I am using tox to test my python packages. Now that python 2.7.13 has a release candidate, how do I test against this version using tox without immediately replacing my current python 2.7 version for normal use?
I know how to specify a path for python when creating a virtualenv and then I can install and run py.test. Tox builds its own virtualenv and I don't know how to influence the python version installed beyond selecting py27, py26, py35.
How can I solve this?
You can influence this using the PATH, by extending your PATH before calling tox (at least on Linux, probably not on Windows).
To get some more fine grained control and to get that to work on Windows (where AFAIK you cannot set an environment variable for a single command usage like on Unix/Linux), you can use the tox extension package tox-globinterpreter (disclaimer I am the author of that package) which you can install with pip.
The package adds a --scan option to tox which writes out an explicit mapping from py27, py36, etc to a python executable.
E.g. I do:
tox --scan /opt/python/{2,3}.?/bin/python /opt/python/pypy2/bin/pypy
on my Linux based system, where /opt/python/X.Y is a link to the latest released Python version as installed in /opt/python/X.Y.Z (or the latest version in case of development version like 3.6), this gives as output:
interpreters:
python2.6 /opt/python/2.6/bin/python
python2.7 /opt/python/2.7/bin/python
python3.2 /opt/python/3.2/bin/python
python3.3 /opt/python/3.3/bin/python
python3.4 /opt/python/3.4/bin/python
python3.5 /opt/python/3.5/bin/python
python3.6 /opt/python/3.6/bin/python
pypy /opt/python/pypy2/bin/pypy
When I change the scan to:
tox --scan /opt/python/2.6/bin/python /opt/python/2.7.13*/bin/python \
/opt/python/3.?/bin/python /opt/python/pypy2/bin/pypy
I get:
interpreters:
python2.6 /opt/python/2.6/bin/python
python2.7 /opt/python/2.7.13rc1/bin/python
python3.2 /opt/python/3.2/bin/python
python3.3 /opt/python/3.3/bin/python
python3.4 /opt/python/3.4/bin/python
python3.5 /opt/python/3.5/bin/python
python3.6 /opt/python/3.6/bin/python
pypy /opt/python/pypy2/bin/pypy
And tox -e py27 will be using the 2.7.13 release candidate. You can save the configuration file (in ~/.config/tox or %APPDATA%\tox) if switching back and forth, but rerunning the scan is pretty fast, so I would make a shell script/alias/batch file for that.
When I tried to run this command:
c:\python27\scripts\pip install nltk-3.2.1-py2.py3-none-any
I am getting the error:
no matching distribution found
Although i have installed nltk from
http://www.lfd.uci.edu/~gohlke/pythonlibs/#nltk
Kindly help.
I am working on Windows 8 64-bit Version
Installing new modules can be a nightmare if you are new to Python.First delete any old versions of NLTK if already installed. Open cmd navigate to C:\Users\user\AppData\Local\Programs\Python\Python35-32\Scripts, the default directory, using the command cd path_name_comes_here. Otherwise goto the path where you have installed python and goto the Scripts subfolder and use this path here onwards. Now the most preferred way is to use pip install module_you_want_to_install for anything in python. Pip automatically fetches everything it needs to install said module.
Simply use pip install nltk.
Another method is to use easy_install requirement_or_URL.
Some rare occasions its best to download the wheel from http://www.lfd.uci.edu/~gohlke/pythonlibs and from there you can simply use pip install downloaded_wheel_name again. But make sure to copy the name of the wheel EXACTLY.
Post installation make sure that your package is accessible from C:\Users\user\AppData\Local\Programs\Python\Python35-32\Lib\site-packages or a similar path depending on where you installed python.
Try Anaconda - Instead . Always works
C:\Users\sanan>conda install -c anaconda nltk
Fetching package metadata .............
Solving package specifications: .
Package plan for installation in environment C:\Users\sanan\Miniconda3:
The following NEW packages will be INSTALLED:
nltk: 3.2.4-py36_0 anaconda
The following packages will be UPDATED:
conda: 4.3.23-py36_0 --> 4.3.25-py36_0 anaconda
The following packages will be SUPERSEDED by a higher-priority channel:
conda-env: 2.6.0-0 --> 2.6.0-0 anaconda
Proceed ([y]/n)? y
conda-env-2.6. 100% |###############################| Time: 0:00:00 22.84 kB/s
nltk-3.2.4-py3 100% |###############################| Time: 0:00:02 774.24 kB/s
conda-4.3.25-p 100% |###############################| Time: 0:00:00 578.90 kB/s
After installation is complete .
import nltk
print(nltk.__version__)
C:\Public\Code\textnorm>python attempt1.py
3.2.4
I am running an old RHEL5 server and would like to install a beta version of the python module openrem from pip.
I create a virtual env in my folder and issue the command
pip install openrem==0.7.0b13
The setup.py for openrem 0.7.0b13 has the following requirements
requires = [
'django>=1.8,<1.9',
'django-filter >= 0.10',
'pytz >= 0a',
'humanize',
'pydicom >= 0.9.9',
'django-pagination',
'xlsxwriter',
'celery >= 3.1',
'argparse >= 1.2.1',
'django-qsstats-magic',
'python-dateutil',
'django-solo',
'django-crispy-forms'
]
However, I get the following message during the installation
Downloading/unpacking django>=1.8,<1.9 (from openrem==0.7.0b13)
Downloading Django-1.9rc1.tar.gz (7.3MB): 7.3MB downloaded
Running setup.py egg_info for package django
Low and behold django 1.9 is installed. The problem being openrem is incompatible with django 1.9. Why is pip ignoring the requirement to install django <1.9
All I've managed to dig up is this:
To mitigate this risk, do not use the foo >=0.3, <0.4 style
declaration, which has a purely numeric upper bound. <0.4 still admits
versions 0.4a0, 0.4a1, 0.4b0, 0.4c3, etc. Instead, use an upper bound
like <0.4a0, as in foo >=0.3, <0.4a0, when you write your
install_requires.
from: How to specify version ranges in install_requires (setuptools, distribute)
Perhaps you need to be more specific. You probably end up with django v 1.9.5 right? Seems a bit stupid, but there's probably some reason for it!
I'm running Windows and the shell/OS automatically runs Python based on the registry settings when you run a program on the command line. Will this break if I install a 2.x and 3.x version of Python on the same machine?
I want to play with Python 3 while still being able to run 2.x scripts on the same machine.
The official solution for coexistence seems to be the Python Launcher for Windows, PEP 397 which was included in Python 3.3.0. Installing the release dumps py.exe and pyw.exe launchers into %SYSTEMROOT% (C:\Windows) which is then associated with py and pyw scripts, respectively.
In order to use the new launcher (without manually setting up your own associations to it), leave the "Register Extensions" option enabled. I'm not quite sure why, but on my machine it left Py 2.7 as the "default" (of the launcher).
Running scripts by calling them directly from the command line will route them through the launcher and parse the shebang (if it exists). You can also explicitly call the launcher and use switches: py -3 mypy2script.py.
All manner of shebangs seem to work
#!C:\Python33\python.exe
#!python3
#!/usr/bin/env python3
as well as wanton abuses
#! notepad.exe
Here's my setup:
Install both Python 2.7 and 3.4 with the windows installers.
Go to C:\Python34 (the default install path) and change python.exe to python3.exe
Edit your environment variables to include C:\Python27\;C:\Python27\Scripts\;C:\Python34\;C:\Python34\Scripts\;
Now in command line you can use python for 2.7 and python3 for 3.4.
From version 3.3 Python introduced Launcher for Windows utility https://docs.python.org/3/using/windows.html#python-launcher-for-windows.
So to be able to use multiple versions of Python:
install Python 2.x (x is any version you need)
install Python 3.x (x is any version you need also you have to have one version 3.x >= 3.3)
open Command Prompt
type py -2.x to launch Python 2.x
type py -3.x to launch Python 3.x
You can have both installed.
You should write this in front of your script:
#!/bin/env python2.7
or, eventually...
#!/bin/env python3.6
Update
My solution works perfectly with Unix, after a quick search on Google, here is the Windows solution:
#!c:/Python/python3_6.exe -u
Same thing: in front of your script.
Here is a neat and clean way to install Python2 & Python3 on windows.
https://datascience.com.co/how-to-install-python-2-7-and-3-6-in-windows-10-add-python-path-281e7eae62a
My case: I had to install Apache cassandra. I already had Python3 installed in my D: drive. With loads of development work under process i didn't wanted to mess my Python3 installation. And, i needed Python2 only for Apache cassandra.
So i took following steps:
Downloaded & Installed Python2.
Added Python2 entries to classpath (C:\Python27;C:\Python27\Scripts)
Modified python.exe to python2.exe (as shown in image below)
Now i am able to run both. For Python 2(python2 --version) & Python 3 (python --version).
So, my Python3 installation remained intact.
I'm using 2.5, 2.6, and 3.0 from the shell with one line batch scripts of the form:
:: The # symbol at the start turns off the prompt from displaying the command.
:: The % represents an argument, while the * means all of them.
#c:\programs\pythonX.Y\python.exe %*
Name them pythonX.Y.bat and put them somewhere in your PATH. Copy the file for the preferred minor version (i.e. the latest) to pythonX.bat. (E.g. copy python2.6.bat python2.bat.) Then you can use python2 file.py from anywhere.
However, this doesn't help or even affect the Windows file association situation. For that you'll need a launcher program that reads the #! line, and then associate that with .py and .pyw files.
When you add both to environment variables there will a be a conflict because the two executable have the same name: python.exe.
Just rename one of them. In my case I renamed it to python3.exe.
So when I run python it will execute python.exe which is 2.7
and when I run python3 it will execute python3.exe which is 3.6
Here you go...
winpylaunch.py
#
# Looks for a directive in the form: #! C:\Python30\python.exe
# The directive must start with #! and contain ".exe".
# This will be assumed to be the correct python interpreter to
# use to run the script ON WINDOWS. If no interpreter is
# found then the script will be run with 'python.exe'.
# ie: whatever one is found on the path.
# For example, in a script which is saved as utf-8 and which
# runs on Linux and Windows and uses the Python 2.6 interpreter...
#
# #!/usr/bin/python
# #!C:\Python26\python.exe
# # -*- coding: utf-8 -*-
#
# When run on Linux, Linux uses the /usr/bin/python. When run
# on Windows using winpylaunch.py it uses C:\Python26\python.exe.
#
# To set up the association add this to the registry...
#
# HKEY_CLASSES_ROOT\Python.File\shell\open\command
# (Default) REG_SZ = "C:\Python30\python.exe" S:\usr\bin\winpylaunch.py "%1" %*
#
# NOTE: winpylaunch.py itself works with either 2.6 and 3.0. Once
# this entry has been added python files can be run on the
# commandline and the use of winpylaunch.py will be transparent.
#
import subprocess
import sys
USAGE = """
USAGE: winpylaunch.py <script.py> [arg1] [arg2...]
"""
if __name__ == "__main__":
if len(sys.argv) > 1:
script = sys.argv[1]
args = sys.argv[2:]
if script.endswith(".py"):
interpreter = "python.exe" # Default to wherever it is found on the path.
lines = open(script).readlines()
for line in lines:
if line.startswith("#!") and line.find(".exe") != -1:
interpreter = line[2:].strip()
break
process = subprocess.Popen([interpreter] + [script] + args)
process.wait()
sys.exit()
print(USAGE)
I've just knocked this up on reading this thread (because it's what I was needing too). I have Pythons 2.6.1 and 3.0.1 on both Ubuntu and Windows. If it doesn't work for you post fixes here.
Try using Anaconda.
Using the concept of Anaconda environments, let’s say you need Python 3 to learn programming, but you don’t want to wipe out your Python 2.7 environment by updating Python. You can create and activate a new environment named "snakes" (or whatever you want), and install the latest version of Python 3 as follows:
conda create --name snakes python=3
Its simpler than it sounds, take a look at the intro page here: Getting Started with Anaconda
And then to handle your specific problem of having version 2.x and 3.x running side by side, see:
Managing Python Versions with Anaconda
Switching between Python 2 and Python 3 environments
As far as I know Python runs off of the commandline using the PATH variable as opposed to a registry setting.
So if you point to the correct version on your PATH you will use that. Remember to restart your command prompt to use the new PATH settings.
The Python installation normally associates .py, .pyw and .pyc files with the Python interpreter. So you can run a Python script either by double-clicking it in Explorer or by typing its name in a command-line window (so no need to type python scriptname.py, just scriptname.py will do).
If you want to manually change this association, you can edit these keys in the Windows registry:
HKEY_CLASSES_ROOT\Python.File\shell\open\command
HKEY_CLASSES_ROOT\Python.NoConFile\shell\open\command
HKEY_CLASSES_ROOT\Python.CompiledFile\shell\open\command
Python Launcher
People have been working on a Python launcher for Windows: a lightweight program associated with .py and .pyw files which would look for a "shebang" line (similar to Linux et al) on the first line, and launch Python 2.x or 3.x as required. See "A Python Launcher for Windows" blog post for details.
Here is how to run Python 2 and 3 on the same machine
install Python 2.x
install Python 3.x
Start Powershell
Type Python -2 to launch Python 2.x
Type Python -3 to launch Python 3.x
The Python Launcher for Windows was embedded into Python since Version 3.3, as promised in 2011 when the Stand alone first made its debut:
Python Launcher for Windows
Easy-peasy ,after installing both the python versions add the paths to the environment variables ;see. Then go to python 2 and python 3 folders and rename them to python2 and python3 respectively as shown and . Now in cmd type python2 or python3 to use your required version see .
I think there is an option to setup the windows file association for .py files in the installer. Uncheck it and you should be fine.
If not, you can easily re-associate .py files with the previous version. The simplest way is to right click on a .py file, select "open with" / "choose program". On the dialog that appears, select or browse to the version of python you want to use by default, and check the "always use this program to open this kind of file" checkbox.
You should make sure that the PATH environment variable doesn't contain both python.exe files ( add the one you're currently using to run scripts on a day to day basis ) , or do as Kniht suggested with the batch files .
Aside from that , I don't see why not .
P.S : I have 2.6 installed as my "primary" python and 3.0 as my "play" python . The 2.6 is included in the PATH . Everything works fine .
Before I courageously installed both simultaneously, I had so many questions. If I give python will it go to py3 when i want py2? pip/virtualenv will happen under py2/3?
It seems to be very simple now.
Just blindly install both of them. Make sure you get the right type(x64/x32).
While/after installing make sure you add to the path to your environment variables.
[ENVIRONMENT]::SETENVIRONMENTVARIABLE("PATH", "$ENV:PATH;C:\PYTHONx", "USER")
Replace the x in the command above to set the path.
Then go to both the folders.
Navigate to
python3.6/Scripts/
and rename pip to pip3.
If pip3 already exists delete the pip. This will make sure that just pip will run under python2. You can verify by:
pip --version
In case you want to use pip with python3 then just use
pip3 install
You can similarly do the same to python file and others.
Cheers!
I had the same problem where I wanted to use python3 for most work but IDA pro required python2. SO, here's what I did.
I first created 3 variables in the user environment variable as follows:
PYTHON_ACTIVE : This is initially empty
HOME_PYTHON27 : Has a path to a folder where Python 2 is installed. Eg. ";/scripts;"
HOME_PYTHON38 : Similar to python 2, this variable contains a path to python 3 folders.
Now I added
%PYTHON_ACTIVE%
to PATH variable. So, basically saying that whatever this "PYTHON_ACTIVE" contains is the active python. We programmatically change the contains of "PYTHON_ACTIVE" to switch python version.
Here is the example script:
:: This batch file is used to switch between python 2 and 3.
#ECHO OFF
set /p choice= "Please enter '27' for python 2.7 , '38' for python 3.8 : "
IF %choice%==27 (
setx PYTHON_ACTIVE %HOME_PYTHON27%
)
IF %choice%==38 (
setx PYTHON_ACTIVE %HOME_PYTHON38%
)
PAUSE
This script takes python version as input and accordingly copies HOME_PYTHON27 or HOME_PYTHON38 to PYTHON_ACTIVE. Thus changing the global Python version.
I would assume so, I have Python 2.4, 2.5 and 2.6 installed side-by-side on the same computer.
I am just starting out with python now. I'm reading Zed Shaw's book "Learn Python the Hard Way" which requires python version 2.x but am also taking a class that requires python 3.x
So here is what I did.
Download python 2.7
run power shell (should already be installed on windows)
run python IN POWERSHELL (if it doesn't recognize then go to step 4)
Only if powershell doesn't recognize python 2.7 type in the following:
"[ENVIRONMENT]::SETENVIRONMENTVARIABLE("PATH", "$ENV:PATH;C:\PYTHON27", "USER")"
(no outside quotes)
Now type python and you should see it say python 2.7 blah blah blah
NOW for python 3.x
Simple, python 3.x download comes with python for windows app. SO simply pin the Python for Windows app to your task bar, or create shortcut to the desktop and you are done!
Open Python for Windows for 3.x
Open Powershell for python 2.x
I hope this helps!
Hmm..I did this right now by just downloading Python 3.6.5 for Windows at https://www.python.org/downloads/release/python-365/ and made sure that the launcher would be installed. Then, I followed the instructions for using python 2 and python 3. Restart the command prompt and then use py -2.7 to use Python 2 and py or py -3.6 to use Python 3. You can also use pip2 for Python 2's pip and pip for Python 3's pip.
mySQL seems to be up and running just fine. But when I try to import MySQLdb into python I get a ImportError: ... Expected in: flat namespace. I think it has to do with having two different versions for python (well two different directories, same version)
OS: Mac 10.6.8
$ ls /Library/Frameworks/Python.framework/Versions/
7.2 Current
$ which python
/Library/Frameworks/Python.framework/Versions/Current/bin/python
$ echo $PATH
/Library/Frameworks/Python.framework/Versions/Current/bin:/Library/Frameworks/Python.framework/Versions/2.7/bin:/Library/Frameworks/Python.framework/Versions/2.7/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/local/git/bin:/usr/X11/bin
$ easy_install MySQL-python
...
...
Using /Library/Frameworks/Python.framework/Versions/7.2/lib/python2.7/site-packages/MySQL_python-1.2.3-py2.7-macosx-10.5-i386.egg
...
$ mysql.server start
Starting MySQL
.. SUCCESS!
$ python manage.py runserver
...
...
django.core.exceptions.ImproperlyConfigured: Error loading MySQLdb module: dlopen(/Library/Frameworks/Python.framework/Versions/7.2/lib/python2.7/site-packages/MySQL_python-1.2.3-py2.7-macosx-10.5-i386.egg/_mysql.so, 2): Symbol not found: _mysql_affected_rows
Referenced from: /Library/Frameworks/Python.framework/Versions/7.2/lib/python2.7/site-packages/MySQL_python-1.2.3-py2.7-macosx-10.5-i386.egg/_mysql.so
Expected in: flat namespace
in /Library/Frameworks/Python.framework/Versions/7.2/lib/python2.7/site-packages/MySQL_python-1.2.3-py2.7-macosx-10.5-i386.egg/_mysql.so
$ python
Enthought Python Distribution (EPD) free version -- www.enthought.com
Version: 7.2-2 (32-bit)
>>> import MySQLdb
...
...
ImportError: dlopen(/Library/Frameworks/Python.framework/Versions/7.2/lib/python2.7/site-packages/MySQL_python-1.2.3-py2.7-macosx-10.5-i386.egg/_mysql.so, 2): Symbol not found: _mysql_affected_rows
Referenced from: /Library/Frameworks/Python.framework/Versions/7.2/lib/python2.7/site-packages/MySQL_python-1.2.3-py2.7-macosx-10.5-i386.egg/_mysql.so
Expected in: flat namespace
in /Library/Frameworks/Python.framework/Versions/7.2/lib/python2.7/site-packages/MySQL_python-1.2.3-py2.7-macosx-10.5-i386.egg/_mysql.so
So in addition to being new to django and python I'm also new to using the terminal, and I'm not exactly sure what I'm looking at.
But I can tell the obvious:
I have two versions, 7.2 and current.
If I call python it will call the 'Current' version. That makes sense, it's in $PATH.
However, a version 2.7 (not 7.2) is also in PATH which I had deleted when I installed the EDP package. ...I don't fully understand what PATH is or does so I didn't want to start changing things
MySQL-python is installed in version 7.2
Can't run the server because a necessary file isn't in flat namespace and it's at the place it was installed too
Is there some way to untangle these paths (if that's the problem)
thank you in advance
Well... I don't think it had anything the do with the "Current" and "7.2" versions of python.
It seems to have fixed itself after doing
pip uninstall MySQL-python
brew uninstall mysql
brew install mysql --universal
pip install MySQL-python
I'm not sure if the --universal made the diference or using pip install as opposed to easy_install