Question

In python 2.7, by using

 from __future__ import division, print_function

I can now have print(1/2) showing 0.5.

However is it possible to have this automatically imported at python startup ?

I tried to use the sitecustomize.py special module but the inport is only valid inside the module and not in the shell.

As I’m sure people will ask why I need that : teaching Python to teenagers I noticed that the integer division was not easy for them so we decided to switch to Python 3. However one of the requirement of the course was to be able to plot function and Matplotlib is pretty good but only valid for Python 2.7.

So my idea was to use a custom 2.7 installation…not perfect but I don’t have a better idea to have both Matplotlib and the new “natural” division “1/2=0.5”.

Any advice or maybe a Matplotlib alternative that is working on python 3.2 ?

Answer 1

matplotlib on python 3 is closer than you may think: https://github.com/matplotlib/matplotlib-py3; http://www.lfd.uci.edu/~gohlke/pythonlibs/#matplotlib.

Why not use PYTHONSTARTUP instead of sitecustomize.py?

localhost-2:~ $ cat startup.py 
from __future__ import print_function
from __future__ import division
localhost-2:~ $ export PYTHONSTARTUP=""
localhost-2:~ $ python
Python 2.7.2 (v2.7.2:8527427914a2, Jun 11 2011, 15:22:34) 
[GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> 1/2
0
>>> print("fred",end=",")
  File "<stdin>", line 1
    print("fred",end=",")
                    ^
SyntaxError: invalid syntax
>>> ^D
localhost-2:~ $ export PYTHONSTARTUP=startup.py
localhost-2:~ $ python
Python 2.7.2 (v2.7.2:8527427914a2, Jun 11 2011, 15:22:34) 
[GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> 1/2
0.5
>>> print("fred",end=",")
fred,>>>