I have two versions of Python installed in my computer, Python 3.4 and Python 2.7, and I use both of these installations. When I run a script, how do I choose which versions I want to use? May I rename the names of the executables for that (Python.exe -> Python27.exe)?
Thanks.
Both python 2.7 and python 3 coexist on one machine happily.
If you name the scripts .py for those you would like to run with python 2.3 and .py3 for those that you would like to run with python3 then you can just invoke the scripts by typing their names or by double clicking. These associations are set up by default by the installer.
You can force the python version on the command line, assuming both are on the path by typing python or python3 for any script file regardless of the extension.
It is also worth looking at virtualenv for your testing.
N.B. For installing from pypi you can use pip or pip3 and the install for the appropriate version will be done.
I am using a 32-bit and a 64-bit version of Python 2.7.6 on the same Windows machine, and the solution to that was to use Winpython for the 64-bit version, which is portable.
The downside is that doubleclicking in the file manager will attempt to run a Python script with the 32-bit version (which is a non-portable installation), but I'm mostly writing and running scripts inside Spyder, and there's one version of it with each Python installation. Both have independent Pythonpaths, and have never had any problems with each other. Winpython is aimed at scientific use, though, so it may not come with all the libraries you may need.
Related
I'm newbie of python programming.
I have windows 7 laptop and I'm also running virtual box Ubuntu.
I manually installed python3.5 on Win7 through Eclipse first. The default python version in my Virtualbox Ubuntu is 2.7.11.
Is it possible for me to install python packages through my VirtualBox to my Win7 python3.5?
Will it bring any problem with multiple versions of python.
python 3.5 packages do not work with python 2.7 and vice versa.
And I even think that you can't install packages from linux to windows.
I think what you wish to accomplish is to have a same version Python across both machine.
Best way is to go about doing it is to either install Python 2.7.x on Windows 7 or upgrade python 2.7.x on your Ubuntu to Python 3.5.x. Neither is good or bad.
To upgrade your Python 2.7.x to 3.x.x on your ubuntu machine,follow the instructions here.
If you wish to wish to install Python 2.7.x on your Windows,simply download the compatible exe from official page .It will create a folder under c: e.g. C:\Python27 .Thereafter,add the python path to environment variable PATH.
As for installing packages,the command remains the same across both OS.
pip install <package-name>
Usually packages have dedicated versions for different python versions.pip install will automatically resolve versions and install the compatible package version.
The Ubuntu VirtualBox is not just a linux-looking frontend to your existing Win7 install. It's a completely separate OS that runs as if it were on a separate computer. You can set up shared folders to share data between the host and guest, but trying to use Linux to install programs on Windows would be error-prone and risky even if you could do it.
If you plan to be using Python on Windows, you'll need to install the packages on Windows, and a Linux VirtualBox isn't going to help you with that at all. If you're uncomfortable with the Windows command line, read up on some tutorials. There are also some alternative Windows shells that provide some advantages over the built-in CMD.
If you'd rather work on Linux, you can do that, but you'd want to do it entirely inside the VirtualBox. Inside Linux, you could install the version of Python you want, install the packages you want, and use whatever dev tools you want, as if you were working on a Linux computer. (Although in this case I have to wonder why you aren't actually using a Linux computer instead of a Windows one.)
I am guessing that I am not the only one using non-system Python 2.7.2 for scientific computations on 6.2 PUIAS Linux (RedHat)). My Python 2.7.2 is installed in the sandbox and I call it with the command python2.7. When I need to execute scripts this is not the problem. However, I would like to use ipython instead default Python shell for interactive use. I added ipython using yum? When I start it, it defaults to system python. How do I force it to load python2.7?
Thanks a bunch!
IPython is a Python package. When you have multiple Pythons, you must (generally, barring PYTHONPATH hacks) install a package for a given Python. yum would only install it for the System Python, so you must install it separately for your own Python. The solution is to simply pip install ipython with your own Python (install distribute/pip first, if you haven't).
I am going to answer my own question. For people who are using Python for scientific computing on RedHat clones (PUIAS for example) the easiest way to get all they need is to use rpm package manager and Enthought Python Distribution (EPD for short). EPD installs everything in a sandbox so system tools which are based on an obsolete version of Python are not massed up. However, paths have to be adjusted for system or even easier on the user base so that the using shell invokes non-system tools.
Question: How to install Pyscripter on Cygwin?
Scenerio: I have installed portable apps on a usb, then installed cygwin portable version 0.9 on it. Under cygwin, I have installed Python 2.6. I am curerntly using it with the idle IDE but I would like to use Pyscripter instead.
I can not use portable python because I need to install additional modules on python such as pyevolve and Cantera. Alternatively, maybe someone could let me know how to add these modules to portable python.
You can create virtualenv in your usb. And just switch it on in any other computer via Cygwin from our usb. It is not a way to install Pyscripter. But it is way for add modules to your portable version of python.
For anyone else trying this, note that PyScripter is intended to run under Windows, not Linux. The steps are: (1) in Windows, install a python distribution from python.org, and (2) in Windows, install PyScripter.
Note, too, that PyScripter has the desired console (interactive python interpreter) window, and a pip-based package manager that allows adding packages. For example, to add Pandas to an app, do the following:
menu: Tools menu
submenu: Tools
menu item: Install packages with pip
Package Name: pandas
The correct pandas package with required dependencies will be installed. (At least, that is what happened in my case). I was then able to import pandas into my app and use it without any problem.
Cygwin is a Linux environment that installs/runs under Windows. One of its main claims to fame is that it allows you to use Linux commands at the Windows CMD prompt. It also allows you to install/run certain Linux apps, which you then run in the Cygwin (and/or Cygwin-X graphical) environment. For example, it is possible to install/run Eric6 (a graphical Linux python IDE) under Cygwin. (I tried that, it worked - but not as great as Pyscripter)
For my money, I found that Pyscripter under Windows works great - and is much, much nicer than Eric6 under Cygwin. I am a Notepad++ user for HTML/js/PHP and started out using Anaconda (Spyder) to code in Python. PyScripter is much closer to NPP than, for e.g., Spyder or IDLE or Eric6 - and is more like what I had hoped to find in the Python world - and it simply runs under Windows like any other Windows app.
References:
https://sourceforge.net/projects/pyscripter
https://github.com/pyscripter/pyscripter
I'm running Python 2.7 on Windows 7 64-bit, and when I run the installer for setuptools it tells me that Python 2.7 is not installed. The specific error message is:
`Python Version 2.7 required which was not found in the registry`
My installed version of Python is:
`Python 2.7 (r27:82525, Jul 4 2010, 07:43:08) [MSC v.1500 64 bit (AMD64)] on win32`
I'm looking at the setuptools site and it doesn't mention any installers for 64-bit Windows. Have I missed something or do I have to install this from source?
Problem: you have 64-bit Python, and a 32-bit installer. This will cause problems for extension modules.
The reasons why the installer doesn't finds Python is the transparent 32-bit emulation from Windows 7. 64-bit and 32-bit programs will write to different parts of the Windows registry.
64-bit: HKLM|HKCU\SOFTWARE\
32-bit: HKLM|HKCU\SOFTWARE\wow6432node\.
This means that the 64-bit Python installer writes to HKLM\SOFTWARE\Python, but the 32-bit setuptools installer looks at HKLM\SOFTWARE\wow6432node\Python (this is handled by windows automatically, programs don't notice). This is expected behavior and not a bug.
Usually, you have these choices:
the "clean" way: use 32-bit Python if you have to use 32-bit modules or extensions
the other "clean" way: only use 64-bit installers when using 64-bit Python (see below)
what the answer above suggests: copy HKLM\SOFTWARE\Python to HKLM\SOFTWARE\wow6432node\Python, but this will cause problems with binary distributions, as 64-bit Python can't load 32-bit compiled modules (do NOT do this!)
install pure Python modules with setuptools instead of the distutils installer (easy_install or pip)
For setuptools itself, for example, you can't use a 32-bit installer for 64-bit Python as it includes binary files. But there's a 64-bit installer at http://www.lfd.uci.edu/~gohlke/pythonlibs/ (has many installers for other modules too). Nowadays, many packages on PyPi have binary distributions, so you can install them via pip.
Apparently (having faced related 64- and 32-bit issues on OS X) there is a bug in the Windows installer. I stumbled across this workaround, which might help - basically, you create your own registry value HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Python\PythonCore\2.6\InstallPath and copy over the InstallPath value from HKEY_LOCAL_MACHINE\SOFTWARE\Python\PythonCore\2.6\InstallPath. See the answer below for more details.
If you do this, beware that setuptools may only install 32-bit libraries.
NOTE: the responses below offer more detail, so please read them too.
I made a registry (.reg) file that will automatically change the registry for you. It works if it's installed in "C:\Python27":
Download 32-bit version HKEY_LOCAL_MACHINE|HKEY_CURRENT_USER\SOFTWARE\wow6432node\
Download 64-bit version HKEY_LOCAL_MACHINE|HKEY_CURRENT_USER\SOFTWARE\
Yes, you are correct, the issue is with 64-bit Python and 32-bit installer for setuptools.
The best way to get 64-bit setuptools installed on Windows is to download ez_setup.py to C:\Python27\Scripts and run it. It will download appropriate 64-bit .egg file for setuptools and install it for you.
Source: http://pypi.python.org/pypi/setuptools
P.S. I'd recommend against using 3rd party 64-bit .exe setuptools installers or manipulating registry
Create a file named python2.7.reg (registry file) and put this content into it:
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Python\PythonCore\2.7]
[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Python\PythonCore\2.7\Help]
[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Python\PythonCore\2.7\Help\MainPythonDocumentation]
#="C:\\Python27\\Doc\\python26.chm"
[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Python\PythonCore\2.7\InstallPath]
#="C:\\Python27\\"
[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Python\PythonCore\2.7\InstallPath\InstallGroup]
#="Python 2.7"
[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Python\PythonCore\2.7\Modules]
[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Python\PythonCore\2.7\PythonPath]
#="C:\\Python27\\Lib;C:\\Python27\\DLLs;C:\\Python27\\Lib\\lib-tk"
And make sure every path is right!
Then run (merge) it and done :)
Get the file register.py from this gist. Save it on your C drive or D drive, go to CMD to run it with:
'python register.py'
Then you will be able to install it.
For 64-bit Python on Windows download ez_setup.py and run it; it will download the appropriate .egg file and install it for you.
At the time of writing the .exe installer does not support 64-bit versions of Python for Windows, due to a distutils installer compatibility issue.
To allow Windows installers to find the installed Python directory in Windows 7, OR, change which Python installation to install an installer into, add the installed path into the InstallPath registry key's (Default) value:
HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Python\PythonCore\2.X\InstallPath
Where "X" is the Python version (that is, 2.5, 2.6, or 2.7).
I tried the above and adding the registry keys to the LOCALMACHINE was not getting the job done. So in case you are still stuck , try this.
Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\SOFTWARE\Python]
[HKEY_CURRENT_USER\SOFTWARE\Python\PythonCore]
[HKEY_CURRENT_USER\SOFTWARE\Python\PythonCore\2.7]
[HKEY_CURRENT_USER\SOFTWARE\Python\PythonCore\2.7\Help]
[HKEY_CURRENT_USER\SOFTWARE\Python\PythonCore\2.7\Help\Main Python Documentation]
#="C:\Python27\Doc\python272.chm"
[HKEY_CURRENT_USER\SOFTWARE\Python\PythonCore\2.7\InstallPath]
#="C:\Python27\"
[HKEY_CURRENT_USER\SOFTWARE\Python\PythonCore\2.7\InstallPath\InstallGroup]
#="Python 2.7"
[HKEY_CURRENT_USER\SOFTWARE\Python\PythonCore\2.7\Modules]
[HKEY_CURRENT_USER\SOFTWARE\Python\PythonCore\2.7\PythonPath]
#="C:\Python27\Lib;C:\Python27\DLLs;C:\Python27\Lib\lib-tk"
Copy paste the above in notepad and save it as Python27.reg . Now run/merge the file as mentioned in the answers above. (Make sure the paths of Python installation are corrected as per your installation.
It simply does ,what the above answers suggest for a local machine ,to the current user.
Here is a link to another post/thread. I was able run this script to automate registration of Python 2.7. (Make sure to run it from the Python 2.x .exe you want to register!)
To register Python 3.x I had to modify the print syntax and import winreg (instead of _winreg), then run the Python 3 .exe.
https://stackoverflow.com/a/29633714/3568893
You can find 64bit installers for a lot of libs here: http://www.lfd.uci.edu/~gohlke/pythonlibs/
Various software installations on my laptop each require their own particular version of Python. ViewVC requires Python 2.5 and Blender requires Python 2.6. Mercurial (thankfully) comes with its Python interpreter packaged in a DLL in the Mercurial installation itself.
How do I get by without having to install the entire Python environment each time? Is there some minimal installer which will install the bare minimum without affecting other programs? Can I modify the Blender and ViewVC installations so that they too use their own Python-in-a-DLL?
It's hard to know which "bare minimum" the Blender scripts you'll want to use in the future may be counting on (short of the full Python standard library, which isn't all that large in term of disk space after all). Why not install both Python 2.5 and 2.6? They can coexist nicely (if your scriptable apps use hashbangs like #!/usr/bin/env python instead of specifically mentioning python2.5 or python2.6, you may need to trick out their PATHs just a little bit).
You should be able to get away with installing the Python binaries in the same tree as the specific application I believe (Totally untested hunch though).