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Python Installation Instructions

Python is the second programming language you will use in this course.

Note: We do not install Python using the installer from the python.org website in this course. If you have one installed, you should uninstall it before installing this version of python.

Currently the curriclum for this course is compatible with Python 3.9.

Installing pyenv

The first thing you need is to install the Python version manager (pyenv). This is similar to the nvm tool you used to install Node.JS, except it controls what versions of python you use on your system.

To install pyenv we use the pyenv-installer.

From the installation instructions on the pyenv-installer website, it says to run the following command:

curl https://pyenv.run | bash

Unlike nvm, pyenv does not automatically add it's startup lines to your shell startup file.

The files that you have to change will depend on which shell you are running (you can check which shell you have by running echo $SHELL). Follow the instructions to update the startup files associated with the shell that you are running.

If your shell is zsh

  1. Open your .zshrc with the following command
code ~/.zshrc
  1. Add the following lines.
export PYENV_ROOT="$HOME/.pyenv"
export PATH="$PYENV_ROOT/bin:$PATH"
eval "$(pyenv init -)"
eval "$(pyenv init --path)"

If your shell is bash

  1. Open your .bashrc with the following command
code ~/.bashrc
  1. Add the following lines.
export PYENV_ROOT="$HOME/.pyenv"
export PATH="$PYENV_ROOT/bin:$PATH"
eval "$(pyenv init -)"
eval "$(pyenv init --path)"

To get your startup file to execute, restart your terminal.

Installing dependencies on Windows and Ubuntu

If you use macOS you can skip this step.

For Windows and Ubuntu users you will need to install some extra dependencies for python. (See here for more information about the prerequisites: pyenv Prerequities)

First, run this command to update your apt repositories:

sudo apt update

Then, run this command to install the packages listed on the pyenv.

sudo apt-get install -y build-essential libssl-dev zlib1g-dev libbz2-dev \
libreadline-dev libsqlite3-dev wget curl llvm libncurses5-dev libncursesw5-dev \
xz-utils tk-dev libffi-dev liblzma-dev python3-openssl git

Apple Silicon ONLY: Install openssl and readline

If you are using an M1 (silicon) mac, you need to install homebrew ARM versions of openssl and readline. All other users can skip this step.

brew install openssl readline

Installing python itself

Now, you are ready to install python. You will be installing Python version 3.9.4.

Run this command to install python (you'll notice pyenv makes you put in the exact version instead of being able to just say 3.9 or 3).

pyenv install 3.9.4

After some time, this should complete without any errors. It could take a while since you are compiling python from source code.

Once this is finished, you also need to tell pyenv that this is our default version of python using this command:

pyenv global 3.9.4

Ensure that these changes take effect by closing your terminal and opening a new one. Then, verify your python is the correct version by typing:

python --version
python3 --version

Both of these commands should show 3.9.4.

Pipenv

Another piece of software you will use in class is Pipenv.

pip install pipenv

After you have installed pipenv, add this line to your shell startup file (either your .bashrc or your .zshrc) somewhere after the eval "$(pyenv init --path)":

export PIPENV_VENV_IN_PROJECT=1

Congratulations! If you've completed all these steps you are ready to code in Python!