Details of SAS/GIS Spatial Databases

Composites

For most operations that involve the spatial database, you refer to composites of the spatial data variables rather than directly to the variables in the spatial data sets. A composite consists of the following elements:

a variable association that identifies which variable or variables in the spatial database comprise the association. The variable association can specify a single variable, a pair of variables that define a bilateral (left-right) association, or two pairs of variables that define the start and end of a directional (from-to) bilateral association.
a class attribute that identifies the role of the composite in the spatial database.

For example, if the chains data set has a variable that is named FEANAME that contains feature names, then you can create a composite for the FEANAME variable that assigns the class attribute NAME to indicate that the composite represents feature names. If the chains data set has COUNTYL and COUNTYR variables that contain the codes for the counties on the left and right sides of the chains, then you can create a composite that is named COUNTY. The composite identifies the bilateral relationship between these two variables and assigns the class attribute AREA to indicate that the composite defines county areas in the spatial data.

Composites are created and modified using the COMPOSITE statement in the GIS procedure. Composite definitions are stored in the spatial entry.

See COMPOSITE Statement for more information about using the GIS procedure to create or modify composites.

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