How to create virtual env with python3 - python

I am using python 2.7 + virtualenv version 1.10.1 for running myproject projects. Due to some other projects requirement I have to work with other version of python(Python 3.5) and Django 1.9. For this I have installed python in my user directory. Also I have dowloaded and installed virtualenv( version - 15.1.0) into my user directory.
But whenever I am trying to create virtual env I am getting the below error
python virtualenv/virtualenv.py myproject
Using base prefix '/home/myuser/python3'
New python executable in /home/mount/myuser/project_python3/myproject/bin/python
ERROR: The executable /home/mount/myuser/project_python3/myproject/bin/python is not functioning
ERROR: It thinks sys.prefix is '/home/myuser/python3' (should be '/home/mount/myuser/project_python3/myproject')
ERROR: virtualenv is not compatible with this system or executable
Can anybody tell what I am doing wrong with this

In Python 3.6+, the pyvenv module is deprecated. Use the following one-liner instead:
python3 -m venv <myenvname>
This is the recommended way to create virtual environments by the Python community.

To create virtual env
virtualenv -p python3 venv_name
This will create new python executable in baseDirectory/bin/python3
How to activate newely created Venv:
cd baseDirectory/bin/
source activate
Deactivate new venv
deactivate
UPDATE_1
This method has been depreciated as The use of venv is now recommended for creating virtual environments.
Please check this link for updated answer

Python already ships with its builtin "virtualenv" called venv since version 3.3. You no longer need to install or download the virtualenv scripts for Python 3.3+.
https://docs.python.org/3/library/venv.html
Check that your installation provided the pyvenv command that should take care of creating the "virtualenv". Arguments are similar to the classic virtualenv project.
$ pyvenv --help
usage: venv [-h] [--system-site-packages] [--symlinks | --copies] [--clear]
[--upgrade] [--without-pip]
ENV_DIR [ENV_DIR ...]
Creates virtual Python environments in one or more target directories.
positional arguments:
ENV_DIR A directory to create the environment in.
optional arguments:
-h, --help show this help message and exit
--system-site-packages
Give the virtual environment access to the system
site-packages dir.
--symlinks Try to use symlinks rather than copies, when symlinks
are not the default for the platform.
--copies Try to use copies rather than symlinks, even when
symlinks are the default for the platform.
--clear Delete the contents of the environment directory if it
already exists, before environment creation.
--upgrade Upgrade the environment directory to use this version
of Python, assuming Python has been upgraded in-place.
--without-pip Skips installing or upgrading pip in the virtual
environment (pip is bootstrapped by default)
Once an environment has been created, you may wish to activate it, e.g. by
sourcing an activate script in its bin directory.

virtualenv is the tool of choice for Python 2, while venv handles the task in Python 3.
Yet you can create the virtual environment for Python 3 using any of them.
Using venv
python3 -m venv virtualenvname
Command Syntax:
/path/to/python3 -m venv /path/to/directory/virtual_env_name
Using virtualenv
virtualenv -p python3 virtualenvname
Command Syntax:
virtualenv -p /path/to/python3 /path/to/directory/virtual_env_name
Activate the virtual environment
On Linux, Unix or MacOS, using the terminal or bash shell:
source /path/to/venv/bin/activate
e.g. source virtualenvname/bin/activate
On Unix or MacOS, using the csh shell:
source /path/to/venv/bin/activate.csh
On Unix or MacOS, using the fish shell:
source /path/to/venv/bin/activate.fish
On Windows using the Command Prompt:
path\to\venv\Scripts\activate.bat
On Windows using PowerShell:
path\to\venv\Scripts\Activate.ps1
Deactivating the virtual environment
On Linux, Unix or MacOS, using the terminal or bash shell:
deactivate
On Windows using the Command Prompt:
path\to\venv\Scripts\deactivate.bat
On Windows using PowerShell:
deactivate
This answer is for those who may use a different OS.

Since the launch of Python version 3.3, there has been no need to download the virtualenv package separately as it comes built-in in Python.
Refer to the documentation to gain complete insights on it.
Test the installation of virtualenv:
$ virtualenv --version
Usage:
1.Creating a virtual environment:
$ virtualenv --system-site-packages -p python3 ./virtual_env_name
2.For enabling it, use the following command:
$ source ./virtual_env_name/bin/activate
3.For disabling the virtual environment and get back to working with the local environment:
$ deactivate
For listing down the packages in the virtual environment, use the
following command:
$ pip3 list

I install it using the command (for Python 3.x),
$ python3 -m venv env

To create a virtual environment in python3:
virtualenv -p /usr/bin/python3 virtualenvname
After creating the virtual environment, we need to activate it using the below command:
source virtualenvname/bin/activate
to deactivate use the below command:
deactivate

If you are on windows.
manually download and install the version of python you want from the official site
after installation, search "python" to locate the folder, so you can identify the path
get the path of the .exe (for example: C:\Users\Path\Programs\Python\Python38\python.exe)
Inside the folder of which you want to create the environment...start bash or VSCode terminal, or whatever command prompt, type [python .exe path] -m venv [env name] like this:
C:/Users/Path/Programs/Python/Python38/python.exe -m venv myenv
(Note that you have to change forward slash to backward slash for the path on step 4)
Activate the environment like so:
source myenv/Scripts/activate

Install virtualenvwrapper on top of virtualenv to simplify things.
Follow the blog to install in easy steps: virtualenvwrapper
Steps to create it:
mkvirtualenv -p /usr/bin/python3
Install packages using - pip install package_name
workon - activates the virtualenv, deactivate - deactivates the viirtualenv

Related

How to create a Python virtual environment independent of OS and Python version

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

install packages in Python2 with Python3

I am trying to install numpy, nltk, etc packages for Python 2 to run a code. But I have Python3 as well and the path variable is set to it. When I try to use any pip install command it shows the package is available in Python3's directory.
Also, I am using VSCode, so I did not add the path variable.
I suggest you use virtual environments. Because if you read about virtual environments, you will find that they are created for such cases.
To create virtual environments, you must do the following:
Make a note of the full file path to the custom version of Python you just installed.
virtualenv -p /home/username/opt/python-2.7.15/bin/python venv
In order to use this environment’s packages/resources in isolation, you need to “activate” it. To do this, just run the following:
source venv/bin/activate (Linux)
./venv/Scripts/activate.bat (Windows)
Notice how your prompt is now prefixed with the name of your environment (venv, in our case). This is the indicator that venv is currently active, which means the python executable will only use this environment’s packages and settings.
Now run the following:
(venv) $ which python
/Users/ashkan/python-virtual-environments/venv/bin/python (in my case)
now you have access to python2.7.
The best practice for this particular problem would be virtual environments.And for that matter Pipenv would be a good option.
Install Pipenv.
$ brew install pipenv (MacOs)
$ sudo apt install pipenv (Debian)
$ sudo dnf install pipenv (Fedora)
pip install pipenv (Windows)
Creating virtual env with Pipenv.
pipenv install --python 2.7 numpy
This command will install create a virtual environment and install python 2.7(which will be used as the main interpreter once you activate the environment) along with numpy in that environment. This will avoid the packages version conflicts too.
To activate the environment
pipenv shell
If you are working in the Vs Code workspace then you should set the interpreter path(python path) to the path of the virtual environment.
when we install anything using pip. it will install dependencies for default python version. so you can change the default python version using this link https://linuxconfig.org/how-to-change-from-default-to-alternative-python-version-on-debian-linux
Hope this will solve your problem
After crating a virtual environment with python 2.7 you can install your required packages

python3 -m venv: how to specify Python point release/version?

To create a virtual environment using virtualenv you can specify the Python release and point version like so:
virtualenv --python=python3.6 .venv
How can I achieve this using Python3's venv module (as in python3 -m venv .newvenv)? According to the documentation using venv is the recommended way to create virtual environments but I didn't see how I can choose a virtual environement with a specific Python version.
Run venv with whatever Python installation you want to use for the new virtual environment. For example, if you would run your Python 3.6 installation with python3.6, then
python3.6 -m venv whatever
would be how you create a Python 3.6 virtual environment.
I thought to add to this answer when one is using pyenv. In my workflow I use pyenv to have multiple python versions but not to manage virtualenvs. I rather have my python virtual environment in the project's root. With pyenv one can install multiple python versions by running pyenv install 3.8.10 and after that pyenv install 3.9.0. When you run pyenv versions you should get something similar to this
system
* 3.8.10 (set by /Users/<user>/.pyenv/version)
3.8.10/envs/python-test.venv
3.9.0
When working on a project and choosing what python version should be used in that project you can do the following.
$ mkdir my_project && cd my_project
$ pyenv global <version>
$ python --version // should be the version you set as global
$ python -m venv .venv
$ source .venv/bin/activate
I was able to avoid error mentioned in the comments by using the option --without-pip. Then after activating the venv, I installed pip manually with the get-pip.py script.

How to active a virtualenv with pyenv installed

I use pyenv for handling my python versions. I also use virtualenv for creating my virtual environments. In a new project, I made a new virtual environment with python -m venv venv to make a directory called venv that has a fresh python 3.6. I then did source venv/bin/activate expecting that to make venv/bin/python to be my default python from this directory, but when I do command -v python, I am told that /Users/TheStrangeQuark/.pyenv/shims/python is still the path. I also checked with python -c "import sys; print(sys.executable)" and was printed with /Users/jhuneau/.pyenv/versions/3.6.2/bin/python.
Why is source venv/bin/activate not working to set the python executable in this directory to use the virtual environment?
I think you should try:
source venv/bin/activate
instead of
source venv/bin/active

How to use a Python virtual env in my Ubuntu bash?

I am trying to package my project with a virtual env so that it is easier to implement.
I am trying to do this in a Ubuntu bash.
I have succesfully created a Python venv using the Python virtualenv library.
I do manage to activate it using source venv_name/bin/activate.
I can indeed see (venv_name) at the beginning of my command line.
However, I do not manage to actually use this virtual environment.
I have for proof that when I type which python3 I get my root python3; and I have tried to update a package in the virtualenv but it has been updated in the root python.
What should I do to actually use my virtual env ? For now I am trying:
python3 myscript.py
And it is working but I suspect it's running with my root python3.
I think you have two versions of python (2 and 3). You create virtualenv with python 2. Recreate virtualenv with correct python version
You have to make next steps to use python3 virtual environment in Ubutnu:
1. Install virtual environment lib for python3 with command:
pip3 install virtualenv
2. Create your virtual environment:
python3 -m venv venv
3. Activate it:
source venv/bin/activate
Works correct for me in Ubutnu 16.04

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