Producing Maps

SAS/GRAPH uses the GMAP procedure to produce two- and three-dimensional maps that can show an area or represent values of response variables for subareas. SAS/GRAPH includes data sets to produce geographic maps. In addition, you can create your own map data sets.

Overview of Mapping

Block Maps

Choropleth Maps

Prism Maps

Surface Maps

Procedures for Handling Map Data

Overview of Mapping

The GMAP procedure produces maps that display values or attributes related to areas on the map. The procedure can produce the following types of maps:

The procedure can summarize data that vary by physical area, show trends and variations of data between geographic areas, and highlight regional differences or extremes.

SAS/GRAPH also provides several utility procedures for processing and handling map data. For example, you can convert map coordinates from spherical (longitude and latitude) to a flat plane. For more information, see Procedures for Handling Map Data.

Options for controlling the appearance of maps include specifying the boundary density and controlling numeric ranges and categories. You can specify patterns, legends, and ODS styles. You can also use the SAS/GRAPH annotation feature to annotate graphs.

For more information and procedure syntax, see GMAP Procedure.

Block Maps

Block maps are three-dimensional maps that represent data values as blocks of varying height rising from the middle of the map areas.

See GMAP Procedure for a complete description.

Choropleth Maps

Choropleth maps are two-dimensional maps that display data values by filling map areas with combinations of patterns and color that represent the data values.

See GMAP Procedure for a complete description.

Prism Maps

Prism maps are three-dimensional maps that display data by raising the map areas and filling them with combinations of patterns and colors.

See GMAP Procedure for a complete description.

Surface Maps

Surface maps are three-dimensional maps that represent data values as spikes of varying heights.

See GMAP Procedure for a complete description.

Procedures for Handling Map Data

SAS/GRAPH provides several utility procedures for handling map data.

Procedure	Description
GEOCODE	Adds geographic coordinates to data sets that contain information such as mailing addresses. The coordinates typically represent the center of a ZIP code, a city, an address, or any geographic region. After geocoding, the coordinates can be used to display a point on a map or to calculate distances. Geocoding also enables you to add attributes values such as census blocks to an address. You can also use geocoding to associate ranges of IP addresses with locations.
GINSIDE	Compares a data set of X and Y coordinates to a map data set containing map polygons. The procedure determines whether the X and Y coordinates for each point fall inside of or outside of the map polygons. The results can be used to annotate onto a map with the GMAP procedure.
GPROJECT	Enables you to choose how geographic maps are projected. This is particularly important for large areas. Producing a map of any large area on the Earth involves distorting some areas in the process of projecting the spherical surface of the Earth onto a flat plane. You can use the procedure to select the projection method that least distorts your map.
GREDUCE	Enables you to reduce the number of points in the data set. This is useful for large maps, where the amount of data can be prohibitively expensive in terms of computing resources or time to process.
GREMOVE	Enables you to remove boundary lines within a map. For example, if your map shows sales regions, you might want to remove state borders and show only the sales regions. The results of this procedure are used as the input map data set for the GMAP procedure.
MAPIMPORT	Converts Esri shapefiles into SAS map data sets.