NAME

       plmap - Plot continental outline or shapefile data in world coordinates

SYNOPSIS

       plmap(mapform, name, minx, maxx, miny, maxy)

DESCRIPTION

       Plots  continental  outlines  or  shapefile data in world coordinates. A demonstration of how to use this
       function to create different projections can be found in examples/c/x19c. PLplot is provided  with  basic
       coastal  outlines  and  USA  state borders. To use the map functionality PLplot must be compiled with the
       shapelib library. Shapefiles have become a popular standard for geographical data and data in this format
       can be easily found from a number of online sources. Shapefile data is actually provided as three or more
       files with the same filename, but different extensions. The .shp and .shx files are required for plotting
       Shapefile data with PLplot.

       PLplot currently supports the point, multipoint, polyline and polygon objects within shapefiles.  However
       holes in polygons are not supported. When plmap is used the type of object is derived from the shapefile,
       if  you  wish  to override the type then use one of the other plmap variants. The built in maps have line
       data only.

       Redacted form: plmap(mapform, name, minx, maxx, miny, maxy)

       This function is used in example 19.

ARGUMENTS

       mapform (PLMAPFORM_callback(3plplot), input)
              A user supplied function to transform the original  map  data  coordinates  to  a  new  coordinate
              system. The PLplot-supplied map data is provided as latitudes and longitudes; other Shapefile data
              may  be  provided  in other coordinate systems as can be found in their .prj plain text files. For
              example, by using this transform we can change from a longitude, latitude coordinate  to  a  polar
              stereographic  projection.  Initially,  x[0]..[n-1] are the original x coordinates (longitudes for
              the PLplot-supplied data) and y[0]..y[n-1] are the corresponding y coordinates (latitudes for  the
              PLplot  supplied  data).   After  the  call  to  mapform(),  x[] and y[] should be replaced by the
              corresponding plot coordinates. If no transform is desired, mapform can be replaced by NULL.

       name (PLCHAR_VECTOR(3plplot), input)
              An ascii character string specifying the type of map plotted. This is either  one  of  the  PLplot
              built-in  maps  or  the file name of a set of Shapefile files without the file extensions. For the
              PLplot built-in maps the possible values are: "globe" -- continental outlines  "usa"  --  USA  and
              state  boundaries  "cglobe"  --  continental  outlines  and  countries  "usaglobe"  --  USA, state
              boundaries and continental outlines

       minx (PLFLT(3plplot), input)
              The minimum x value of map elements to be drawn. The units must match the shapefile (built in maps
              are degrees lat/lon). Objects in the file which do not encroach on the box defined by minx,  maxx,
              miny,  maxy  will  not be rendered. But note this is simply an optimisation, not a clipping so for
              objects with some points inside the box and some points outside the box all  the  points  will  be
              rendered.  These parameters also define latitude and longitude wrapping for shapefiles using these
              units. Longitude points will be wrapped by integer multiples of 360 degrees to place them  in  the
              box.  This  allows  the  same data to be used on plots from -180-180 or 0-360 longitude ranges. In
              fact if you plot from -180-540 you will get two cycles of data drawn. The value of  minx  must  be
              less  than the value of maxx. Passing in a nan, max/-max floating point number or +/-infinity will
              case the bounding box from the shapefile to be used.

       maxx (PLFLT(3plplot), input)
              The maximum x value of map elements to be drawn - see minx.

       miny (PLFLT(3plplot), input)
              The minimum y value of map elements to be drawn - see minx.

       maxy (PLFLT(3plplot), input)
              The maximum y value of map elements to be drawn - see minx.

AUTHORS

       Many developers (who are credited at http://plplot.org/credits.php) have contributed to PLplot  over  its
       long history.

SEE ALSO

       PLplot documentation at http://plplot.org/documentation.php.

                                                   March, 2025                                    PLMAP(3plplot)