Sample 24899: Draw latitude and longitude lines on a map
/*********************************************************/
/* The following program uses the Annotate Facility to */
/* draw longitude and latitude grid lines on a map of */
/* North America. You can change the intervals at which */
/* the dashed lines and solid lines are drawn by */
/* changing the values in the DINTERVL and SINTERVL */
/* macro variables, respectively. */
/* This program also uses the XSIZE and YSIZE options on */
/* the CHORO statement in PROC GMAP to specify the size */
/* of the map output. You may need to change these */
/* values depending on your output device. */
/*********************************************************/
goptions reset=all;
/* Specify the interval (in degrees) at which the dashed */
/* grid lines should be drawn. */
%let dintervl=10;
/* Specify the interval (in degrees) at which the solid */
/* grid lines should be drawn. Make sure that the value */
/* is an even multiple of &DINTERVL */
%let sintervl=20;
/* Since we want to annotate onto a map, we need to use */
/* the unprojected values from the map data set. The */
/* NAMERICA map data set contains the projected */
/* longitude, X, the projected latitude, Y, as well as */
/* the unprojected longitude, LONG, and the unprojected */
/* latitude, LAT. In order to use the unprojected values */
/* for the map, we need to drop the existing X and Y */
/* variables and rename the LONG and LAT variables to X */
/* and Y. */
data namerica(rename=(long=x lat=y));
set maps.namerica(drop=x y);
run;
/* Determine the minimum and maximum latitude and */
/* longitude values in the map data set */
proc means data=namerica noprint min max;
var y x;
output out=minmax min=miny minx max=maxy maxx;
run;
/* Create macro variables for the minimum and maximum */
/* latitude and longitude values */
data _null_;
set minmax;
/* Convert radians to degrees */
miny=miny/(atan(1)/45);
maxy=maxy/(atan(1)/45);
minx=minx/(atan(1)/45);
maxx=maxx/(atan(1)/45);
/* Assign the min and max values to macro variables */
call symput('miny',left(put(miny,4.)));
call symput('maxy',left(put(maxy,4.)));
call symput('minx',left(put(minx,4.)));
call symput('maxx',left(put(maxx,4.)));
run;
/* Create an annotate data set to draw and label the lines */
data anno;
/* Specify the length for annotate variables */
length color function text style $8;
/* The coordinate system is set to data values. */
/* The ANNO variable identifies observations from */
/* the annotate data set. */
retain xsys ysys '2' anno 1;
/* Draw the longitude lines */
do i = &minx to &maxx by 1;
/* Convert degrees to radians */
x = (atan(1)/45) * i;
y = (atan(1)/45) * &miny;
function='move';
/* Check to see if a solid line should be drawn */
if mod(i,&sintervl)=0 then do;
/* Output the location to move to */
output;
/* Increment the Y value */
y = (atan(1)/45) * (&maxy + 1);
/* Specify a solid line style */
line=1;
/* Solid line should be black */
color='black';
/* Label the line */
function='label';
/* TEXT is the value to output */
text=left(put(i,5.));
/* Position the label one half cell centered */
/* above the x,y location */
position='B';
/* Specify the font and size for the label */
style='centbi'; size=1;
output;
/* Draw the line with a size of 1.75*/
function='draw'; size=1.75;
output;
end;
/* Line should be dashed */
else if mod(i,&dintervl)=0 then do;
/* Output the location to move to */
output;
/* Increment the Y value */
y = (atan(1)/45) * (&maxy + 1);
/* Specify a dashed line style */
line=33;
/* Dashed line should be blue with a size of 1 */
color='blue'; size=1;
/* Draw the line */
function='draw';
output;
end;
end;
/* Draw the latitude lines */
do i = &miny to &maxy by 1;
/* Convert degrees to radians */
x = (atan(1)/45) * &minx;
y = (atan(1)/45) * i;
function = 'move';
/* Check to see if a solid line should be drawn */
if mod(i,&sintervl)=0 then do;
/* Output the location to move to */
output;
/* Increment the X value */
x = (atan(1)/45) * (&maxx + 1);
/* Specify a solid line style */
line=1;
/* Solid line should be black */
color='black';
/* Label the line */
function='label';
/* TEXT is the value to output */
text=trim(left(put(i,5.)));
/* Position the label one half cell right aligned */
position='<';
/* Specify the font and size for the label */
style='centbi'; size=1;
output;
/* Add more points to curve the latitude */
do j = &minx to (&maxx+1) by 1;
/* Draw the line with a size of 1.75 */
function='draw'; size=1.75;
/* Increment the X coordinate */
x = (atan(1)/45) * j;
output;
end;
end;
/* Line should be dashed */
else if mod(i,&dintervl)=0 then do;
/* Output the location to move to */
output;
/* Increment the X value */
x = (atan(1)/45) * (&maxx + 1);
/* Specify a dashed line style */
line=33;
/* Dashed line should be blue with a size of 1 */
color='blue'; size=1;
/* Add more points to curve the latitude */
do j = &minx to (&maxx+1) by 1;
/* Draw the line */
function='draw';
/* Increment the X value */
x = (atan(1)/45) * j;
output;
end;
end;
end;
run;
/* Since the annotation will extend beyond the map coordinates, */
/* create dummy points for the 4 outer corners of the map. */
/* We need to include the identification variable, ID for the */
/* NAMERICA map data set, in the CORNERS data set. Select */
/* values that will not correspond to values in the map data */
/* set. */
data corners;
/* Convert degrees to radians and adjust the coordinates */
x=(atan(1)/45) * (&minx-1);
y=(atan(1)/45) * (&miny-1);
id=-1; output;
x=(atan(1)/45) * (&minx-1);
y=(atan(1)/45) * (&maxy+1);
id=-2; output;
x=(atan(1)/45) * (&maxx+1);
y=(atan(1)/45) * (&maxy+1);
id=-3; output;
x=(atan(1)/45) * (&maxx+1);
y=(atan(1)/45) * (&miny-1);
id=-4; output;
run;
/* Combine all of the data sets together for projection */
data all;
set corners namerica anno ;
run;
/* Create a new data set, ALLPROJ, that contains the projected values */
/* specify the gnomonic projection and center the projection using the */
/* polelong and polelat options. The DUPOK option tells GPROJECT not */
/* to delete observations with duplicate X and Y values. */
/* If you want the map to reflect the curvature of the map, remove */
/* the PROJECT=, POLELONG=, POLELAT=, and DEGREE options. */
proc gproject data=all out=allproj project=gnomon polelong=0 polelat=45 degree dupok;
id id;
run;
/* Separate the projected data back into an annotate data set and a */
/* map data set. */
data namerica anno;
set allproj;
/* The ANNO variable value of 1 identifies observations from the */
/* annotate data set. */
if anno=1 then output anno;
else output namerica;
run;
pattern v=ms;
title 'Map of North America with grid lines';
/* Generate a map of North America with longitude and latitude grid lines */
proc gmap map=namerica data=namerica all;
id id;
/* Outline map areas in gray, suppress the legend, treat the ID variable */
/* as a discrete variable, specify the ANNO annotate data set, and use */
/* the XSIZE and YSIZE options to specify the size of the map output. */
choro id / coutline=gray nolegend discrete
anno=anno xsize=9 in ysize=6.75 in;
run;
quit;
This sample program draws longitude and latitude grid lines on a map of North America.
| Type: | Sample |
| Topic: | SAS Reference ==> Procedures ==> GMAP
Query and Reporting ==> Creating Reports ==> Graphical ==> Graph Types ==> Maps ==> Special Maps
|
| Date Modified: | 2007-11-13 14:52:18 |
| Date Created: | 2004-11-11 11:07:57 |
Operating System and Release Information
| SAS System | SAS/GRAPH | All | n/a | n/a |
