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'm trying to follow the instructions here but no matter what I do it seems to be stuck on using Python 2.7.1 which is causing me errors currently.
http://docs.aws.amazon.com/elasticbeanstalk/latest/dg/eb-cli3-install-osx.html
Attached is an image showing my logs of upgrading to the newest awsebccli but its still stuck saying 2.7.1 when it should say 3.6 (or newer)
What could I be doing wrong?
I want to note that I also installed the newest version of python3 and python via brew.
Here is the exact error I'm getting if it helps also.
You do not want to upgrade the default python 2.7x installation or the python 3.x installation available on linux or OSX. There are usually lots of other libraries and applications that depend on this default installation. When you want to use a specific version of python the approach is to rely on a virtual enviorenment.
virtualenv is a tool to create isolated Python environments.
You are then leaving the system installation untouched. Getting the hang of virtualenv is quite easy. Once you create it (a one off task). All you need is to activate it and then you can use it as you would normally use the default python interpreter. How to copy packages from one virtualenv (or the system installation) to another is discussed here:
Installing python3 in a python2 virtual environment
I have installed on my MacBook Air (v10.10.5) a number of different Python Versions (2.7, 2.6 + 3). I have tried changing python PATH settings, however, it has become too awkward to maintain. Because of this, I wish to uninstall all versions (without damaging my OS) and then clean install Python 3. How can I do this?
First of, you cannot (and should not!) uninstall a version of python that is shipped with macOS. They are shipped for a reason and might break your system as soon as you remove them (as a lot of essential processes might rely on them).
Python2.7 for instance has been shipped with macOS for a long time. However, you are also able to download and install the same version of python (e.g. 2.7) yourself, which usually means you end up with conflicting versions and controlling your PATH becomes a fulltime job.
You are always safe to remove those versions that you installed yourself (but only those!).
How to do so depends greatly on how you installed them. If you've done so via downloaded packages of python.org look here for uninstall instructions. If you used another application like brew or macports you need to follow the guidelines of those programs which could be easily fetched via a Google search.
Good luck!
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.
I've been learning Python for a couple of weeks, and although I've been successfully develop apps for Google App Engine with Python 2.6.5, it specifically requires Python 2.5.
Being mindful of compatibility issues when uploading apps (it's a situation I'd rather avoid while learning Python), I wonder if it's possible to have 2.5 and 2.6.5 installed on the same machine. Ideally I'd like to use 2.6.5 as the default, and configure GAE to somehow use 2.5.
Absolutely.
If you're on *nix, you'd usually just use make altinstall instead of make install, that way the "python" binary won't get installed/overwritten, but instead you'd have e.g. python2.5 or python2.6 installed. Using a separate --prefix with the configure script is also an option, of course.
Some Linux distributions will have multiple versions available via their package managers. They'll similarly be installed as python2.5 etc. (With the distribution's blessed/native version also installed as the regular python binary.)
Windows users generally just install to different directories.
Yes, it is possible to install multiple versions of Python "side-by-side".
On Ubuntu, you simply install with
sudo apt-get install python2.5
(On the current version of Ubuntu, 10.04, python2.6 comes installed by default.)
To use python 2.6, just call python or /usr/bin/python.
To use python 2.5, you call /usr/bin/python2.5.
If you tell us your operating system, we may be able to provide more relevant details.
Another possibility is to use virtualenv.
OK, I figured out the answer to my own question, partly with the help of Nicholas Knight who pointed out that you just install different Python version to different Python directories. I was left scratching my head on how to get Google App Engine to use Python 2.5 (the required version) instead of Python 2.6. This is the answer:
1) Install Python 2.5.
2) Install Python 2.6 (or a more recent version), afterwards. This will be the system default.
3) Install the Google App Engine SDK.
4) Launch, "Google App Engine Launcher" from the Start Menu
5) Click Edit > Preferences, and enter the path to the pythonw.exe executable. Usually c:\Python25\pythonw.exe