Question

A colleague of mine wants to use my python 2 code on his OS X (10.6) machine. My code imports several built-in python packages, including Tkinter and shelve, and also uses third-party packages, including numpy, scipy, matplotlib, and ipython.

I’ve encountered a few problems with OS X’s built-in python. (IDLE doesn’t work, for example*). I suspect I should install a more recent version of python, and a different version of Tk.

My questions:

1. Will having two different versions of python/Tk on the same machine cause problems?

2. I would like to associate the terminal commands ‘python’, ‘ipython’, and ‘easy_install’ with the more recent version of python. How should I do this?

3. When I install third-party packages like numpy using a .dmg file, how do I control which version of python numpy installs into?

4. Is there a better way to do this?

If this process goes well, I’d consider adding OS X instructions to my code’s documentation, so I’d like to boil down this process to the simplest, most general approach.

*EDIT: Also, this

EDIT: Thank you everyone for the useful answers. My colleague tried MacPorts, which seems to work well, but has a few speedbumps. First we had to install Xcode from the system install disk. This is not a fast or lightweight install (several GB). Luckily we still had the disk! Once Xcode was installed, MacPorts was easy to install. Python and the python subpackages we needed were also easy to install, but he told me this installation took several hours. Presumably this delay is due to compilation? He had an easy time setting the MacPorts python as default. However, I think we have to change the ‘Python Launcher’ application by hand, this seems to still default to the system python.

Even though he has a working system now, I’m tempted to ask him to try one of the other solutions. I’m not sure all of my code’s potential users will tolerate a multi-hour, multi-gigabyte installation.

Answer 1

Using MacPorts, you can install python 2.6, 2.7, 3.1 and 3.2 at the same time, with their own packages, without ever touching the built-in python.

numpy, scipy, matplotlib, and ipython are also available as ports for most of those python versions.

Moreover, if you install the python_select port, you’ll be able:

• to choose which one of those (plus the built-in python) is the “default” python;

• to install python packages through easy_install/pip for the “selected” python, if they’re not available as ports.

Add virtualenv to the mix, and you’ll have a very, very flexible Python development environment.

As for your questions:

Q1: with MacPorts, no. while not a frequent user, I’ve installed and used matplotlib in 2.6 and 2.7, switching between the two using python_select.

Q2: easy_install, pip, ipython will be “linked” to the python they were installed by. (but see tip 1)

Q3: it’s easier to install one of the py{26,27,xx}-numpy ports, or pip install numpy under your python_select’ed python.

Q4: well, MacPorts is the best thing I know after APT on Debian/Ubuntu… 🙂

Now, two tips if you try MacPorts:

1. MacPorts cleanly installs ports separately from the OS X installation, in an /opt/local directory, and each python version is installed in a /opt/local/Library/Frameworks/Python.framework/Versions/{2.5,2.6,2.7,...} directory. Using python_select cleanly switch the “python” command using links. BUT… the Versions/{2.5,2.6,2.7,...}/bin directory, where python scripts are installed, is not added to the PATH. Just adding: export PATH=/opt/local/Library/Frameworks/Python.framework/Versions/Current/bin:$PATH to your ~/.profile will always give you direct access to the scripts installed for the selected python.

2. to avoid bad surprises, I’ve added a echo Selected python is \"$(python_select -s)\" line to my ~/.profile, so I always know which is my currently selected python when opening a session… 🙂

Regards,

Georges