python<\/code> to invoke Python 3 interpreter.<\/p>\nActivating and using a virtual environment or venv<\/h2>\n
To start using the virtual environment, we need to import a script located at $HOME\/my-venv\/bin<\/code> into our SHELL environment. This script will be add the virtual environment\\'s directory to your shell\\'s PATH environment such that when python<\/code> or pip<\/code> or other packages are searched for the SHELL will search the virtual environment\\'s directory first search the my-venv<\/code> directory to look for appropriate python program.<\/p>\nDepending on your SHELL the script you need to invoke will be different. For bash<\/code>, and zsh<\/code> interpreters the script is named activate<\/code>:<\/p>\nroot@node-00:~# source ~\/my-venv\/bin\/activate\n(my-venv) root@node-00:~#<\/code><\/pre>\nFor fish<\/code> shell the script is called activate.fish<\/code> and there is a similar script for tsch<\/code> in the same directory. For Windows 10, the scripts will have a .bat<\/code> and .ps1<\/code> extensions for command prompt and powershell respectively. Use the command echo $SHELL<\/code> to know what shell your system is using.<\/p>\nNotice in the above shell, once the venv<\/code> is activated the prompt changed. It also has a copy of pip<\/code> install by default. You can verify this and even update it:<\/p>\n$ pip --version\npip 20.0.2 from \/root\/my-venv\/lib\/python3.8\/site-packages\/pip (python 3.8)<\/code><\/pre>\nTo list all the packages installed, and to update them just do the following:<\/p>\n
$ pip list\nPackage Version\n------------- -------\npip 20.0.2\npkg-resources 0.0.0\nsetuptools 44.0.0\n\n$ pip install --upgrade pip pkg-resources setuptools\n$ pip list\nPackage Version\n------------- -------\npip 21.0.1\npkg-resources 0.0.0\nsetuptools 56.0.0<\/code><\/pre>\nThis won\\'t update your system\\'s copy of pip<\/code> or any other pip package you have installed system-wide. The version of Python being used is the same as the Python command used to create your virtual environment.<\/p>\nYou can install any number of pip<\/code> packages inside this environment and use it for your Python projects. As long as the environment is active, the Python interpreter will prioritize these packages when your scripts call for a specific module, regardless of where you are in your filesystem. Once you are done working on the project, and want to switch gears simply type in deactivate<\/code> and the virtual environment will be disabled:<\/p>\n(my-venv) root@node-00:~# deactivate\nroot@node-00:~#<\/code><\/pre>\nNotice that the prompt is back to being normal. You can always reactivate the venv by running the source<\/code> command along with the activate<\/code> script. If your environment is broken simply remove the directory to get rid of it. Make sure that your Python project's file don't live in the same directory as the virtual environment.<\/p>\nNote on Updating Packages and Portability<\/h2>\n
Once you have installed necessary packages, it is always important to keep a snapshot of all the packages and their version numbers. This allows you to maintain and upgrade things gradually without the risk of things breaking down.<\/p>\n
$ pip freeze > requirements.txt<\/code><\/pre>\nBy convention the requirements.txt<\/code> file is used to store all the packages. Here's a typical output:<\/p>\nclick==7.1.2\ncycler==0.10.0\njoblib==1.0.1\nkiwisolver==1.3.1\nmatplotlib==3.4.1\nnltk==3.6.1\nnumpy==1.20.2\nPillow==8.2.0\npyparsing==2.4.7\npython-dateutil==2.8.1\nregex==2021.4.4\nsix==1.15.0\ntextblob==0.15.3\ntqdm==4.60.0<\/code><\/pre>\nIt also allows you to:<\/p>\n
\n- Recreate the environment quickly and exactly, even if the underlying packages update in the future. Reinstall the same packages using the following command:\n
$ pip install -r requirements.txt<\/code><\/pre>\n<\/li>\n- Keep track of the dependencies with your version control like git or GitHub.<\/li>\n
- Reuse the file for other parts of your CI\/CD like when creating a Docker image for your file.<\/li>\n<\/ul>\n
That\\'s it for Python environments! Happy computing!<\/p>\n","protected":false},"excerpt":{"rendered":"
Dependency hell Without virtual environments, working with Python is a nightmare! In case of Ubuntu, the base operating system comes with Python preinstalled, and you might think that that\\’s a nice thing. Except, that version of Python is old and pip is not even installed. So you install pip only to find out that it …<\/p>\n","protected":false},"author":20,"featured_media":6075,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"inline_featured_image":false,"footnotes":""},"categories":[18,30],"tags":[213,214],"class_list":["post-5841","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-devops","category-tutorials","tag-python","tag-venv"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.ssdnodes.com\/wp-json\/wp\/v2\/posts\/5841","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.ssdnodes.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.ssdnodes.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.ssdnodes.com\/wp-json\/wp\/v2\/users\/20"}],"replies":[{"embeddable":true,"href":"https:\/\/www.ssdnodes.com\/wp-json\/wp\/v2\/comments?post=5841"}],"version-history":[{"count":2,"href":"https:\/\/www.ssdnodes.com\/wp-json\/wp\/v2\/posts\/5841\/revisions"}],"predecessor-version":[{"id":13068,"href":"https:\/\/www.ssdnodes.com\/wp-json\/wp\/v2\/posts\/5841\/revisions\/13068"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.ssdnodes.com\/wp-json\/wp\/v2\/media\/6075"}],"wp:attachment":[{"href":"https:\/\/www.ssdnodes.com\/wp-json\/wp\/v2\/media?parent=5841"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ssdnodes.com\/wp-json\/wp\/v2\/categories?post=5841"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ssdnodes.com\/wp-json\/wp\/v2\/tags?post=5841"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
![\"Python](\"https:\/\/imgs.xkcd.com\/comics\/python_environment.png\" "\\"Python")
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