Can't see numpy etc after upgrading Python on Ubuntu

[ozpeterballard at gmail.com]

OK thanks both of you. I didn't realise there was a distinction between system python and other (user/personal) python. Yes, python2.7.3 is still there in /usr/bin/python .

/usr/bin/python appears to be getting numpy and scipy from /usr/lib/python2.7/dist-packages . So I added that to PYTHONPATH and reran python (i.e. /usr/local/bin/python, which is 2.7.12). 

But now when I "import numpy" I get an error message which ends in:
 File "/usr/lib/python2.7/dist-packages/numpy/core/__init__.py", line 5, in <module>
    import multiarray
ImportError: /usr/lib/python2.7/dist-packages/numpy/core/multiarray.so: undefined symbol: PyUnicodeUCS4_AsUnicodeEscapeString

So for now I give up.

But the good news is that I have learned that my "old" python (2.7.3) is still on my machine. So for now I am renaming /usr/local/bin/python to /usr/local/bin/python2.7.12 , and going back to using python 2.7.3.