\t\t\t\tIn this post we will discuss the concept of a Virtual Environment in Python.
\nWe will discuss the following topics:<\/p>\n
What is a virtual environment?<\/strong> Setting-up the virtual environment<\/strong> The parent python distribution contains the pyvenv<\/em> executable which is used to create the virtual environment: Activation of the virtual environment<\/strong> In the following snippet of code (vide infra) we check whether the child distribution can indeed use the numpy functionality from the parent distribution: Installation of packages within the virtual environment<\/strong><\/p>\n In this section we explain how to install packages in the newly created virtual environment. We will install 2 packages using ‘pip install<\/em>‘ (Example 1) and ‘setup.py<\/em>‘ (Example 2).<\/p>\n Note that the pip executable is NOT installed in the newly created ~\/MyVenv\/bin directory. We will now show how to do some simple installations in our virtual environment:<\/p>\n Note that we are not required to use the –prefix flag, because Deactivation of the Virtual Environment<\/strong> Removal of the Virtual Environment<\/strong> In this post we will discuss the concept of a Virtual Environment in Python. We will discuss the following topics: What is a Virtual Environment (VE) Setting up a VE Activation of a VE Installation of packages within the VE Deactivation of a VE Removal of a VE What is a virtual environment? A Python […]<\/p>\n","protected":false},"author":3,"featured_media":643,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2],"tags":[30,37,39],"class_list":["post-625","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-experience","tag-python","tag-venv","tag-virtual-environment"],"_links":{"self":[{"href":"https:\/\/aciref.chpc.utah.edu\/index.php?rest_route=\/wp\/v2\/posts\/625","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/aciref.chpc.utah.edu\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/aciref.chpc.utah.edu\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/aciref.chpc.utah.edu\/index.php?rest_route=\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/aciref.chpc.utah.edu\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=625"}],"version-history":[{"count":0,"href":"https:\/\/aciref.chpc.utah.edu\/index.php?rest_route=\/wp\/v2\/posts\/625\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/aciref.chpc.utah.edu\/index.php?rest_route=\/wp\/v2\/media\/643"}],"wp:attachment":[{"href":"https:\/\/aciref.chpc.utah.edu\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=625"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/aciref.chpc.utah.edu\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=625"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/aciref.chpc.utah.edu\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=625"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
\nA Python virtual environment is a child\/offshoot of a parent python distribution which allows you to use the packages in the parent distribution as well as to install packages that are only visible to the child distribution (cfr. inheritance in OO).<\/p>\n
\nIn the first step, we load the parent python distribution in our environment.
\nThe parent python distribution (in this example) is python 3.3.6 (built from source).
\nWithin the parent python distribution an array of packages have been installed: numpy, scipy, matplotlib, etc.<\/p>\n[u0253283@dirac ~]$ module load python\/3.3.6\u00a0\u00a0 # Loading python 3.3.6 using LMOD
\n[u0253283@dirac ~]$ which python3\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 # Check the executable
\n\/uufs\/chpc.utah.edu\/sys\/installdir\/python\/3.3.6\/bin\/python3<\/span><\/code><\/p>\n[u0253283@dirac ~]$ python3 --version\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 # Version of python3
\nPython 3.3.6<\/span><\/code><\/p>\n
\n[u0253283@dirac ~]$ which pyvenv\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 # Check the version of pyvenv
\n\/uufs\/chpc.utah.edu\/sys\/installdir\/python\/3.3.6\/bin\/pyvenv<\/span><\/code><\/p>\npyvenv --system-site-packages ~\/MyVenv<\/span><\/code>
\nThe newly created virtual environment resides in the directory $HOME\/MyVenv. The flag ‘–system-site-packages’ grants access to the parent site-packages dir.<\/p>\n
\nIn order to use the virtual environment, we first need to unload the parent python distribution. In a subsequent step, we need to activate the new virtual environment.
\nmodule unload python\/3.3.6\u00a0\u00a0 # Unload the parent distribution <\/span><\/code><\/p>\ncd ~\/MyVenv
\nsource bin\/activate
\n[u0253283@dirac MyVenv]$ source bin\/activate
\n(MyVenv) [u0253283@dirac MyVenv]$<\/span><\/code><\/p>\n(MyVenv) [u0253283@dirac MyVenv]$ which python3\u00a0 # Check the distribution
\n~\/MyVenv\/bin\/python3<\/span><\/code><\/p>\n(MyVenv) [u0253283@dirac MyVenv]$ python3 --version
\nPython 3.3.6<\/span><\/code><\/p>\n
\npython3
\n>>>import numpy as np
\n>>>np.__path__
\n['\/uufs\/chpc.utah.edu\/sys\/installdir\/python\/3.3.6\/lib\/python3.3\/site-packages\/numpy']<\/span><\/code><\/p>\n>>>a = np.arange(10)
\n>>>a**3
\narray([\u00a0 0,\u00a0\u00a0 1,\u00a0\u00a0 8,\u00a0 27,\u00a0 64, 125, 216, 343, 512, 729])<\/span><\/code><\/p>\n
\nHowever, the pip executable can be easily installed in the Virtual Environment as follows:
\n(MyVenv) [u0253283@dirac ~]$ python3 -m pip install -U pip <\/span><\/code><\/p>\n\n
\n(MyVenv) [u0253283@dirac ~]$ pip install qit
\n(MyVenv) [u0253283@dirac ~]$ python3
\nPython 3.3.6 (default, Jan 20 2015, 11:39:02)
\n[GCC 4.4.7 20120313 (Red Hat 4.4.7-11)] on linux
\nType \"help\", \"copyright\", \"credits\" or \"license\" for more information.
\n>>> import qit
\n>>> qit.__path__
\n['\/uufs\/chpc.utah.edu\/common\/home\/u0253283\/MyVenv\/lib\/python3.3\/site-packages\/qit']<\/span><\/code><\/li>\n
\n# Requirements:<\/p>\n\n
module load git
\ncd ~
\ngit clone https:\/\/github.com\/sunpy\/sunpy.git sunpy_src
\ncd sunpy_src
\npython3 setup.py build
\npython3 setup.py install
\ncd ~ ; rm -rf sunpy_src <\/span><\/code><\/p>\n
\nthe user has by default access to the subdirectories within the virtual
\nenvironment.<\/p>\n# Test of the installation:
\npython3
\n>>> import sunpy
\n>>> sunpy.__path__
\n['\/uufs\/chpc.utah.edu\/common\/home\/u0253283\/MyVenv\/lib\/python3.3\/site-packages\/sunpy-0.8.dev7032-py3.3.egg\/sunpy']
\n>>> import sunpy.data
\n>>> sunpy.data.download_sample_data()
\n>>> import sunpy.data.sample
\n>>> import sunpy.map
\n>>> aia = sunpy.map.Map(sunpy.data.sample.AIA_171_IMAGE)
\n>>> aia.peek()<\/span><\/code><\/li>\n<\/ul>\n
\nWe can leave the Virtual Environment easily by invoking ‘deactivate<\/em>‘:
\n(MyVenv) [u0253283@dirac ~]$ deactivate
\n[u0253283@dirac ~]$<\/span><\/code><\/p>\n
\nWe can get rid of the Virtual Environment by deleting the directory:
\n[u0253283@dirac ~]$ rm -rf ~\/MyVenv<\/span><\/code>\t\t<\/p>\n","protected":false},"excerpt":{"rendered":"