Beginner's Tutorial to GRASS GIS in Python

Introduction & Purpose

Throughout my brief years of study at Carleton University in the Geomatics discipline, I have noticed a shift towards a more ‘user-friendly’ focus in developing GIS tools. A great example of this initiative is the recent updates done to GRASS GIS with GRASS GIS83 improving the user GUI exceptionally with a single panel housing all the tools rather than many separate windows.

This apparent shift away from the traditional coding roots of GIS to a GUI dominant interface comes with upsides, downsides as well as an entirely new range of audience members. The focus of this tutorial is to explore the simple use of Python scripts written in Python 83 (8.3.10) using an open source IDE, in GRASS GIS83 using the pre-installed grass.script package in GRASS. The tutorial will consist of a few simple analyses using data from a few sources such as Open Ottawa and Ontario Geohub to demonstrate the capabilities of using GRASS with script rather than individual tools and the time it saves a user, especially when completing repetitive tasks.

From my personal experience the hardest part to kick-start your GIS coding experience is finding the resources and knowing where to start. This tutorial aims to fill the gaps in knowledge of a beginner GIS user looking to use code in GIS through a user friendly method available in GRASS. Therefore, the audience to this tutorial is marketed at beginner users that know the basic working principles of GIS, and are looking for a taste of scripting in there analysis process.

Software & Data

There are a few software downloads and installations required to follow along, all of which are open source and free to use!

The first piece of software that is required for this tutorial is an Integrated Development Environment (IDE) that provides intuitive feedback to our syntax when writing python code. I highly recommend the Spyder IDE ([1]) as it comes equipped with a few useful tools to beginners such as a syntax dictionary/troubleshooter as well as different panels for viewing plots and other outputs. This can be particularly useful when doing higher level analysis to data that is associated with a location, such as Census data. With the plot tab you can view any graphs created or plotted, as well as any mapping products created or visualized within the IDE, but for the purpose of this tutorial we are strictly making use of GRASS GIS to exemplify the 'foundation' GIS finds in coding.