Geocoding Address Data

Geocoding is a process by which addresses are given coordinate locations, thus allowing them to be manipulated in a GIS. In other words, geocoding transforms tabular data into spatial data. Reverse Geocoding is when you begin with a set of geolocated points (coordinates) and use a tool to get the street addresses of each point. This page will guide you through geocoding using the MMQGIS plugin.

1 From the workshop data folder, add libraries.csv to your QGIS project. This is a list of libraries in Vancouver, also downloaded from Vancouver’s Open Data Portal. Because it is tabular data (in the form of a .csv, or comma separated value table) and not a spatial layer, nothing will show up on your map. Take a look at the attributes of this table. You’ll see there are street address as well as city and country attributes. We’ll use these to geocode this dataset.

2 Install MMQGIS plugin from the Plugins Manager. You’ll see it adds an entire menu to the top of your screen. Take a look at different options. Choose Geocode CSV with Web Service.

3 In the geocoding window that opens, chose the libraries.csv file as your input and leave the outputs as temporary files. The address, city, and country properties will likely auto-populate since the column names directly reference the input fields. Sometimes you do have to manually match the properties.

Change the web service to Open Street Map / Nominatim. Hit apply. There are 21 rows in the library dataset so 21 points should be geocoded. The output csv that indicates what wasn’t matched should be empty.

4 If you want to save your geocoded output as a spatial data layer, simply save the temporary file as a permanent layer. To do this, right-click the layer and Export it, giving it a name and appropriate storage location.

Resources

See another GeoCoding, another plugin specific to finding addresses or reverse geocoding
See another resource on Geocoding plugins
You don’t need to geocode in a GIS! If you aren’t using a GIS for any other portion of your project, consider using an online geocoder like BC Address Geocoder or geocodio, or explore more free and paid options here