What is the best way to install python 2 on OS X?

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开发者_开发百科 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.

I use brew to install all my libraries/compilers/interpreters.

To install python try this:

brew install python

Then add Python's binaries directory to your $PATH in your ~/.profile:

export PATH=`brew --prefix python`/bin:$PATH

I'd recommend you to install pip, virtualenv and virtualenvwrapper to have better control over your environment too.

Have you tried ActivePython?

It includes a package manager (PyPM) that, by default, installs into your home directory (eg: ~/Library/Python/2.7). Main scripts get symlinked in /usr/local/bin; use the included pythonselect to set the active Python version.

You don't have to bother installing .dmg packages, as PyPM is a binary package manager ... therefore you can install non-pure Python packages like NumPy without having to compile things yourself.

ActivePython can use Apple's Tcl/Tk or, if installed, ActiveTcl.

A "simplest, most general approach" in your documentation could be:

1. Install ActivePython 2.7
2. Open Terminal and type pypm-2.7 install matplotlib ipython

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

In almost all cases, the best python to use is the one from http://python.org/. It sets up the paths correctly and doesn't overwrite anything. DMG package installs usually work automatically, as does python setup.py install, and it's not too hard to get setuptools to work. If you want per-user installs, it is easy to set up .pydistutils.cfg and python automatically recognizes the path install_lib = ~/Library/Python/$py_version_short/site-packages

An addendum regarding the usage of brew:

Since some time, brew install python will install python3.

If you intend to install python2, you want to use

brew install python@2

It is perfectly fine to install both python and python3 using brew!

Here is an old post that answers your questions too.

In general it is not a problem at all to have more than one python installation on your machine. You just have to watch out which one you are calling on the command line.

>> which python 

... helps to identify where your python binary is located. The original Mac OS X python is usually at "/usr/bin/python"

I personally use the MacPorts python installation. It also supports you with the installation of modules. (see link above)

I have 4 versions of python on my MacBook Pro. 2 from the original install of OS X 10.6 and a subsequent update, then self installed copies of python 2.7 and 3.2. You can update the python command to point at any of the versions. They all install in separate directories and cause no problems with each other.

I'm not sure what will happen when you install from a .dmg file. I believe it will simply use whatever version python points to.

This post on superuser.com answers your questions on changing default paths.