Geo Information Minor Python course

Dear Geo Information Minor student,

Welcome to the Vrije Universiteit Python course. In this course we'll take a small dive into the Python programming language. We'll cover some basic programming concepts and briefly delve into data acquisition by using API's.

From previous iterations we've distilled that learning the basics isn't the challenge (anymore) due to the abundance of open online courses and interactive online tutorials. Rather, the question is: how do I craft useful scripts that solve real-world problems?

Hence, we'll show you how to apply your knowledge to the challenges you'd like to address day-to-day activities. Along the way, we'll show you how to solve common Python-related problems, give you tips-and-tricks about finding help and expanding Python's capabilities with external modules.

This course is extremely hands-on: we don't have slides or extensive lecture notes; we'll only show and execute Python code. We think we can get away with this approach only because you'll have done the bulk of the learning by the time you join us on Monday morning.

Curious? Read on!

Course overview

• Introduction to Python
• Introduction to debugging
• Getting help: introduction to StackOverflow and online documentation
• Introduction to API access using the requests module
• Accessing the twitter API using the twython module

Methodology and programme

This course consists of a self-learning part and two hands-on workshops. Each workshop lasts a full day. Interactive lectures are planned for the mornings while the afternoons are filled with supervised practical assignments.

The program is as follows:

• self-study: Python course on Codeacademy
• workshop I:
  • morning: interactive recap of Codeacademy material, introduction to API's and requests
  • afternoon: practical assignment - using the Luchtmeetnet API, with the requests module
• workshop II:
  • morning: recap of workshop I, introduction to Twitter API and twython
  • afternoon: practical assignment - using the Twitter API, with the twython module

Each interactive session + practical assignment pair is accompanied by a short manual and some Python scripts, see the lecture materials section below for more information.

Self-study: codeacademy.com

To maximize the time available for the hands-on lectures and exercises we kindly ask you to complete a number of Codeacademy Python lessons in advance.

codeacademy.com is an online learning platform that offers programming courses in a wide range of languages. You learn to program by typing and executing Python commands directly in your browser.

Register for Codeacademy as follows:

1. go to https://www.codecademy.com/ and register
2. log in and navigate to the Python course
3. click Start

Please complete the following exercises before coming to class on the 19th of September.

• Unit 1 - Lesson: Python Syntax
• Unit 2 - Lesson: Strings & Console Output
• Unit 3 - Lesson: Conditionals & Control Flow
• Unit 4 - Lesson: Functions
• Unit 5 - Lesson: Python Lists and Dictionaries
• Unit 7 - Lesson: List and functions
• Unit 8 - Lesson: Loops
• (optional) Unit 10 - Lesson: Advanced Topics in Python
• Unit 12 - Lesson: File Input and Output

Practice makes perfect: feel free to complete any of the other lessons and or exercises after you've gone through this list.

Lecture materials

The lecture notes are split in three chapters. Each chapter contains a short manual and one or more Python scripts.

• Chapter 1 - recap - recap of the Codeacademy material you studied by yourself.
• Chapter 2 - Luchtmeetnet API - describes the Amsterdam API assignment + hints/tips/tricks about using an API.
• Chapter 3 - Twitter API - describes the Twitter API assignment + hints/tips/tricks about using the Twitter API.

You can download the accompanying Python scripts as follows:

1. scroll to the top of this page
2. click on the green button labelled Clone or download
3. click on Download ZIP
4. Unzip the file you downloaded and load the .py scripts contained in one of the folders in your favourite editor.

Installing Python (Windows)

You'll need to install Python and a number of external modules on your machine to run the example scripts and perform the exercises. To make it easier we will use a Python distribution that already comes with a large number of modules that are useful for scientific computing, called Anaconda. Anaconda also comes with a module manager called Conda, which we will use to install a few modules.

It is up to you if you download the Python 3.6 or Python 2.7 version. There are some differences between them, but they won't be very noticeable in the exercises we will be doing. For a long time Python 2 stayed the most used version in the GIS world. At the moment we are seeing more and more applications make the shift to Python 3. ArcGIS Pro and QGIS 3, for example, both use Python 3, while ArcGIS Desktop still uses Python 2.

You can install Anaconda and the needed modules as follows:

• Download and install Anaconda -> Download Anaconda and double click it. You can accept the default choices. You can skip the installation of Visual Studio Code. This is a text editor made for coding, and while it is a really good application, we will not use it in this course.

• Install the geopandas module: open a Anaconda prompt (Start Menu -> Anaconda -> Anaconda Prompt) in administrator mode (right click -> More -> Run as administrator) and enter the following command:

  conda install geopandas

  press Enter to execute it.

• Install the twython module: open a Anaconda prompt (Start Menu -> Anaconda -> Anaconda Prompt) and enter the following command:

  conda install twython

  press Enter to execute it.

• If you ever want to install other modules just Google conda *module name* and look for the result (with Anaconda Cloud in the title) with the latest version available for your platform. Copy the text under To install this package with conda run one of the following: and enter this command in the Anaconda prompt.

Test if everything works:

• start the Python editor Spyder (Start Menu -> Anaconda -> Spyder) NOTE: If spyder does not start, reinstall anaconda and skip the step to install geopandas. In the exercises skip the steps which involve geopandas.
• copy/paste the following code into the newly opened editor

Python 3:

import geopandas
import twython

print('Everything works!')

Python 2:

import geopandas
import twython

print 'Everything works!'

• save the file: File -> Save
• run the code: Run -> Run
• do you see Everything works! in the output screen? Great, you're all set!
• do you see something else? Too bad, something's wrong. Please copy/paste the output in the issue tracker (see below for instructions) and we'll try to assist you.

Getting help

Please use the issue tracker to post questions about the lecture notes, examples, exercises and Python in general or in case you're having difficulties installing Python.

1. scroll to the top of this page and click on Issues
2. click on the green button labelled New issue
3. enter a descriptive Title and a describe your issue/question in the Comment textbox.

Note: you need a GitHub account to post an issue.

We encourage you to use the issue tracker as it

• the act of verbalizing your problem often times leads you to a solution
• is a nice collaborative learning mechanism: seeing other people's questions is a sure way to learn something new and unexpected
• saves you a lot of time in case someone else has posted your question already
• saves us a lot of time since we don't have to answer each question separately (through mail)

Not convinced? Feel free to send us an email.

The team

• Eduardo Dias
• Simeon Nedkov
• Chris Lucas
• Maurice de Kleijn