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.

                                            June, 2022                             PLMAP(3plplot)