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The GREMOVE Procedure |
The GREMOVE procedure processes the input map data set to remove internal boundaries and creates a new map data set. The PROC GREMOVE statement identifies the input and output map data sets. The ID statement identifies the variable or variables in the input map data set that define the current unit areas. The BY statement identifies the variable or variables in the input map data set that define the new unit areas.
About the Input Map Data Set |
The input map data set must be in map data set format (see About Map Data Sets) and it must contain these variables:
About the Output Map Data Set |
The output map data set may contain missing X, Y coordinates to construct any polygons that have enclosed boundaries (like lakes or combined regions that have one or more hollow interior regions).
All current unit areas with common BY-variable value(s) are combined into a single unit area in the output map data set. The new unit area contains
About Unmatched Area Boundaries |
For example, if you have a map data set named APPROX in which the horizontal and vertical coordinate values for interior boundaries of unit areas are exactly equal only to three decimal places, this DATA step creates a new map data set, EXACT, that is better suited for use with the GREMOVE procedure:
data exact; set approx; if x ne . then x=round(x,.001); if y ne . then y=round(y,.001); run;
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