Setting IPython on Mac OS X, Mountain Lion

Posted on by Marina Mele

This post describes how to install IPython on a Mac OS X, Mountain Lion. Step by step, it explains how to install Python, Homebrew, Virtualenv, IPython, IPython Notebook and some useful libraries like Matplotlib.

 

Mac OS X comes with Python 2.7 already installed, that can be used for learning but which might be out of date. Therefore, in this post we will explain how to install the real version of Python as well, which is better for developing.

Install XCode

Go to the Apple Store and download the free version of XCode.

Once installed, launch the application from the Launchpad menu.

In the upper menu go to Xcode –> preferences…, or alternatively use the shortcut cmd+, .

Once in the preferences window go to the Downloads tab and install the Command Line Tools, which is in the Components section.  To install it you just need to click in the right arrow.

Install Homebrew

To download and install Homebrew you need to run the following command in the Terminal:

$ ruby -e “$(curl -fsSL https://raw.github.com/mxcl/homebrew/go)”

Install Python 2.7

Now it’s very easy to install Python! just write the following in your Terminal:

$ brew install python

Unfortunately, when we run python on the Terminal, we will still be using the preinstalled Python that comes with Mac OS X. We need to change the path to point to the new version of Python.

Open (or create if you don’t have it yet) the file ~/.profile and write the following lines in it:

PATH=/usr/local/bin:/usr/local/share/python:$PATH
export PATH

The good thing about installing Python with Homebrew is that you also install pip and Distribute, which extend the packaging and installation facilities provided by the distutils in the standard library.

Virtual Environment

A good practice is to use a virtual environment to have all the packages that you are using for one project in the same folder. It is more easy to share and maintain.

To install Virtualenv:

$ sudo pip install virtualenv

Let us create a new virtual enviroment, called envipython

$ virtualenv envipython

which will create the folder envipython. To activate this environment:

$ source envipython/bin/activate

Note that the command line has changed to somehting like (envipython)$.

From now on, we will install the packages using this virtual environment. If you don’t want to use a virtual environment, you can install them in your machine with the same command lines.

Install IPython and IPython Notebook

Finally, in order to install IPython we run the following command in the Terminal:

$ pip install ipython

IPython comes with a very nice web-based notebook environment, which allows you to run python scripts in a similar way as with Mathematica or Matlab.

To install it, you will need to add the following libraries:

$ brew install freetype
$ brew install libpng
$ pip install readline
$ pip install tornado
$ brew install zeromq –universal
$ pip install pyzmq
$ pip install pygments
$ brew install pyqt
$ pip install jinja2

And that’s it! To run your IPython Notebook you only need:

$ ipython notebook

If you also want to install MathJax, which is an open source JavaScript display engine for mathematics, you need to enter to the IPython shell and type the following:

$ ipython
In [1]: from IPython.external.mathjax import install_mathjax
In [2]: install_mathjax()

Optional Science Packages

If you also want to install numpy or scipy you should install first gfortran.$ brew install gfortranAnd then, just use pip to install the packages:

$ pip install numpy
$ pip install scipy

For Matplotlib you also have to install the library pkg-config (which in my case, it was already installed). Moreover, you might want to install ffmpeg, which allows to save movies using matplotlib.animation library.

$ brew install pkg-config
$ brew install ffmpeg
$ pip install matplotlib

Whohaaa!! that was a little bit of installation!?! Hope it also worked for you! 🙂

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