The LMEC has a new tutorial available from their guides and documentation database, Cartinal. This tutorial is geared towards beginners just getting started using free tools to manipulate open data with free GIS software like QGIS.
In this activity, we explain how to find public transit data from the City of Boston’s Open Data portal. After we download subway lines, we open them up in QGIS only to find that all of the lines are symbolized exactly the same. What we really want is each line to be symbolized with the color that line segment represents in real life.
QGIS, and other mapping tools, allow users to pull values from datasets, whether those values are categorical, numerical, and so on, and use those values to inform symbolization across the map. In this exercise, we walk through how to symbolize by category, as each line segment is classified with a subway line type (“green”, “red”, “orange”, etc).
We learn how to use QGIS’s symbology menu interfaces. This online tutorial is part of a larger series of available tutorials accessible via Cartinal, geared towards promoting spatial data literacy skills. On Cartinal, users with any skill level can learn how to find and use geospatial data. We also offer one-on-one data reference services – this free service is something to take advantage of, and you can learn more on our Geospatial Research Services homepage.
You’ll never hit a paywall or be asked to subscribe to read our free articles. No matter who you are, our articles are free to read—in class, at home, on the train, or wherever you like. In fact, you can even reuse them under a Creative Commons CC BY-ND 2.0 license.