Files for PyLadies Intro to Python 1: Setting up development environment

2013-10-09-NYCPyLadies-Workshop.md

Getting Started with Python

NYC PyLadies

RSVP at the event page

Agenda for the evening:

• (Few mins) Introductions around the group and possibly breaking into smaller groups, of 6-8 each.
• (15-20mins) Attendees will install python (see links below in download links file)
• (Intermission) Short demonstration of using virtual env and installing packages with a few commands
• (5-10 mins) Discussion of python 2 vs 3; why it's important to be organized with virtualenv
• (Assuming there is 30 mins left over) Try the 2 exercises in the gist file. If not enough time it'll be a "take home" exercise.

===

Files in this gist

• Download links for python
• Shell script for installing virtualenv
• Exercises

Download_Links.md

Python Interpreter

You have several options for getting a version of python. You'll find that everyone and their mother has an opinion on best practices for installing python. However, for the sake of this workshop we will simplify the options to two: (1) the barebones version from python.org where you can install your own python packages, and (2) the all in one package made available by Continuum Analytics. There are also other ways to install python depending on your operating system that you may hear of including brew, apt-get and so on (see the notes section below).

###Python

Option 1, cleanest install The current production versions are Python 2.7.5 and Python 3.3.2. For barebones python installation, go to http://python.org/download/ and download the source file.

Option 2, one step process If you would like to use Python for scientific computing, you may wish to consider Anaconda. The fine print says you'll need to install conda to have Python 3.3.2.

Option 3 Vagrant set up - we're in the process of creating a set up file so that all you have to do is type in vagrant up

Having python interpreter lets you compile the python code into something that your machine can run. It is necessary for any files with the *.py extension!

Python 2 vs Python 3 We're going to suggest that you go with python2 for now because it's the most commonly used, but refer to this guide for the differences between the two.

• Python 3 wall of superpowers - see which packages have been ported to python3

###Development tools

We're introducing here a couple of commonly used tools for development workflow: (1) package manager, making it easy to install and uninstall packages and (2) virtual environments to make it easier to work on more than one project at a time without introducing conflicts in their dependencies.

Note on a mac, you would install pip with sudo easy_install pip and then install virtualenv with pip install virtualenv, virtualenvwrapper

• Python Package Index - it is a manager that helps you keep track of python packages.
• VirtualEnv - virtualenv is a tool to create isolated Python environments
• VirtualEnvWrapper a set of extensions for creating and deleting virtual environments and otherwise managing your development workflow, making it easier to work on more than one project at a time without introducing conflicts in their dependencies.

NOTE

Mac OSX users may need to install the command line tools to use certain packages (free developer account required). You may also prefer using macbrew. Some people use something called macports, though be aware that it does not work well with macbrew together.

Debian based linux users can use apt-get for installing pip.

##FAQ

*Doesn't nix systems come defult with Python?

Which versions of Python are available will differ based on the package manager as well as the OS version. For example, Ubuntu 12.04 only goes up to 3.2 without adding an additional package archive (called deadsnakes). On 12.10 and newer, it may be listed as python3 and not python3.3.

I've seen people use apt-get for installations before, couldn't I use that?

Debian-based linux distribusions use aptitude (apt-get). Others (e.g., RedHat, Fedora, CentOS) use yum. People often report having issues after installing python via homebrew or macports, so the general recommendation is to install directly from python.org

Where can I learn more about python version 2 and 3?

There was a talk on this topic earlier this year by Julian Berman, on The Ups and Downs of Migrating to Python 3: A Pragmatic Approach. You can look in the comments section for slides to his talk.

Exercises.md

Exercises for Intro to Python 1: Setting up your development environment

Try these exercises to test your understanding of python installation and working from the command line. Here are some examples for reference.

# Checking Python version 
$ python --version

# Checking path to Python interpreter
$ which python

# Starting a virtual environment. 
# Creating a virtual environment will automatically drop you into it.
$ mkvirtualenv yourvirtualPython2

# Closing virtual environment 
(yourvirtualPython2)$ deactivate

# Installing a virtualenv with Python3 
$ mkvirtualenv -p 'which python3' yourvirtualPython3

# List of virtual environments 
$ workon

# Activating a virtual environment
$ workon yourvirtualPython2

# Deleting a virtual enviroment
$ rm -rf yourvirtualPython2

# Saving list of packages into a file 
$ pip freeze > requirements.txt

# previewing a text file
$ cat requirements.txt

Exercise 1

Create a virtual environment named TheHolyGrail with Python3

• Install these packages Flask, sqlalchemy, flask-sqlalchemy
• Work on TheHolyGrail
• Save the list of installed packages into a file named 'requirements.txt'
• Exit the virtual environment

Exercise 2

Create a virtual environment named KungFu

• Install these packages Python 2, pandas
• Work on KungFu
• Save the list of installed packages into a file named 'requirements.txt'
• Exit the virtual environment

To preview the requirements file from the command line, you can type in the bash command cat requirements.txt

python_setup.sh

#If you're on Mac OSX, install pip with
sudu easy_install pip

# Install virtual environment with this line. The wrapper makes it easier to use.
pip install virtualenv virtualenvwrapper

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