Currently, I feel like my Python ecosystem is out of whack. Several years ago, I had shared my computer with someone else, and now I am discovering that my machine has many versions of Python scattered about. From what I could find, starting from Macintosh HD:
anaconda
Applications/Python 3.6
Contains IDLE, Python Launcher, etc...
Library/Python/2.7/site-packages
This contains things like pip and wheel (I am unsure what this is)
Library/Frameworks/Python.framework/Versions
This contains two folders, 3.5 and 3.6.
System/Library/Frameworks/Python.framework/Versions
Inside here there are many alias folders, all which point to 2.7
Is all of this supposed to be normal? I am trying to run Python from the terminal, yet I have been getting messages such as ImportError: No module named site. pip has also not been working.
Is there a way for me to reset the Python on my machine to just that which comes with macOS? I feel like starting over from a blank slate would be helpful, since I want to get things setup in some type of comprehendible way (e.g. a way in which I've set things up so I know what is on my machine instead of many random things put on it by another).
This is very normal. you have a preinstalled python2.7 which comes with macOS and another one "Anaconda" which has installed manually. You first need to check what is your default python path (version) on your macOS, I mean if you are using anaconda or the default pre-installed python2.x. To remind you can check like below:
python --version
output (for me): Python 3.7.6
then if you want to change it to another version/or use another version under conda you can check these two answeres of mine.
How to add anaconda to PATH?
and here:
How to set the default python3 to python3.7?
It is normal that when you install a package for your default python version you don't expect it to be installed on the other one too. Normally it is better to install python2.x as an environment of conda and switch between two environments with "conda activate py2" and "conda deactivate" to go back to your default version. for each of them, you need to be in the environment and then use pip.
if pip is not working, it may need to be installed. On macOS, as you remember, you can use
brew update
brew install pip
or "easy-install" instead of brew (or whatever you use for installation).
I am starting to learn Python on my Mac and use VS Code. At the bottom left corner I can select the Python version. Apparently I have four versions installed.
I know that macOS already has one installed (I am assuming it is the one in /System/Library/..). I must have (accidentally) installed the other versions.
What is the safe/recommended way to set up Python3 on Mac for development (I only want/need one version 3.xx)?
Where should I install pip3?
I don't want to mess around with the system's python version, but delete everything unnecessary.
Thank you for advice!
Do not delete python2.7 as it may be used by system. Other than that, whenever you want to create any project in python is recommended to create a virtual environment, this way you can always separate what version will every project use and what libraries will you install for a specific library. More infor https://docs.python.org/3/tutorial/venv.html and how to uninstall python from mac https://osxuninstaller.com/uninstall-guides/properly-uninstall-python-mac/
Could there possibly be hidden files that I would need to find. Or do I have to re-install Python 2.7 if I want to work with it?
Thanks
Python installations on OS X generally go in separately and don't uninstall each other. Also, the convention is still for the executable python to refer to 2 and python3 to refer to 3, so they don't even really overlap.
Common locations you might have python include
/usr/bin/python (the system installed one, probably an osx specific 2.7.5)
/Library/Frameworks/Python.framework/Versions/... This is where the ones you install from Python.org go, separately for each version.
Your homebrew directory if you are using that
Which one runs when you type python (or python3) depends on your PATH environment variable.
python --version - will give you the version of the currently used python in environment variable PATH.
Nothing gets uninstalled. You have to just adjust the PATH variable according what you will be using.
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:
Will having two different versions of python/Tk on the same machine cause problems?
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?
When I install third-party packages like numpy using a .dmg file, how do I control which version of python numpy installs into?
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.
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:
Install ActivePython 2.7
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:
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:$PATH to your ~/.profile will always give you direct access to the scripts installed for the selected python.
to avoid bad surprises, I've added a echo Selected python is \"$(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.
My windows laptop is being replaced due to some hardware problems. I've spent the last two years installing third party libraries every so often, which I'll need to reinstall on the new machine. I just need to:
Generate a list of third party python libs current installed
Reinstall those on the new machine
My thought right now is to look at c:\python\lib\site-packages and manually write out the list, then try to create a configuration file for Setuptools and EasyInstall which I could run as a script of sorts, which would install all these libraries. Is that feasible?
Take a look at pip's freeze command and install from requirements file:
http://pip.openplans.org/#freezing-requirements
Warning: pip may not be able to install all your packages in Windows (I think it has some limitations for some packages with native libraries that must be recompiled).
You might want to look into virtualenv. It lets you have a "virtual environment" for Python that would eliminate this need in the future. As for getting the old libs on the new system, you can check the PYTHONPATH environment variable and/or sys.path from the interpreter to see what all paths are searched and you can do some looking around to see what you'd need to install to get back to where you were.