The input map data set must be a SAS
data set and contain these variables:
-
a numeric variable named X that
contains the horizontal coordinates of the map boundary points.
-
a numeric variable named Y that
contains the vertical coordinates of the map boundary points.
-
one or more identification variables
that uniquely identify the unit areas in the map. These variables
are listed in the ID statement.
It can also contain
the following:
-
one or more variables that identify
groups of unit areas (for BY-group processing)
-
the variable SEGMENT, which distinguishes
nonconterminous segments of the unit areas.
Any other variables
in the input map data set do not affect the GREDUCE procedure.
