which you perhaps can't
provide, since it's like asking “where did you last see the thing you
lost” – there's not much more we can do but guess.

You could try following the install instructions again, paying careful
attention to what might go wrong. Either something will go wrong, and
you'll be paying close enough attention to report it; or nothing will go
wrong, and you'll be able to use the version you want.

Good hunting.

   which python

should tell you the path to the python you are invoking.  It doesn't
appear to be an Apple-supplied one or a python.org one, BTW.

The installers from python.org by default modify
your .bashrc file to put
/Library/Frameworks/Python.framework/Versions/2.7/bin
at the front of your shell's search path.

However, that only affects windows opened after the install
(unless you use "source ~/.bashrc" to read the new setting
into a pre-existing window).

What happens if you type:
/Library/Frameworks/Python.framework/Versions/2.7/bin/python ?

If yours isn't, you could try looking in finder at the
disk you installed Python to, and see if it has a top-level
folder named "Library", containing "Frameworks", etc.

If you find a "Python.framework" under /System/Library
that's the one that ships with MacOS.

Hope this helps,

The windows faq is outdated wrt PEP397.  An up to date version is
available here http://docs.python.org/dev/using/windows.html

--
Cheers.

First, if none of the hints you've received earlier have gotten you going.  Maybe the thing is to resort to a bigger hammer.  In a terminal window:

$sudo find / -name Python -print<return>

This will search the entire file system for all the files named Python and will ask for your admin password so it can search in directories owned by root.  (It may also generate quite a bit of output, so you might want to capture it in a file.)  In any case, this will take several minutes and while it is running, you can be checking a couple of other things.  OS X doesn't use a .bashrc file by default (you can make it do so if you want, but that's extra work right now).  It uses .login and then .profile to set up your python path _if_ you've used the installer from python.org.

So, look to see if you have a .profile in your ~ directory.  If so, then you're using (or have used at some point in the past) an installer from python.org.
It should have an entry that looks something like the following:

# Setting PATH for Python 2.7
# The orginal version is saved in .profile.pysave
PATH="/Library/Frameworks/Python.framework/Versions/2.7/bin:${PATH}"
export PATH

Note the distinction between this path and the one from Apple.  The python that ships from Apple is in /System/Library/Frameworks…

Do NOT touch the one from Apple.  Apple uses it for some of its housekeeping operations and you want it to stay just as Apple installed it.

When you finally find the Python 2.7 in the output from the "find" command, you can edit your .login (if you don't have a .profile) or edit .profile if you do.

      sudo find / -name python -print

    find / -name python > /tmp/pythons.txt 2> /dev/null

The 2>/dev/null bit throws away warnings about permission problems
and the like.

Alternatively, you can cut down the output like so:

    find / -name python -print | grep bin/python

That will only report pythons found in directories named "bin".
On my laptop, that cuts the output down to:

/Library/Frameworks/Python.framework/Versions/2.7/bin/python
/opt/local/bin/python
/opt/local/Library/Frameworks/Python.framework/Versions/2.6/bin/python
/opt/local/Library/Frameworks/Python.framework/Versions/2.7/bin/python
/System/Library/Frameworks/Python.framework/Versions/2.5/bin/python
/System/Library/Frameworks/Python.framework/Versions/2.6/bin/python
/usr/bin/python
/usr/local/bin/python

Those are all valid python interpreters, or wrappers for same.

I don't think there is a shell that can read both .login and .profile
since .login typically uses C shell syntax and .profile uses Bourne
shell syntax.

If you're not sure which shell you have, type

    echo $SHELL

at the shell prompt.

To eliminate the output from TimeMachine (assuming it is using an external drive or a TimeCapsule), add one more option to the find command:

$ sudo find -x / -name python -print  (or follow his directions for piping to a file).

The -x option prevents find from descending into a volume with a different device number from the one you started on.

Can you run the install procedure again and capture the output?