127 lines
2.6 KiB
Markdown
127 lines
2.6 KiB
Markdown
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---
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title: How to use virtual environments
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date: 2022-06-19
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lastmod: 2022-06-19
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tags: code
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Tags: [python, R, julia]
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slug: using-virtual-environments
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author: Samuel Ortion
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lang: en
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status: published
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---
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To not interfere with your os configuration and keep your project reproducible, you should use a virtual environment as long as possible.
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Virtual environment are a way to isolate your project from the rest of the system, and to avoid dependencies conflicts.
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## Python Virtualenv
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Lets start by installing the virtualenv package.
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```bash
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sudo apt install python3-venv
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```
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And now you can create venvs for your project:
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```bash
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python3 -m venv .venv/myproject
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```
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It is a good practice not to create a virtualenv with name "venv", but to use a name that reflects the project you are working on, in order to see directly in which venv you are working.
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Now you can activate the virtualenv:
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```bash
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source .venv/myproject/bin/activate
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```
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And deactivate it when you are done:
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```bash
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deactivate
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```
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One other way to create a virtualenv is to use the `virtualenv` command.
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Once you installed python packages, you should create a snapshot of your project dependencies using:
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```bash
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pip freeze > requirements.txt
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```
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That way, you can allow other people to use your project and installi its dependencies with the following command:
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```bash
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pip install -r requirements.txt
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```
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You could also use conda, as a package manager, to create a virtualenv.
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## R Virtualenv
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R also has its own virtualenv gestionnal system named packrat.
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First install packrat with R.
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```R
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install.packages("packrat")
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```
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And create your virtual environment with:
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```R
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packrat::init("myproject")
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```
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Similarly, you can then install packages:
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```R
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install.packages("dplyr")
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```
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And create a snapshot of your dependencies with:
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```R
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packrat::snapshot()
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```
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The dependency list is available in `packrat/packrat.lock`.
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## Julia Virtualenv
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Julia venv is very similar to Python venv.
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First, you install the VirtualEnv package:
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```bash
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julia -e 'using Pkg; Pkg.add("VirtualEnv")'
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```
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And add `~/.julia/bin` to your path:
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```bash
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julia -e 'using VirtualEnv; VirtualEnv.comonicon_install_path()'
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```
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Then you can use `venv` to create a virtualenv for your project:
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```bash
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venv .venv/myproject
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```
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And you can activate/deactivate it:
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```bash
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source .venv/myproject/bin/activate
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deactivate
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```
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That's it !
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## References
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- [Python venv documentation](https://docs.python.org/3/library/venv.html)
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- [Packrat documentation](https://rstudio.github.io/packrat/)
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- [Julia venv documentation](https://juliapackages.com/p/virtualenv)
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