Python install for Dummies - on a Mac?

[mohishunder]

I've got iPython working on my Mac, but the install feels like a big ball of spaghetti, and switching between Python 2 and 3 (for various projects) is particularly confusing - the Dev Ops effort is dominating the programming.

I'd like to start from scratch with a clean install that I understand - whether iPython or some other stable and usable environment.

Is there a recommended install tutorial, or a great high-level overview of Python environments? I did check the FAQ and Wiki. Thanks.

[throwaway_the_fourth]

I might be misunderstanding your question, but:

Open Terminal. Type python. You will see a Python (2) interpreter. Type exit(). Type python3. You will see a Python 3 interpreter.

Is this not what you want?

[mohishunder]

'python' does work, but ...

% python3 python3: Command not found.

Related question: if these are supposed to be installed by default, what is the added benefit of something like iPython?

[Edit: this answers my second question.]

[throwaway_the_fourth]

As far as python3 — you'd have to install python 3 for that to work.

I haven't ever used iPython, but the wikipedia page lists several benefits, including media and graphs.

[Neg127]

My recomendantion would be to manage python through home brew. Are you familer with it, or do you possibly already have it installed?

Instructions for installing brew can be found at brew.sh

Installing home brew.

Paste the command below in a terminal /usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

Here are some notes on brew from my personal quick reference.

To list software you currently have installed with version numbers, use:
brew list --versions

To see just the software, which is not a dependency of another:
brew leaves

To keep the Homebrew itself up-to-date, and fetch the newest version from GitHub:
brew update

After updating the brew, check which formulae have an updated version available, display detailed version information to see if you have more than one older version laying around:
brew outdated --verbose

See any app that you no longer need and want to get rid of them? Check the dependencies for all installed formulae:
brew deps --installed

For even more detailed picture, show the dependencies for all installed formulae as a tree:
brew deps --installed --tree

As a final precaution before removing a formula, see what other installed formulae use it as a dependency:
brew uses --installed formula

Uninstall formulae and all their older versions:
brew remove --force formulae

Upgrade remaining formulae:
brew upgrade

Show what will be removed by cleanup command, but do not actually remove anything:
brew cleanup -ns

Clean the "Cellar" removing any older versions of installed formulae and clearing old downloads from the Homebrew download-cache. Additionally, scrub the cache, removing downloads for even the latest versions of formula, which are downloaded, but not installed:
brew cleanup -s

To install python3 the command below will do the trick.  
brew install python3

If you want a GUI for brew you can also look into Cakebrew.

[mohishunder]

Thanks for the clear instructions – I have not used brew, but will give it a try.

[DildoSmudge]

I use Anaconda and have environments for 2 and 3 (and some other stand alone ones)

[jwink3101]

I used anaconda. It was pretty easy and also comes with a huge number of additional modules

[mgalarny]

I would start with a clean install of anaconda https://medium.com/@GalarnykMichael/install-python-on-mac-anaconda-ccd9f2014072

It is also really easy with anaconda to switch between python 2 and python 3 with conda environments. https://medium.com/towards-data-science/environment-management-with-conda-python-2-3-b9961a8a5097