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Homebrew and venv

1.8. Homebrew and venv#

last update: Feb 07, 2024

What is a package manager?

A package manager or package-management system is a collection of software tools that automates the process of installing, upgrading, configuring, and removing computer programs for a computer in a consistent manner. - wikipedia

There are various package managers.

For OS level,

  • Windows: vcpkg

  • Mac: Homebrew

  • Ubuntu: apt

For application level,

  • PHP: composer

  • JavaScript(node): npm, Yarn

  • Ruby: gem

  • Java: Maven, Gradle

  • Python: pip, conda

  • R: conda, CRAN

In this page, we install homebrew and make a venv to manage python packages.

1.8.1. Homebrew#

Homebrew is　a missing package manager for macOS (or Linux). To install it, input next code in the Terminal (you should check the newest code here);

/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"

you will get next output:

==> Next steps:
- Run these two commands in your terminal to add Homebrew to your PATH:
    echo 'eval "$(/opt/homebrew/bin/brew shellenv)"' >> /Users/kensuke/.zprofile
    eval "$(/opt/homebrew/bin/brew shellenv)"
- Run brew help to get started
- Further documentation:
    https://docs.brew.sh

So input next to add Homebrew to your PATH (change Username below):

echo 'eval "$(/opt/homebrew/bin/brew shellenv)"' >> /Users/Username/.zprofile
eval "$(/opt/homebrew/bin/brew shellenv)"

Let’s check whether you succeeded!

brew --version

if you get: Homebrew x.x.x, you succeeded.

1.8.2. Venv#

To make a virtual environment for python, venv is the easiest tool! Although there are pyenv or anaconda for python, they are not necessary for beginners. Let’s make a venv. Making and deleting a venv are really easy. Let’s make a test venv in your home directory.

python3 -m venv ~/test

then activate the venv:

source test/bin/activate

or

. test/bin/activate

Now your venv is activated. You can see the name of venv on the left side of your user name in the terminal like (test) Username@MacBook-Pro ~ %. Let’s check the version of python:

python -V

and you get Python 3.x.x.

Now you made a new venv and activated it, but actually there is almost nothing in the venv. pip list --format=freeze shows the packages in your venv and there is no output for now. Before installing something, you might have to upgrade pip, which is a python package manager(change Username below):

/Users/Username/test/bin/python3 -m pip install --upgrade pip

then let’s install a package (here numpy)!

pip install numpy

and let’s check:

pip list --format=freeze

and you get numpy==x.xx.x.

If you want to use python as a beginner, you should install matplotlib, pandas, and jupyter-lab;

pip install matplotlib
pip install jupyterlab

Matplotlib is a library for visualization, pandas for data analysis and manipulation, and jupyter-lab for web-based user interface for running python code. Scipy, which is for scientific computing, is also a useful package for some people. Now you can see many packages in your test venv; try pip list --format=freeze, though you installed apparently just 4 or 5 packages. Actually, you installed many packages with jupyter-lab. To deactivate the venv, just input: deactivate in the terminal. To activate again, input; source test/bin/activate.

Warning

If you want to delete the venv, remove it with:

rm -rf ~/test

in the terminal.

1.8.3. Let’s use jupyter-lab!#

You installed jupyter-lab, so let’s try to use it !!

jupyter-lab

Your default browser will show up and open jupyter-lab.

To deactivate juypter-lab (not venv) in the Terminal; Control + C and you will be asked whether to quit, then enter y[yes]. For more details, see this page.

Note

  • Renaming venv

  • Renaming the parent directories of venv

  • Changing the location of venv
    are not recommended.

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