84 lines
1.9 KiB
Markdown
84 lines
1.9 KiB
Markdown
---
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tags: [python, data-types]
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---
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# Package management
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- You can use `conda` (the package manager that comes with `anaconda`). This
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makes it easier to work with conflicting package libraries (a bit like a
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package lock).
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- The alternative is the native `pip` but you have to create virtual
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environments (`venv`) to manage packages at different versions.
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## venv
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To make use of virtual environments in `pip` you have to create the virtual
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environment before installing anything:
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```
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python3 -m venv venv
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```
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This will create a `venv` directory in your project that will manage the
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handling of modules.
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> This is especially important in ArchLinux since without a virtual environment
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> it will ask you to install packages with `pacman` which is annoying for local
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> packages.
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You then activate the environment with:
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```
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source venv3/bin/activate
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```
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Now you can install packages:
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```
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pip [library_name]
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```
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### Using venv after a system upgrade
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If you update your system's version of Python, this can cause `venv` to stop
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working. Resolve as follows:
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```
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deactivate # leave venv env if in it
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rm -rf venv # remove venv
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python -m venv venv # reinstall venv
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source venv/bin/activate
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python -m ensurepip --upgrade # explicitly install pip
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pip install - e.
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```
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## requirements.txt
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The `requirements.txt` file is similar to the `package.json` in Node projects.
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Each line of the `requirements.txt`` file specifies a package that your project
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depends on and, optionally, the desired version of that package. When you share
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your project with others or move it between different environments (e.g., from
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development to production), this file makes it easy to set up your environment
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with the right dependencies.
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### Example
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```
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Flask==1.1.2
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requests>=2.24.0
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numpy~=1.19.2
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pandas
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```
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### Generate requirements file
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```
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pip freeze > requirements.txt
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```
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## Pypy
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- pypi.org is package registry like NPM
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