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/
I want to install Python 2.7 in two places at once on my Windows machine. For example, one in c:\python27 and another in c:\myproduct\python27. The official installer refuses to let me do this. If there is already an installation when I run the installer, it prompts me and asks if I want to Change, Repair or Remove the existing installation.
The TARGETDIR trick mentioned elsewhere on Stackoverflow doesn't work either - I get the same result if I type the following into a cmd window:
msiexec /i python-2.7.8.msi TARGETDIR=c:\myproduct\python27
So, is there anyway to install Python 2.7 twice on my Windows machine?
Reasons I want to do this are:
My product requires a 32-bit version of Python 2.7 to be installed because it uses ctypes to load a 32-bit DLL. If the user already has a 64-bit version of 2.7 installed, I don't think it is safe to install the 32-bit version over the top.
Relying on the users pre-installed Python 2.7 is bad because they might uninstall it later. That would stop my product from working.
It reduces the complexity of testing my product if I can make its installer always install a known version of Python. I can rely on it being in a known state.
I'd like to add the pyreadline module to the Python install that is part of my product. I suspect most users would rather that I did not mess around with their Python install.
When a user uninstalls my product, the Python it installed should also be removed. If I installed Python in the standard place the user might come to use it for other purposes and be surprised when it goes missing when they uninstall my product.
It appears that you should be able to install the 32 bit version of Python 2.7 in another folder when the 64-bit version is already installed. See How do I install Python 2.7.3 32 bit and 64 bit on Windows side by side for a description. However it may be tricky to automate this, you might have to get users to install it themselves.
I would suggest you ask your users to install Python 2.7 32-bit, and give them instructions on how to do it if they already have a conflicting 64-bit version. Then in your installation you:
Ensure that virtualenv is installed (and install it if it is not).
Create a virtualenv in your application folder.
That addresses everything except the second item on your list and I think you simply have to accept that no matter what you do, if someone removes a component that you need your application will fail. If they do that they can use the 'repair' option on your installer from which you can either reinstall the missing Python or tell them that's what they need to do.
To install virtualenv I would first install pip (see https://pip.pypa.io/en/latest/installing.html for instructions, you need to download get_pip.py and run it with the Python 2.7 interpreter), then just run pip install virtualenv.
Being fairly new to programming, I am having trouble understanding exactly what Homebrew does... or rather - why it is needed. I know it contains pip for package management, but so does Virtualenv and I'm planning on installing this in due course.
Does Homebrew install another version of python that is not the system version, upon which you would install Virtualenv and manage the different development environments from there?
I have a clean install of OSX Lion and I want to keep my projects separated, but am unsure why I need Homebrew.
I realise this is basic stuff, but if someone could explain it, I would be grateful.
Homebrew is just a package manager for Mac, like pip for Python. Of course you never need a package manager, you can just get all the programs, or libraries in case of pip and Pypi yourself. The point of package managers however is to ease this process and give you a simple interface to install the software, and also to remove it as that is usually not so simply when compiling things yourself etc.
That being said, Homebrew will only install things you tell it to install, so by just having Homebrew you don’t randomly get new versions of something. Homebrew is just a nice way to install general OSX stuff you need/want in general.
pip and virtualenv are python libraries and can be installed in any working python install including the one supplied by Apple as part of OSX and the python.org version.
Then it depends on what you need from python - if you just have to install python libraries or simple C linraries then you can just use easy_install and then pip, vittualenv other python tools.
If you are using more complex C libraries e.g. python interface for mysql then it helps to use a package manager like macports, homebrew or fink as the port writers will have sorted out the tricky dependencies. There are also other python installs from Enthought and Activestate that deal with some of the non simple cases e.g. scipy but are not general purpose package managers.
Macports and fink will install a separate version of python in /opt/local/bin or /sw/bin whilst I think homebrew will use Apple's python. *The difference is due to a difference of view of the package mangers design. Macports and fink were developed by people who experienced a lot of issues with different versions of software and so said that all our installs will be in a place only the package manager uses whilst Homebrew trys to use as much of the Apple supplied tools as possible so to add as little as needed.
I've installed Python 2.7 using macports and because of my $PATH variable, that's the one I get when I type $ python. However, virtualenv defaults to using Python 2.6 unless I remember to force it to do otherwise with the -p flag.
On a related note, globally running yolk -l shows the following:
Python - 2.6.1 - active development (/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/lib-dynload)
So my question is, should I do something to ensure the system is always using MacPorts' Python 2.7 or is it not worth worrying that Apple's Python 2.6.1 is apparently in the mix?
If you force python 2.7 globally on your system, things will break. You don't want to do that.
You should use virtualenvwrapper. It should choose your preferred python.
http://www.doughellmann.com/docs/virtualenvwrapper/install.html#python-interpreter-virtualenv-and-path
I have had similar problems, although not related specifically to virtualenv. I found that, after installing a particular version of python with macports, and having that version set as default, installing 3rd party modules that are build on or use python using macports solved all problems. You essentially end up with parallel builds, on top of different versions of python. I have a few, and switch between them using python_select. Also, see here on SO for how to get easy_install to work with your new python.
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.