Examples of Common Spatial Data Tasks

The following examples illustrate common tasks for preparing spatial data. Each example builds upon the preceding examples. Use the DATA step and data set provided in Importing Your Spatial Data to import a data set containing spatial data for the counties of North Carolina and South Carolina. Use this map to perform the actions described in the rest of the chapter.

Importing Your Spatial Data

Suppose you are given the task to determine the level of change in the county populations for the states of North Carolina and South Carolina. SAS/GIS software provides you with the information that is collected in the MAPS.USAAC sample attribute data set. For each U.S. county, this data set has an observation that includes the following variables:

STATE

The FIPS (Federal Information Processing Standards) code for the state. See “Using FIPS Codes and Province Codes” in SAS/GRAPH: Reference for more information about FIPS codes.

COUNTY

The FIPS code for the county.

CHANGE

The level of change in the county population.

In order to analyze the data in MAPS.USAAC, you need a map with corresponding state and county boundaries and compatible identifier values. The MAPS.COUNTY map data set that is supplied with SAS/GRAPH software has coordinates for U.S. state and county boundaries and also uses FIPS codes to identify states and counties.

To extract map data that contains only the required states, submit the following program in the Program Editor window:

data work.ncsc;
   set maps.county;
   where state in (37 45);  /* FIPS codes for NC and SC */
run;

To import the spatial data, open the GIS Spatial Data Importing window with the following selections from the GIS Map window's menu bar: File

Import

Specify the following information in the appropriate fields of the GIS Spatial Data Importing window.

Import Type

SASGRAPH

SAS/GRAPH data set

WORK.NCSC

ID Vars

STATE and COUNTY

Map Entries:

Library	SASUSER
Catalog	NCSC
Name	NCSC
Action	Create

Spatial Data Sets:

Library	SASUSER
Name	NCSC
Action	Create

The following display contains an example of the GIS Spatial Data Importing window with the information correctly entered in the fields.

SAS/GIS Spatial Data Importing Window

After entering these values, select Import to begin importing the spatial data.

When you receive the message

Import complete. Close this window to display
                     the map

select Close to close the GIS Spatial Data Importing window. The imported map is now displayed in the GIS Map window, as shown in the following display.

Initial Display of Imported SAS/GRAPH Map

Note: See Importing Spatial Data for more information about importing spatial data from other formats.