EXAMPLE 9  Determine Customers Within Circular Radius

Purpose: Demonstrate how to use SAS/GRAPH PROC GINSIDE to determine whether customers are in a circular sales area of a given radius.

This example is short and sweet, really just a case of re-using techniques described in detail in two previous examples. This demonstrates that once you learn a “trick” you can apply it in other ways.

First, I get the longitude and latitude (in degrees) of the approximate center of my sales region and store that in a SAS data set. In this example I am grabbing the centroid of the ZIP code 27513 from the sashelp.zipcode data set, but you could get a center longitude and latitude any way that is convenient for you.

proc sql;

 create table sales_region as

 select zip, city, x*-1 as long, y as lat

 from sashelp.zipcode

 where (zip eq 27513);

quit; run;

Then create a data set containing the X and Y coordinates of a circle that has an n mile radius from that center point. This technique is described in more detail in Example 24, “Plotting Coverage Areas on a Map.”

%let radius_miles=40;

data sales_region; set sales_region;

  retain xsys ysys '2' anno_flag 2 when 'a';

  length text function $8 style color $20 text $25;

  region_id=999999;

  x=atan(1)/45 * long;

  y=atan(1)/45 * lat;

  d2r=3.1415926/180;

  r=3958.739565;

  xcen=long;

  ycen=lat;

  do degree=0 to 360 by 5;

     if degree=0 then do;

        function='poly';

        style='empty';

        line=1;

        end;

     else do;

        function='polycont';

        color=”&inside_color”;

        end;

     y=arsin(cos(degree*d2r)*sin(&radius_miles/R)*cos(ycen*d2r)+cos(&radius_miles/R)*sin(ycen*d2r))/d2r;

     x=xcen+arsin(sin(degree*d2r)*sin(&radius_miles/R)/cos(y*d2r))/d2r;

     x=atan(1)/45*x;

     y=atan(1)/45*y;

     output;

  end;

run;

The rest of the code is the same as Example 8, “Determine Customers Within Map Borthders,” and here is the resulting map: