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Setting up Python developer environment on Ubuntu

This document contains a description on setting up a Python developer environment on Linux Ubuntu. This document was tested on Ubuntu Trusty 14.04. If you find errors or if you find anything missing, please send in a pull request with your changes. All pull requests are well accepted.

There are many great tools that can help you writing awesome Python code. The tools that are mentioned in this documents are the once I use daily when working with Python code.

Install Python

Python 2.7 is pre-installed when you install Ubuntu but the Python shared library and the library headers are missing. Many python packages which are not written in Python depend on these things.

Before, let us install the famous build essentinal package which includes the C/C++ compilers from GNU. Open up your terminal and type in the following.

~$ sudo apt-get install build-essential

Next we install the python development package which installs the Python shared library and header files.

~$ sudo apt-get install python-dev

Pip and virtualenv

Pip is a package management system used to install and manage software packages written in Python. Many packages can be found in the Python Package Index PyPI but packages can be installed directly from Github or from local packages on your machine.

With Pip we can install external Python packages that we need in our Python projects. To name a few, these can be Flask, Django or SQLAlchemy.

~$ sudo apt-get install python-pip

We use Pip heavily when we are writing our Python projects in this course so be sure to install it properly.

Next we install Python virtualenv. This one is my favourite and I can't understand how I was able to live without it couple of years ago. Virtualenv allows you to create a virtual environment, put simply, an isolated working copy of Python which allows you to work on a specific project without worry of affecting other projects. For example, if you are working on two different projects with different dependencies you can install them into the virtualenv without installing it into the global Python installation on your machine. Brilliant. When the virtualenv is active you can use all the packages that were installed into that environment. When you are done, you remove the environment without leaving any trace of files on your hard drive.

To install virtualenv, open up your terminal and type in the following.

~$ sudo apt-get install python-virtualenv

Before you continue, take a brew moment and Google Pip and virtualenv and read more about them. They will make your life so much easier in the future. I recommend this blog post by Jamie Matthews to start with.

Let's take our environment for a spin drive

Now let's take our new environment for a spin and write a small application that prints out to the stdout the movies that are being shown in the Icelandic theatres. We use the apis.is/cinema API. Be sure to give them some follow up on their Github page. Great API that you can use in your applications.

Our application will depend on two Python packages:

  • requests: Nice package for crafting web requests.
  • termcolor: For printing out on stdout in colours.

Create a folder somewhere on your disk, I used ~/Desktop/movies. You can do the same.

~$ mkdir ~/Desktop/cinema
~$ cd ~/Desktop/cinema

In that folder we will create a Python virtualenv (under the folder .venv) for the external packages that we depend on.

~/Desktop/cinema$ virtualenv .venv
New python executable in .venv/bin/python2.7
Also creating executable in .venv/bin/python
Installing setuptools, pip...done.

Next we enable the virtualenv in our shell. Note that you are only activating the virtualenv in the shell that you are using. If you open up a new one you must enable the virtualenv for that shell as well.

~/Desktop/cinema$ source .venv/bin/activate
(.venv)~/Desktop/cinema$

Next we install the two above mentioned packages into our virtualenv. Pip packages can be install with pip install. You can also search on Pypi using pip search.

(.venv)~/Desktop/cinema$ pip install requests
Downloading/unpacking requests
  Downloading requests-2.4.1-py2.py3-none-any.whl (458kB): 458kB downloaded
Installing collected packages: requests
Successfully installed requests
Cleaning up...

(.venv)~/Desktop/cinema$ pip install termcolor
Downloading/unpacking termcolor
  Downloading termcolor-1.1.0.tar.gz
  Running setup.py (path:/Users/hlysig/Desktop/cinema/.venv/build/termcolor/setup.py) egg_info for package termcolor

Installing collected packages: termcolor
  Running setup.py install for termcolor

Successfully installed termcolor
Cleaning up...

Now open up your favourite text editor and type (or paste) the following code into file named cinema.py:

import json
import sys

import requests
from termcolor import colored


def show_running_movies():
    """
    Fetches movies that are beeing shown in Icelandic theaters and
    prints them out to stdout
    """
    # Do a get request to cinema api at api.is
    response = requests.get('http://apis.is/cinema')

    # If we don't receive a 2xx status code, we stop and print error.
    if not response.ok:
        print 'Unable to read from api, got non ok status code: {0}'\
            .format(response.status_code)
        sys.exit(1)

    # The response is on json format. We use python json module to
    # parse the json
    # and map it into a Python associated array (dictionary)
    d = json.loads(response.text)

    # We loop through the result and print it to stdout.
    for res in d.get('results'):
        print colored(res.get('title').encode('utf-8'), 'yellow')
        for showtime in res.get('showtimes'):
            print ' ', showtime.get('theater').encode('utf-8')
            for schedule in showtime.get('schedule'):
                print '  ', schedule.encode('utf-8')

if __name__ == '__main__':
    show_running_movies()

Exit your editor and run the script.

(.venv)~/Desktop/cinema$ python cinema.py
Afinn
  Sambíóin Álfabakka
   15:20 (1)
   15:20 (P)
   17:40 (1)	
   ...

If everything went well the script should print out the movies that are being shown. Nice ey?

If you are new to Python please stop and read through the code and convince yourself that it does what it is meant to do. The author of the Python language states that the language is so simple that it is almost identical to natural languages. I don't agree. But simple well written Python code can be that way, but most often in large python code base things can be quite tricky. But that is my rant. Don't take my word for it.

You should now have everything setup for writing Python code on your Linux.