I mistakenly deleted the old python installion on my system, i then downloaded the new python 3 release however when i type python into the terminal it still looks for it in the 2.7 directory. I looked through a few questions that said something about updating the path variable however ive had no luck, as to me it seems that python is only 4 files installed in the applications folder. I really would appreciate some help. Thank you
It is better if you reinstall your system from recovery mode. A lot of OSX software can rely on system python, even if it is not python projects. Then recomended way is use homebrew. You can have different python (2.7, 3.3, pypy) versions the same time.
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I've deinstalled and reinstalled a bunch of Python Versions and edited my system variables in order to clean up the quagmire of pip not being able to install packages to the right locations. Long story short: Sublime now can't find numpy (or any 3rd party module), because it somehow figured that the python 2.3 version that comes with ChemDraw is the one I really want to use, not the 3.9 version I had used previously.
I've tried a bunch of tutorials online (such as resetting everything to factory settings) however nothing seems to unlink the python build system from that python 2.3 version that came with ChemDraw. Even deinstalling everything and installing Sublime 4 keeps that association. Like...how?
So here's my problem: My build system for python is linked to the wrong python version and I don't know how to link it to the python 3.9 that's located in AppData/Programs.
How can I associate the python.exe of python 3.9 in AppData with my python Build System instead of the current python 2.3, which is located ProgramFiles?
Ok, so the problem was that there was a system variable called PYTHONPATH, which I don't remember setting. It seems that Chemdraw, if installed with ChemScript, installs it's own python installation, which is 2.X.
That python install seems to set its own system variable called PYTHONPATH, which Sublime seems to prioritize for it's default python build system.
Delete whatever incorrect path is set in PYTHONPATH and paste the following into it instead:
C:...\Python\Python39\Scripts;C:...\Python\Python39;C:...\Python\Launcher;
I admit at the beginning that I am a novice python developer, so I apologize in advance for questions that may seem stupid.
I prepared python script with GUI (Tkinter), which use plenty external libraries. I'm working on Windows. Currently, I share my program in the form of an .exe file for Windows users, who do not have Python installed on their PCs. Everything works.
Recently I received a query if I can compile my code on an executable file that is usable for Mac users.
I have a number of questions related to this:
1) can I do it from a PC with Windows or i need Mac? I guess I have to have access to a Mac.
2) will my code work on mac without any editing? What about external libraries? Do you know any easy way to copy/paste my "python with used libraries" from Windows to Mac?
3) will I create a executable file in the same way as Windows, I mean I will use a "Pyinstaller" type library?
Thank you in advance for your help.
1) can I do it from a PC with Windows or i need Mac? I guess I have to have access to a Mac.
You can use a virtual machine and build for mac.
2) will my code work on mac without any editing? What about external libraries? Do you know any easy way to copy/paste my "python with used libraries" from Windows to Mac?
Some libraries have different behavior between macOS and Windows, yes. You should consult the documentation for the libraries you are using.
3) will I create a executable file in the same way as Windows, I mean I will use a "Pyinstaller" type library?
If you're actually using pyinstaller then it is compatible with both mac and windows. You have to check that the library you're using is compatible with both by looking at their docs.
An example of this is to use virtualbox mac image.
Install virtualbox (see this)
Install MacOS (see this)
Install the correct python (obviously python.org)
git clone your repository
Setup your virtual environment (or just pip install -r requirements.txt with your requirements file but I'm a stickler about venvs)
Note: I know you said pyinstaller-like but pyinstaller has a note about macos.
Build!
You shouldn't have any trouble. Just make sure the version of python is the same, as I believe the default on mac is 2.7.
Also, python scripts aren't compiled, rather interpreted, so making the file executable doesn't really mean it's a binary file in this case. I'm not sure what method you used to run python on a computer that doesn't have python on it, as there are a few, but if you can manage to do that on windows, it should work on mac.
I've read through several questions and pages on the how and why of this, but after taking a look on my mac yesterday I found that I currently have 6 versions of python on my machine.
Three are located in /Library/Frameworks/Python.framework/Versions (2.5, 3.1, 3.2), and then I have three more in /System/Library/Frameworks/Python.framework/Versions (2.5, 2.6, and another).
Terminal seems to use MacPython 2.5 from the first path. I found that it is recommended that I let my Mac itself use MacPython and that I don't try to change that. I managed to add a 3.2 reference from the first path to $PATH, but Terminal doesn't really seem to pick up on that.
For Python development I have used IDLE in the past, but it doesn't have any syntax highlighting, and so I moved over to TextMate.
I have several questions:
- Why are there so many versions and are they all being used?
- How can I get all programs to use the same version?
- Why do some versions have IDLE and some don't, and more importantly why do the ones that don't, have all the 'Extras' installed, like PyOBjC?
How to know which Python is the used:
In the Terminal, type which python. It will show you the path to the active Python.
Why so many versions:
Probably leftovers of previous system upgrades: Tiger -> Leopard -> Snow Leopard, maybe.
How to point everything to the Python you want:
In your .profile or .bashrc add the line:
alias python='/path/to/the/python/of/your/choice'
I'd recommend to install Python via MacPorts. It's well maintained and comes with a CLI "chooser" allowing you to, well… choose the active Python.
I'm a newbie programmer just installing Python 3.2, but I know I also have an older version of Python on my machine. in fact, I think Macbook comes with it installed. Do I have to worry about having different versions on my computer when I try to start learning Python?
For the most part, you don't have to worry about conflicts with system Python. In fact it is recommended to install a different Python version instead of working with system Python. Also consider using virtualenv and virtualenvwrapper to maintain any dependencies for each project easily without conflicts.
It really depends what OS you're talking about. I'm assuming you're talking about a Mac, since you mentioned Macbook.
Macs come with 2.5 and 2.6 installed as far as I'm aware. At least mine has both those versions, and I've only installed 2.7 manually.
You can check which version of python is the current 'system' python by doing the following in terminal:
// check the version of system python
python --version
// tells you where the system version of python is on your PATH
which python
On *nix type Operating Systems, like your Mac, applications aren't really 'installed', like they are in Windows (eliding details). Instead, application files are placed in various different parts of the file system. Python, for example, is placed into the following directory (by default) when installing 2.7:
/Library/Frameworks/Python.framework/Versions/2.7/bin/python
Since this directory isn't on the system PATH, this version of python won't be used when simply calling python from the command line. The system will search all the folders in the PATH environment variable for an executable file called python. It will usually find it in /usr/bin/ or something similar.
To make a new version of Python the 'system' python, you have a couple of options:
Modify your .bash_profile, and prepend the path to your new python to the PATH environment variable.
symlink the new version of python to a directory already on your PATH like /usr/bin/
Be aware that Mac python installers can modify your .bash_profile (in your home directory), to force the new version to be the default system version. This is what my bash_profile shows:
# Setting PATH for Python 2.7
# The orginal version is saved in .bash_profile.pysave
PATH="/Library/Frameworks/Python.framework/Versions/2.7/bin:${PATH}"
export PATH
You can happily run multiple versions of python on the same system. A particular version is usually the default though, and that's whatever executable python file is found on the PATH first.
If you want to use a different version at any particular point in time, you can:
/path/to/python/2.4/python some_script.py
/path/to/python/2.7/python some_script.py
/path/to/python/3.2/python some_script.py
That will execute the script some_script.py under 3 different versions of python. Of course, you need to make sure that the /path/to/python is correct.
So yes, you need to be mindful about what version of python you are going to be using, hopefully this will guide you into understanding how applications are installed and which version of an application is launched by default when you don't provide a path.
Yes, 3.x Python syntax is not backward-compatible with 2.x. So if you learn Python 3.x you might not be able to port your knowledge to Python 2.x.
Moreover you should choose if you want to learn 3.x or 2.x. 2.x is far more widespread than 3.x, but 3.x is where Python is heading. No more innovation will happen in 2.x, and in mid-term most frameworks will be ported to 3.x (right now there are some notable exceptions)
Hope that helps!
In general, you should be fine. Since the Mac is BSD-based, it should maintain the "python" command as pointing to the version that your system requires, which is usually an older version like 2.5. You may have to use a command like python3 to run your Python 3 programs, but other than that it should be transparent to you.
As you learn and become more advanced, you can begin using the virtualenv system to maintain separate Python installations for multiple projects.
Python version with different major or minor version numbers can be installed in parallel. For example, you can have 2.4, 2.5, 2.6, 2.7 and 3.1 on the same machine. However, you can't have versions with the same major and minor number installed at the same time (at least, not without tricks), so you can't have 2.5.2 and 2.5.4 at the same time.
Note that you will have to install any third-party libraries once for every Python version.
It is very well possible to have multiple versions of python on your machine. Just make sure, that if you call python in your console it uses the python you want it to use. Same goes for your IDE.
Regarding the version: It is always nice to have the latest version on board (in python however there are compatibility issues to take into account) , since there might be features you want to use, that are only available with a certain version and upwards. Since this is sometimes tricky to find out, especially if you are new to the field, going with the latest version might be how you should proceed.
Be careful before installing new version of python.
Python has no backward compatibility.
Scripts written for python 2.7.* won't work on python 3
For example,
print "Hello" will work on python 2.7 but not on version3
How would I do this? The reason being I wanted to try some pygame out, but I have python 3 installed currently and have been learning with that. I'm also interested in trying out wxpython or something like that, but I haven't looked at their compatibilities yet.
EDIT:: im on a windows vista 64-bit
If you are on Windows, then just install another version of Python using the installer. It would be installed into another directory.
Then if you install other packages using the installer, it would ask you for which python installation to apply. If you use installation from source or easy_install, then just make sure that when you install, you are using the one of the proper version.
If you have many packages installed in your current python-3, then just make a zip backup of your current installation just in case.
Erm... yes. I just installed Python 3.0 on this computer to test it. You haven't specified your operating system, but I'm running Ubuntu 9.04 and I can explicitly specify the version of Python I want to run by typing python2.5 myscript.py or python3.0 myscript.py, depending on my needs.
Typically python is installed with a name like python2.6, so you can have more than one. There may be a symlink from python to one of the numbered files. Quite workable.
Yes, it is possible.
I maintain 3 python installations (2.5, 2.6, 3.0). The only issue that could be confusing is figuring out which Python version takes precedence in PATH variable (if any) . To execute a script for a specific version, you would go into the python directory for that version
C:\Python25\ , C:\Python26\, C:\Python30\, etc.
Drop the file in there, and run "python.exe file.py" from command-line.
You could even rename each python.exe to python25.exe python26.exe python30.exe and have each directory in PATH so it would be easy to execute any script on any version.
I would assume it'd be the same as running two versions of 2.x; as long as they're each in their own directory you should be OK.
You certainly can. On Mac Ports, there's a tool called python_select that lets you switch among python versions; if nothing like it exists on Windows (momentary googling didn't reveal one), it could certainly be written.
You can set up virtual python environments using virtualenv.