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Mac OS X comes with Python 2.7 out of the box.
You do not need to install or configure anything else to use Python 2. Theseinstructions document the installation of Python 3.
The version of Python that ships with OS X is great for learning, but it’s notgood for development. The version shipped with OS X may be out of date from theofficial current Python release,which is considered the stable production version.
Doing it Right¶
Let’s install a real version of Python.
Before installing Python, you’ll need to install GCC. GCC can be obtainedby downloading Xcode, the smallerCommand Line Tools (must have anApple account) or the even smaller OSX-GCC-Installerpackage.
Note
If you already have Xcode installed, do not install OSX-GCC-Installer.In combination, the software can cause issues that are difficult todiagnose.
Note
If you perform a fresh install of Xcode, you will also need to add thecommandline tools by running xcode-select--install
on the terminal.
While OS X comes with a large number of Unix utilities, those familiar withLinux systems will notice one key component missing: a package manager.Homebrew fills this void.
To install Homebrew, open Terminal
oryour favorite OS X terminal emulator and run
The script will explain what changes it will make and prompt you before theinstallation begins.Once you’ve installed Homebrew, insert the Homebrew directory at the topof your PATH
environment variable. You can do this by adding the followingline at the bottom of your ~/.profile
file
If you have OS X 10.12 (Sierra) or older use this line instead
Now, we can install Python 3:
This will take a minute or two.
Pip¶
Homebrew installs pip
pointing to the Homebrew’d Python 3 for you.
Working with Python 3¶
At this point, you have the system Python 2.7 available, potentially theHomebrew version of Python 2 installed, and the Homebrewversion of Python 3 as well.
will launch the Homebrew-installed Python 3 interpreter.
will launch the Homebrew-installed Python 2 interpreter (if any).
will launch the Homebrew-installed Python 3 interpreter.
If the Homebrew version of Python 2 is installed then pip2
will point to Python 2.If the Homebrew version of Python 3 is installed then pip
will point to Python 3.
The rest of the guide will assume that python
references Python 3.
Pipenv & Virtual Environments¶
The next step is to install Pipenv, so you can install dependencies and manage virtual environments.
A Virtual Environment is a tool to keep the dependencies required by different projectsin separate places, by creating virtual Python environments for them. It solves the“Project X depends on version 1.x but, Project Y needs 4.x” dilemma, and keepsyour global site-packages directory clean and manageable.
For example, you can work on a project which requires Django 1.10 while alsomaintaining a project which requires Django 1.8.
So, onward! To the Pipenv & Virtual Environments docs!
This page is a remixed version of another guide,which is available under the same license.
- Warnings
- Installation
- PATH and .bash_profile
- Homebrew - pyenv
- Uninstall python
- Homebrew
It’s easy to install multiple versions of python on a Mac computer using installers from python.org, Homebrew, Conda, or other sources. This could create conflicts if a user wants to run one version of python but bash calls a different version instead.
This is guide will show you how to:
- modify your bash profile to change which version of python is called by bash first.
- use virtual environments to specify a version of python that will run a project.
- uninstall specific versions of python.
Mac OS needs python
DO NOT remove any versions of Python found in the following folders:
/usr/bin
system/Library
These versions of Python—which should be Python 2.7—are installed by Apple and used by Mac OS and other software to perform some functions. Deleting Python from these directories will break Mac OS and force you to reinstall it on your computer.
Other projects may need specific versions of python
You may have a python project or you may use python packages that require particular versions of Python. Uninstalling those versions would prevent those projects or packages from working until that version of python is reinstalled. For example, Python 3 is a dependency of Numpy; if you uninstalled Python 3, then Numpy wouldn’t work until you reinstalled Python 3.
Three common methods of installing python can be found here:
python.org
The python.org (python.org) installer can be found here.
Homebrew
First install Homebrew. The instructions are here, or enter the following command:
To install Python 3:
To install Python 2:
Anaconda
Anaconda is generally used for scientific and machine learning applications.
For Ananconda follow installation instructions here.
Miniconda is a stripped down version of Anaconda.
For Miniconda follow installation instructions here.
PATH
The path is a list of directories that your shell will look through when you execute a command. You can display the path on your computer using the echo $PATH
command:
The directories above are separated by a colon, this is what they look like displayed in sequence:
- /Library/Frameworks/Python.framework/Versions/3.7/bin
- /Users/username/anaconda3/bin
- /Library/Frameworks/Python.framework/Versions/2.7/bin
- /Users/username/miniconda2/bin
- /Users/username/miniconda3/bin
- /Library/Frameworks/Python.framework/Versions/3.6/bin
- /usr/local/bin
- /usr/bin
- /bin
- /usr/sbin
- /sbin
- /usr/texbin
- /opt/X11/bin
- /usr/X11/bin
- /usr/local/git/bin
When you ask your shell to run a particular command or run an interpreter, python
for example, the shell looks through the different directories listed in the PATH in order they’re presented above. When the shell finds that command, it stops and calls it even if there is another version of the same command, with the same name, further down in the list.
.bash_profile
The bash profile is a set of instructions that are run by the shell when the user logs in to bash. You can add a variety of preferences to the bash profile, including modifications to the PATH. When anaconda, miniconda or other versions of python are installed they automatically add paths to their respective versions of python to the top of the bash profile.
Bash reads the bash profile in sequential order — from top to bottom — and adds those paths to the PATH in the order that they’re read. This means that the last path at the bottom of the bash profile will end up as the first path in the PATH. This means that if you have Python 3.6 installed on your computer, and then decide to add python 3.7, but keep 3.6, the installer will add Python 3.7 to the top of the bash profile but it will end up after python 3.6 in the PATH. Entering python3
in bash will call python 3.6, not 3.7.
Mac Python Environment
If that was confusing compare the order that the python paths are added to my bash profile below to the PATH listed above. You’ll notice that their respective orders are opposite from each other.
Enter the following command to open the bash profile in TextEdit:
My .bash_profile currently looks like this:
If you want to keep all of your installed versions of python, but want bash to open a different version first, just copy and paste it to the bottom of the bash profile. If you don’t want bash to run a particular version of python then delete it from bash profile and uninstall that version by following the instructions further down.
Don’t forget to save the bash profile before closing TextEdit. You also have to reload the bash profile in bash before any changes take effect. Just enter one of the following commands:
source ~/.bash_profile
. ~/.bash_profile
Pyenv is a Homebrew package that allows a user to install multiple versions of python in Homebrew and specify which version of python they’d like to run.
Install pyenv:
Install different versions of python:
Show which versions of python are installed:
The asterisk indicates that the system version of python is active, but 3.5.0 and 3.6.0 are also installed.
Pyenv Local
Create a folder called PythonLocalProject
, then display the version of python called by bash by entering python -V
:
Now enter:
This creates a .python-version
file which tells pyenv
which version of python to run in that directory.

Entering ls -la
shows us that file:
Now enter pyenv versions
:
And running this command shows which version of python is called by pyenv:
To change pyenv to the system version of version 3.6.0 enter:
This procedure is fine, you can set a version of python to run in a particular folder. But what if you want to use pyenv to set a global version of python.
Pyenv Global
Pyenv gives these instructions when you enter pyenv init
in bash:
Open the bash profile:
open ~/.bash_profile
Add this text to the bottom of the file:
eval '$(pyenv init -)'
Save the file and then enter:
source ~/.bash_profile
Entering echo $PATH
will show that a pyenv shim has been added to the beginnning of the path:
/Users/username/.pyenv/shims:
And which python
will return:
/Users/username/.pyenv/shims/python
This means that bash will run the version of python set by pyenv.
Navigate to a folder that doesn’t have a .python-version
file and enter:
This shows us that the global version of python is 3.6.0 and it is set by pyenv
.
So this shows that bash will run whichever version of python that is set in pyenv.
If you navigate back to the PythonLocalProject
folder with the .python-version
file and run python -V
you will notice that it doesn’t run the global version of python, it runs whichever version was last set with the pyenv local
command.
We can use the which
command to identify where specific versions of python are located:
This shows some overlap as some versions of python appear in both searches.
The locations of the anaconda and miniconda versions of python are self explanatory, so are the pyenv installs, the python.org installer places python in the /Library/Frameworks/Python.framework/
directory. Homebrew installs all packages, including python, in /usr/local/Cellar
, then Homebrew adds a symlink to /usr/local/bin
so that its version of python can be found in the path. Finally, Apple installs python in /usr/bin
. Remember, don’t delete that version.
Follow these instructions if you want to remove particular versions of python.
Python For Machine Learning Book
python.org
The python.org installer places all it’s installed files in the following folders:
- The system applications folder,
/Applications
/Library/Frameworks/Python.framework
/usr/local/bin
To delete all versions of python that were installed using the python.org installer, enter these commands in terminal:
To remove particular versions of python, you have to refer to the particular framework. The frameworks are installed in /Library/Frameworks/Python.framework
and particular versions are found in /Library/Frameworks/Python.framework/Versions/X.Y
. So for example if you wanted to uninstall only version 3.5 but leave other versions you would enter the following commands in bash:
Homebrew
To uninstall python that was installed using homebrew you need to identify what versions of python have been installed by Homebrew:
Enter:
Currently brew refers to python3 as python
and python 2 is called python@2
.
To uninstall both python2 and python3 enter the following:
Homebrew will refuse to uninstall python if it has dependencies, just uninstall python and ignore the dependencies:
Or, add the dependencies to the list of items to be uninstalled:
Troubleshooting
It’s possible to have Homebrew’s Python directory at the beginning of the $PATH but calling python
will still start the Apple installed version of Python or some other version. If that’s the case it’s possible that Homebrew’s Python install has become unlinked. This command will unlink and relink Python in Homebrew:
Uninstall Python from Pyenv
To list versions of python installed using pyenv enter:
To uninstall versions of python installed using pyenv enter:
Anaconda
The official removal instructions are found here, but deleting anaconda and miniconda is easy.
Anaconda and miniconda are installed in the users home directory: ~/miniconda2
, ~/miniconda3
,~/anaconda2
, or ~/anaconda3
Depending on which version or versions you have, just enter the following commands:
Python For Machine Learning And Data Science
Anaconda and miniconda also use several invisible files. Delete them by entering this command:
- Python Removal Instructions - towards the bottom of the README file.
And now for something completely different.