Installing python and all its stuff maybe a bit confusing if you’re installing it using Macports (MacPorts - The MacOS package manager). By default, Macports comes with many python ports, e.g., python24, python27, python34. Each of them is a separate version of python (2.4, 2.7, 3.4,…). It provides the users the ability to install and maintain multiple version of python at the same time.

To browse all versions of python provided by Macports, use this command

$ port search python
python26 @2.6.9 (lang)
    An interpreted, object-oriented programming language
python27 @2.7.6 (lang)
    An interpreted, object-oriented programming language

To install a specific version of python

$ port install python24 python27

When you install python through Macports, it will auto install the python_select port. This is a tool for switching among python versions. To view all the the installed python versions, execute this one

$ port select --list python
Available versions for python:
	none
	python24
	python25-apple
	python26-apple
	python27 (active)
	python27-apple

To set one version as the default one, use port select again

$ port select --set python python27
Selecting 'python27' for 'python' succeeded. 'python27' is now active.

Similarly, before installing pip, search for all available versions of pip

$ port search pip
py25-pip @1.3.1_1 (python, www)
    A tool for installing and managing Python packages.

py26-pip @1.5.4 (python, www)
    A tool for installing and managing Python packages.

py27-pip @1.5.4 (python, www)
    A tool for installing and managing Python packages.

Select the version of pip corresponding to the version of python that you are using and then install it

$ port install py27-pip

Again, you need to use port select to set the version of pip to use. Select the version corresponding to your running python version

$ port select --list pip
Available versions for pip:
	none
	pip24
	pip27 (active)
$ port select --set pip pip27
Selecting 'pip27' for 'pip' succeeded. 'pip27' is now active.

Now, python and pip have been installed successfully. Make sure that the Macports bin is in your PATH and stands before the default Mac OS one. When run the command which, it should be something similar to this

$ which python
/opt/local/Library/Frameworks/Python.framework/Versions/2.7/bin/python
$ which pip
/opt/local/Library/Frameworks/Python.framework/Versions/2.7/bin/pip

Now the best way to install virtualenv is to using pip

$ pip install virtualenv