“Attributes are additional pieces of information that describe a spatial feature in a GIS”
Attribute data are tabular data that describes the characteristic of a particular feature. The tabular data can store data in different field types namely character data, numeric and date/ time. In this module, we will learn about attributes and explore the different field types and the kind of data it stores. We will also learn how to edit the data.
Goal: Explore and edit attributes
Vector geodata consists of tables (picture a spreadsheet with its rows and columns). What we call a 'layer' is actually a table, no matter what format it is on disk. The table consists of one or more columns (aka 'fields', 'properties', 'attributes') and zero or more rows (aka 'records' or 'features'). What makes the table a vector layer is the geometry column. So, for a spatial layer, that is the minimum requirement. The geometry in the geometry field is what the GIS software draws in the map and is what we often call a 'feature'. Any other columns we call 'attributes' in the GIS world. They are also just data fields but instead of containing geometry they contain text, numbers, dates etc.
Attributes can be present in the same table as the geometry (as in a shapefile) but they often come from other tables via a 'join', where rows are matched based on a 'key' or on a spatial relationship.
Raster data also has attributes, although normally just one - the value of the cell.
Click here to download the sample data for the lesson.