I've been using virtual environment successfully for some time, but this is the first time i run into such a problem.
In my virtual environment i have Python 3.5 + Django package + number of other packages. I successfully run my Django app using Python 3.5 from virtual environment on machine A.
On machine B, after I source env/bin/activate my virtual environment. python command would start Python 2.7 + no Django package present.
How do i investigate this and make venv behave in same way on both machines?
There are two options to get the same Python version in a virtual environment.
Check if there's Python 3.5 installed on your machine by typing
python3 -V
into the command line. If it says 3.5.x you can go on and create a virtual environment with
pyvenv /path/to/your/new/venv
You may install your packages (Django, etc.):
on machine A
pip freeze > requirements.txt
transfer requirements.txt to machine B and do
source /path/to/your/new/venv/bin/activate
pip install -r requirements.txt
If the python version that you've checked in 1. is not 3.5.x you have to compile this version by yourself. Check this question Use different Python version with virtualenv
Related
I am trying to create a virtual environment to run a script which requires Python 3.6. I started off with Pipenv but I am unable to create the same environment on other platforms via the Pipfile.lock or requirements.txt unless the other platform(s) has Python 3.6 installed. I have read this post but I am unsure which direction I should take to create a virtual environment which can be shared and run its own version of Python independent of operating system and version of Python installed on the other platform.
Virtual environments are not portable, they depend on the Python installation you have.
You can't share/distribute virtual environment with others, because you can't control which version of Python others are using.
If you want to distribute your code along with all dependencies including the specific version of Python interpreter, you can use PyInstaller. It is far from perfect and little bit hacky. Also it generates a package which is specific to operating system.
https://pyinstaller.readthedocs.io/en/stable/operating-mode.html
There is also a detailed step-by-step guide on how to use PyInstaller.
https://realpython.com/pyinstaller-python/
This is step-by-step how I use Python virtual environment and share it with co-workers.
To check python and virtualenv presence, run following commands:
which python3
python3 -m pip list | grep env
which virtualenv
Install a python virtual environment builder:
python3 -m pip install virtualenv
Create a virtual environment named venv inside the project's directory: virtualenv venv
To activate this environment use this command inside project's directory: source venv/bin/activate
Install python modules dependencies listed in a requirements.txt:
python3 -m pip install -r requirements.txt
You should activate virtual environment when you working with python in this directory for package installation and for running commands in the project directory. When you need to deactivate the virtual environment do it using deactivate command.
To deactivate environment simply run: deactivate
To run some script I need specific version of python (3.7.1).
On my PC I have python 3.7.3
For creating virtual environment I am using:
python -m venv virtual
Which gives me fully functional python but in version 3.7.3 and I need 3.7.1
How can this be achieved?
virtualenv can only create environments for versions of python installed on the machine.
You may install multiple versions in parallel on windows then select which one to use.
Just install Python 3.7.1. Assuming you are using virtualenv, create your environment as:
virtualenv -p /home/username/opt/python-3.7.1/bin/python Project_Name
I have installed Python 2.7, pip and virtualenv on my computer and I have created a virtual environment with this same version of Python. I installed some packages in this new virtual environment too.
Later, I decided to install Python 3.6 on the same computer to create a virtual environment that works with version 3.6. I downloaded Python 3.6 and installed it by selecting Add Python 3.6 to PATH and Install for All users and I selected the option to automatically install pip. As I had previously installed virtualenv, I have not had to reinstall it. Should I?
The problem is that, once installed, when creating a virtual environment I've got an error.
As I already had a version of Python installed I have specified that I want to use Python 3.6 in the virtual environment that I am creating:
virtualenv env2_py36 -p c: \ Python36 \ python.exe
The error already says that this usually happens when you install more than one version of Python on the same computer and warns that it is necessary to check the option Install for All Users to work (as I did) and also recommends placing the appropiate PythonXX.dll file in the Scripts folder of the virtual environment. However, I see that there is already a python36.dll file there.
Could anybody tell me what should I do to fix this problem?
On the other hand, I had previously created another virtual environment using Python 2.7. I use PyScripter to run my scripts but I don't know how to connect PyScripter to my virtual environment. It's still connected to the Python2.7's system installation.
This works for me:
virtualenv --python=python3.6 yourenvname
(3.6 is the current latest version of Python, but you can use whichever version you'd like.)
How can I switch from virtualenv that uses python 2.7 to python virtualenv that uses python 3.5?
Migration from 2.x to 3.x Python has nothing to do with virtualenv. If you already built your project keeping in mind a version change, then it will not be hard.
You can just download the Python35 and install it. After that, just execute
virtualenv -p /path to your Python35 directory/python.exe name_of_env
to create a new virtual environment for Python3.5. You can imagine the new virtual environment as a fresh Python installation with no third packages.
Please note that virtualenv just creates a new environment inside your computer with the Python version you specified in the -p parameter (or if omitted the Python version that is specified in your Path).
You can then install the desired packages for your project after activating the new virtual environment (./name_of_env/Scripts/activate) by executing pip install package_name
Although keep in mind that version migration is not the simplest thing. Many things can go wrong and especially the packages version support. Most of the packages support Python 3.x but not all of them.
Using Python I require both python 2.7 and python 3.5 for different packages. I am trying to install the following package NepidemiX. I get an error when I do this as I have a newer version of python installed.
To combat this I am trying to create a virtual environment. To do this I am using the virtualenv package.
I have created and activated this and am now faced with
(my_project)Your-Computer:your_project UserName$)
In my terminal.
How do I now proceed to install my package from here? Do I need to install python 2.7 in this environment first, or do I simply copy the desired package into the environment ... ?
Please could you instruct me how to correctly set this up?
Many thanks!
Virtual environment is only for libraries. It uses python versions installed on your computer. You can specify the version of python by using the -p attribute while creating the environment, for ex. virtualenv -p python3 env creates a python 3 enviroment (provided you have it installed in your computer and on the PATH). Check this answer.
After you activate the environment (source /env/bin/activate), just pip install libraries, and the environment takes care of installing the correct version.