PBSmapping (version 2.72.1)

importGSHHS: Import Data from a GSHHS Database

Description

Import data from a GSHHS database and convert data into a PolySet with a PolyData attribute.

Usage

importGSHHS(gshhsDB, xlim, ylim, maxLevel=4, n=0, useWest=FALSE)

Arguments

gshhsDB

path name to binary GSHHS database. If unspecified, looks for gshhs_f.b in the root of the PBSmapping library directory.

xlim

range of X-coordinates (for clipping). The range should be between 0 and 360.

ylim

range of Y-coordinates (for clipping).

maxLevel

maximum level of polygons to import: 1 (land), 2 (lakes on land), 3 (islands in lakes), or 4 (ponds on islands); ignored when importing lines.

n

minimum number of vertices that must exist in a line/polygon in order for it to be imported.

useWest

logical: if TRUE, convert the X-coordinates (longitude) to \(^\circ\)W (western hemisphere -180 to 0).

Value

A PolySet with a PolyData attribute.

Details

This routine requires a binary GSHHG (Global Self-consistent, Hierarchical, High-resolution Geography) database file. The GSHHG database has been released in the public domain and may be downloaded from http://www.soest.hawaii.edu/pwessel/gshhg/. At the time of writing, the most recent binary database was the archive file called gshhg-bin-2.3.4.zip.

The archive contains multiple binary files that contain geographical coordinates for shorelines (gshhs), rivers (wdb_rivers), and borders (wdb_borders). The latter two come from World DataBank II (WDBII): http://meta.wikimedia.org/wiki/Geographical_data#CIA_World_DataBank_II_and_derivates The five resolutions available are: full (f), high (h), intermediate (i), low (l), and coarse (c).

This routine returns a PolySet object with an associated PolyData attribute. The attribute contains four fields: (a) PID, (b) SID, (c) Level, and (d) Source. Each record corresponds to a line/polygon in the PolySet. The Level indicates the line's/polygon's level (1=land, 2=lake, 3=island, 4=pond). The Source identifies the data source (1=WVS, 0=CIA (WDBII)).

See Also

importEvents, importLocs, importPolys, importShapefile

Examples

# NOT RUN {
useWest=FALSE
useVers=c("2.2.0","2.2.3","2.3.0","2.3.4") # GSHHG versions
mapswitch = 5
for (i in c("land","rivers","borders"))
  if (exists(i)) eval(parse(text=paste0("rm(",i,")")))
switch( mapswitch,
 # 1. Canada------------------------------------------------
      {vN=4; useWest=T; xlim=c(-150,-50)+360;ylim=c(40,75)},
 # 2. NW Canada & America-----------------------------------
      {vN=4; useWest=T;xlim=c(-136,-100)+360;ylim=c(40,75)},
 # 3. Black Sea (user Ivailo)-------------------------------
      {vN=4; xlim=c(27.5, 34.3); ylim=c(40.9, 46.7)},
 # 4. W Europe, NW Africa (user Uli)------------------------
      {vN=4; xlim=c(-20,10); ylim=c(20,50)},
 # 5. W Europe + Iceland------------------------------------
      {vN=4; xlim=c(-25, 20); ylim=c(40, 68)},
 # 6. New Zealand-------------------------------------------
      {vN=4; xlim=c(163, 182); ylim=c(-48,-34)},
 # 7. Australia---------------------------------------------
      {vN=4; xlim=c(112,155); ylim=c(-44,-10)},
 # 8. Japan-------------------------------------------------
      {vN=4; xlim=c(127,148); ylim=c(30,47)},
 # 9. Central America---------------------------------------
      {vN=4; useWest=T; xlim=c(-95,-60)+360;ylim=c(-10,25)},
 #10. North Pacific-----------------------------------------
      {vN=4; useWest=T; xlim=c(150,220); ylim=c(45,80)},
 #11. Pacific Ocean-----------------------------------------
      {vN=4; xlim=c(112,240); ylim=c(-48,80)},
 #12. North Atlantic (world coordinates)--------------------
      {vN=4; xlim=c(285,360); ylim=c(40,68)},
 #13. North Atlantic (western hemisphere coordinates)-------
      {vN=4; xlim=c(-75,0); ylim=c(40,68)},
 #14. Atlantic Ocean----------------------------------------
      {vN=4; xlim=c(285,380); ylim=c(-50,68)},
 #15. Northern hemisphere-----------------------------------
      {vN=4; xlim=c(-180,180); ylim=c(0,85)},
 #16. Asia--------------------------------------------------
      {vN=4; xlim=c(0,180); ylim=c(0,80)},
 #17. North America-----------------------------------------
      {vN=4; xlim=c(-180,0); ylim=c(0,80)},
 #18. International date line-------------------------------
      {vN=4; xlim=c(45,315); ylim=c(0,80)},
 #19. Indian Ocean------------------------------------------
      {vN=4; xlim=c(20,130); ylim=c(-40,40)},
 #20. Moose County ("400 miles north of everywhere")--------
      {vN=4; xlim=c(272.5,280.5); ylim=c(43,47.5)}
)
db=paste0("gshhg-bin-",useVers[vN])        # database version folder
gshhg   = paste0("C:/Ruser/GSHHG/",db,"/") # directory with binary files
land    = importGSHHS(paste0(gshhg,"gshhs_i.b"),
          xlim=xlim,ylim=ylim,maxLevel=4,useWest=useWest)
rivers  = importGSHHS(paste0(gshhg,"wdb_rivers_i.b"),
          xlim=xlim,ylim=ylim,useWest=useWest)
borders = importGSHHS(paste0(gshhg,"wdb_borders_i.b"),
          xlim=xlim,ylim=ylim,useWest=useWest,maxLevel=1)
if(exists("land")){
  plotMap(land,xlim=xlim-ifelse(useWest,360,0),ylim=ylim,
    col="lemonchiffon",bg="aliceblue")
  if(!is.null(rivers)) addLines(rivers,col="blue")
  if(!is.null(borders)) addLines(borders,col="red",lwd=2)
}
# }