Develop Reference

MacOs Monterey Python3 as default

I am currently trying to change my default Python version to Python3. This proves to be harder than expected.
I have already tried the following things:
I have tried to change the alias by doing alias python python3 but this seems to just change it for the running Terminal session
I have installed Python3 again with Homebrew and tried to change the directory within the zshellruncommand by defining it myself and editing it in vim
to be honest I don't really understand the process and just followed along with a tutorial but it didn't work.
I tried the command ln -s -f /opt/homebrew/bin/python3 /usr/bin/python to change the directories but it returned ln: /usr/bin/python: Operation not permitted
to deal with this problem I have already given the Terminal full access to the local harddrive but it is still not working properly
Hoping for some advise,
thanks in advance

First make sure the installed version is linked:
brew link python
then on your .bash_profile or .bashrc (.zshrc if you're using zsh) write this:
export PATH="/usr/local/opt/python#X.Y/libexec/bin:$PATH"
change X and Y to your python version

I think it's easier to just change your user shell environment instead of changing the system level environment.
vi ~/.bash
Then type
alias python=python3
Save your file by pressing Esc -> type :wq
Update your shell environment
source ~/.bash
Check your Python version.
python -V
Final result
Python 3.9.10
This works in my past few versions MacOS.

Python trouble after Mac update: "No such file or directory" [duplicate]

When I switch my PyCharm to use Python 3.4.3 and I am getting the error:
Invalid Python SDK
Also PyCharm does not automatically find the Python 3.4 interpreter for me, even though it is on the desired path /Library/Frameworks/Python.framework/Versions/3.4/bin/python3.4. See the screenshot:
Despite this the interpreter does work. I am able to get correct output as expected, but code completion related to Python 3.4 is not working.
E.g. print("hello world!) still shows an error on the editor, but the console shows the correct output.

This also happened to me. I renamed a repository and then my virtual environment got stuck in the old path.
I grepped all configuration files and could not find any reference to the old one.
What finally solved the problem was to clear caches with the option File > Invalidate Caches / Restart...:

I had the same issue.
Try to comment/remove the PYTHONPATH variable in your ~/.bash_profile
#export PYTHONPATH=/usr/local/lib/python2.7/site-packages/
If it does not help it also may be useful to look in the idea.log for the errors:
/Users/username/Library/Logs/PyCharm40/idea.log
I had the following errors:
Your PYTHONPATH points to a site-packages dir for Python 2.x but you are running Python 3.x!
PYTHONPATH is currently: "/usr/local/lib/python2.7/site-packages/"
You should `unset PYTHONPATH` to fix this.

I go the same error message in Windows version of PyCharm after I re-installed Python (3.5) on a different location. The problem was that most of my existing virtual environments registered in PyCharm were still referencing the old installation of Python.
I resolved it by deleting these existing virtual environments and creating a new one. If deleting existing interpreters (in virtual environment) is not an option, you should be able to modify them instead in File | Settings | Project Interpreter

I got the same issue, when I updated Python (3.x) version via Home brew in MacOS.
Above answers didn't work for me. But with those, I realize that, it's an issue with linking the directories. I deleted ~/.virtualenvs folder and recreated all virtual envs.
$ ls -a ~/.virtualenvs
local-dev wdias-dev
$ rm -rf ~/.virtualenvs
$ which python3
/usr/local/bin/python3
$ mkvirtualenv local-dev --python=/usr/local/bin/python3
$ mkvirtualenv wdias-dev --python=/usr/local/bin/python3
Open the PyCharm again, and it works fine.

I couldn't get anything to work, so I cloned my conda env (see how), called it something else, and then set it in PyCharm to the new one.

For me, changing the paths in ~\venv\pyvenv.cfg made PyCharm recognize the new environment after bringing my projects to a new PC.

I had the same issue in Windows10. I was so frustrated, beacause everything seems looked OK. I've added PYTHONPATH, I've restarted Pycharm and deleted old virtualenv folders and created new... It did't work.
And at the end I have just opened Pycharm in an administrator mode and it works!

When creating a new project my interpreter was set to python 2.7 so I had to change that to python3 and everything works like a charm

I got the same problem with Pop OS 21.04 and Pycharm installed via Flatpack. So i remove it and installed via Snap and started working again.

I ended up having to install Python as an admin and make sure it installed to the C:\Program Files\Python310 folder. I think The option was to make sure it installed for all users. If I installed it under for user's appdata it wouldn't work.
Once I did that I was able to point pycharm to the C:\Program Files\Python310\ for the interpreter. Pretty annoying but finally got it working

I've solved it too. Uninstalled python 3.10, installed python 3.9. Changed the python interpreter to 3.9 through pycharm setting. Created a new virtual environment.

How to get Conda and Virtualenv to work on mac OS Catalina?

I previously had Conda running smoothly on Mojave, but I've found that the upgrade to Catalina moves the "anaconda3" folder to your Desktop > Relocated Items > Security > anaconda3. It seems Catalina's security settings may not allow applications to install directly under the user directory anymore.
I tried the suggestion here, written below:
Hi, I might have a solution
Copy the folder anaconda3 located in Relocated Items to /Users/myname/
Open Terminal
Enter: export PATH=''/Users/myname/anaconda3/bin:$PATH"
Enter: conda init zsh
It worked! Good luck!
But this doesn't work for me. After conda init zsh I get:
-bash: /Users/USER/anaconda3/bin/conda: /anaconda3/bin/python: bad interpreter: No such file or directory
How can I get Conda up and running again without losing all my virtual environments? Thanks!
Update
I got Conda to work following #Ted Shaowang's suggestion. This means that conda env list shows all the virtual environments created via Conda.
However I am still experiencing an issue with virtualenv as since I changed the default anaconda3 file locations, python cannot be found.
The python executable located at .virtualenvs/env/bin/python cannot be found. Do I need to make further changes in order for python to work from virtualenv too?

I have the exact same problem and this works for me:
After you move anaconda from "Relocated Items" to ~/anaconda3, edit the first line of ~/anaconda3/bin/conda file from #!/anaconda3/bin/python to #!/Users/USERNAME/anaconda3/bin/python to reflect the change.

I would probably abstain from using the above solution. That ~/anaconda3/bin directory has lots of runnables (not just the conda one) that would need to be altered in this manual way. For example, unless you make the same change you cannot run jupyter notebook either, neither from base nor from other envs you might have.
My tip: Try getting a requirements file for your virtual envs, and do a fresh installation. You could use pipreqs to get the requirements used for individual projects: https://www.idiotinside.com/2015/05/10/python-auto-generate-requirements-txt/

No solution will be completely working without fixing the baked-in hard-coded prefix entries in files. There's a longer description and a recommended fix at https://www.anaconda.com/how-to-restore-anaconda-after-macos-catalina-update/

Technically this is reinstalling anaconda, however, I restored all my conda envs so, hopefully this is an acceptable solution!
Here is how I got it working on Catalina as of a few minutes ago (now using z-shell):
- Verified the existence of "Relocated Items" directory on my desktop and the "anaconda3" directory and its contents inside
- Navigated into the envs directory under "anaconda3" and left the finder window open (see screenshot)
THEN:
opened new Terminal (z-shell)
ran (this installed to /usr/local/anaconda3):
brew cask install anaconda
after installation was successful I opened my ~/.zshrc file (for my z-shell aliases) and added the following line:
export PATH="/usr/local/anaconda3/bin:$PATH"
saved my ~/.zshrc file, then reloaded with:
source ~/.zshrc
to verify conda command works now, I ran:
conda env list
for me, this showed a base env and that was it
then open Finder to the new envs location:
open /usr/local/anaconda3/envs/.
I dragged (moved) all my old envs into the new envs folder, and then ran:
conda env list
And all my old envs are back! :)
updated my PyCharm interpreter / env paths to reflect the new locations of these envs (had to restart PyCharm after, but now it works!)
DONE

Unsure whether this is considered a comment or at least a temporary answer, but I would refrain from attempting to fix any Catalina compatibility issues with Anaconda for now. See this GitHub issue.

I have the same problem, and this work for me :
My solution:
Copy your anaconda3 from Relocated Items folder
Paste in User/YourUserName
Open conda file in anaconda3/bin with the editor and edit the first line #!/anaconda3/bin/python to #!/Users/YourUserName/anaconda3/bin/python
Save it and run conda file
Open Terminal
Run this : export PATH=''/Users/YourUserName/anaconda3/bin:$PATH"
Run conda init zsh

I had incurred the same issue, and the following solution worked for me, and this is the easiest solution:
Instead of messing around copying the anaconda3 file from relocated items into User/USERNAME directory, better would be just to reinstall anaconda navigator's latest version from its official website : https://www.anaconda.com/distribution/#macos
While installation, it will ask you some permissions which are a result of new Apple Security Policies, just grant them, and it works just the way it should after this fresh installation!

This is what worked for me.
These are my header files (Catalina 10.15):
/Library/Developer/CommandLineTools/usr/include/c++/v1/stdio.h
/Library/Developer/CommandLineTools/SDKs/MacOSX10.14.sdk/usr/include/sys/stdio.h
/Library/Developer/CommandLineTools/SDKs/MacOSX10.14.sdk/usr/include/stdio.h
/Library/Developer/CommandLineTools/SDKs/MacOSX10.14.sdk/System/Library/Frameworks/Kernel.framework/Versions/A/Headers/sys/stdio.h
/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/stdio.h
/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/stdio.h
/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/System/Library/Frameworks/Kernel.framework/Versions/A/Headers/sys/stdio.h
Run sudo find /Library -name stdio.h to see where yours are located.
Mojave 10.14 header files:
$ sudo find /Library -name stdio.h
/Library/Developer/CommandLineTools/usr/include/c++/v1/stdio.h
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/stdio.h
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/stdio.h
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/System/Library/Frameworks/Kernel.framework/Versions/A/Headers/sys/stdio.h
As can be seen the SDKs are now split into MACOSX10.14 and 10.15 unlike in Mojave.
TLDR
So, these were my SDK folders on Catalina:
Rename MacOSX.sdk to MacOSX_orig.sdk
Right click on MacOSX10.14.sdk
Duplicate
Rename duplicate folder to MacOSX.sdk
Your folder structure should now look like this:
Like this we are basically using the previous version's OSX sdk as sysroot. Hope this helps.

Unable to run ipython notebook or anaconda (conda) commands in terminal

I am trying to get the ipynb running on my Mac, but I am running into some trouble. I specifically want to run the ipynb that comes with Anaconda.
This question is very close to helping me but I am not sure what to do with the results from checking which python, which python2.7, which ipython.
When I type 'ipython' into the terminal, I get
/bin/bash: /Users/me/anaconda/bin/python.app: No such file or directory
Anaconda isn't even located in /Users/me/ so I don't know why bash is looking there when I've put /usr/local/bin/anaconda/bin at the front of my path (which I did after that post suggested I check my path variable).
$ which anaconda
/usr/local/bin/anaconda/bin/anaconda
$ which python
/usr/local/bin/anaconda/bin/python`
$ which python2.7
/usr/local/bin/anaconda/bin/python2.7
$ which ipython
/usr/local/bin/anaconda/bin/ipython
I tried this to see if it worked, because I'm guessing it is related to the problem I am having:
$ conda -h
-bash: /usr/local/bin/anaconda/bin/conda: /Users/me/anaconda/bin/python: bad interpreter: No such file or directory`
From the responses I'm getting from bash, it looks like everything is pointing to where it should be, so then why, when I type ipython or conda into the terminal, do I get those errors?
(Not sure if this is related, but some posts I've seen refer to changing the pip file to point to the version of Python I want, but I am not quite sure where to find the 'pip file'. I went looking for it wherever my pip is stored but I couldn't find a file per say.)

It is most likely looking in the wrong place. Standard installations would be in /Users/username/anaconda/bin. If you have installed it in /usr/local/bin/anaconda/bin/python you will want to be sure it is in you .bash_profile. In terminal run the following:
open .bash_proflie
Add the following:
export PATH="/usr/local/bin/anaconda/bin:$PATH"
Again the usual Path would be:
export PATH="/Users/me/anaconda/bin:$PATH"
Be sure to relaunch terminal or run "source .bash_profile"

I solved this problem by moving anaconda to root ("/")

How to integrate Django and Cygwin?

I have a Windows box with cygwin, python and django installed.
Now I want to run django-admin, but when I do I get the error:
$ django-admin.py
c:\Python26\python.exe: can't open file '/usr/bin/django-admin.py': [Errno 2] No such file or directory

From here
For Windows users, who do not have symlinking functionality available, you can copy django-admin.py to a location on your existing path or edit the PATH settings (under Settings - Control Panel - System - Advanced - Environment...) to point to its installed location.
hope this helps

I just ran into the exact same problem. I've found that if you already have the windows version of python installed, it seems to get priority over the cygwin version. I solved the problem by editing /etc/profile and changed:
PATH=/usr/local/bin:/usr/bin:/bin:/usr/X11R6/bin:$PATH
...to:
PATH=/usr/local/bin:/usr/bin:/bin:/usr/X11R6/bin:
...which I think stops cygwin from adding the normal windows path. Once you've got that working, download django into some directory, move into that directory and type:
python setup.py install
I was having problems to begin with because I had omitted the 'python' bit at the start

As for the step on how to start your django in cygwin
first open your windows command prompt
then register the python environment by doing this:
Path %path%;C:\Python27;C:\Python27\Scripts
then now go to the installation folder of your cygwin
cd C:\cygwin
then run the cygwin.bat like this:
C:\cygwin>cygwin.bat <enter>
then cygwin will open, and type python to see if it now working
$ python
Voila we are done!

Sort of sounds like the windows version of Python is trying to run instead of the cygwin one. What happens if you type this:
$ python django-admin.py
Here I'm assuming
$ which python
Finds the cygwin version of python (which will be something like /usr/bin/python).
You may also try (temporarily) uninstalling the windows version of python and use only cygwin.

Help us help you. Is there a reason why you are running the windows python interpreter (c:\Python26\python.exe) as oppose to the cygwin python interpreter (/usr/bin/python.exe)? That could be your problem. So to troubleshoot that, you might consider removing the windows native interpreter or simply making sure the cygwin path is listed before the c:\Python26 path in the windows global PATH variable.

Add the location of your django/bin folder (or wherever else you keep django-admin.py) to your PYTHONPATH environment variable.

Like Brian mentioned you are running the Windows version of Python which won't work with the Cygwin installation.
A word of warning. When I first started using Django, I tried installing it in Cygwin and had a variety of problems and ended up switching to the regular Windows version of Python. Unfortunately, I didn't document all my issues, but I remember some of them had to do with the database libraries. Anyway, that was a few months ago when I knew less about Django than I do now. Maybe the problems I ran into have been solved and perhaps now that I know more I could get it to work, but running Django on Cygwin does seem to be the road less traveled. Good luck. :)

Just copy the django-admin.py to the current location you are working on for e.g
on Cygwin:
<root>/projects/
on your windows directory it will look like this:
C:\cygwin\home\<your computer name>\projects\
once you copy the file, you can create your project by typing this command:
$ python django-admin.py startproject mysite
and that's all - you have completed your first project using the Cygwin linux-like environment.

Add two lines to .bash_profile and .bashrc files (view their difference here). You can find them in C:\cygwin\home\[username]:
export PATH=$PATH:/cygdrive/c/python2.7
export PYTHONPATH=$PYTHONPATH:/cygdrive/c/python2.7/Lib/site-packages
Hope this helps