RgoogleMaps (version 1.1.9.7)

PlotArrowsOnStaticMap: plots arrows or segments on map

Description

This function plots/overlays arrows or segments on a map.

Usage

PlotArrowsOnStaticMap(MyMap, lat0, lon0, lat1 = lat0, lon1 = lon0, TrueProj = TRUE, FUN = arrows, add = FALSE, verbose = 1,...)

Arguments

MyMap

map image returned from e.g. GetMap()

lat0, lon0

coordinates of points from which to draw.

lat1, lon1

coordinates of points to which to draw.

TrueProj

set to FALSE if you are willing to accept some degree of inaccuracy in the mapping. In that case, the coordinates of the image are in lat/lon and the user can simply overly points/lines/axis without worrying about projections

FUN

plotting function to use for overlay; typical choices would be arrows and segments

add

add to existing map ?

verbose

level of verbosity

...

further arguments passed to arrows or segments

Value

See Also

PlotOnStaticMap mypolygon

Examples

require(PBSmapping);
  shpFile <- paste(system.file(package = "RgoogleMaps"), "/shapes/bg11_d00.shp", sep = "")
  #shpFile <- system.file('bg11_d00.shp', package = "RgoogleMaps");
  
  shp=importShapefile(shpFile,projection="LL");
  bb <- qbbox(lat = shp[,"Y"], lon = shp[,"X"]);
  MyMap <- GetMap.bbox(bb$lonR, bb$latR, destfile = "DC.jpg");
  PlotPolysOnStaticMap(MyMap, shp, lwd=.5, col = rgb(0.25,0.25,0.25,0.025), add = F);

  #North Carolina SIDS data set:
  shpFile <- system.file("shapes/sids.shp", package="maptools");
  shp=importShapefile(shpFile,projection="LL");
  bb <- qbbox(lat = shp[,"Y"], lon = shp[,"X"]);
  MyMap <- GetMap.bbox(bb$lonR, bb$latR, destfile = "SIDS.jpg");
  #compute regularized SID rate
  sid <- 100*attr(shp, "PolyData")$SID74/(attr(shp, "PolyData")$BIR74+500)
  b <- as.integer(cut(sid, quantile(sid, seq(0,1,length=8)) ));
  b[is.na(b)] <- 1;
  opal <- col2rgb(grey.colors(7), alpha=TRUE)/255; opal["alpha",] <- 0.2;
  shp[,"col"] <- rgb(0.1,0.1,0.1,0.2);
  for (i in 1:length(b)) 
    shp[shp[,"PID"] == i,"col"] <- rgb(opal[1,b[i]],opal[2,b[i]],opal[3,b[i]],opal[4,b[i]]);
  PlotPolysOnStaticMap(MyMap, shp, lwd=.5, col = shp[,"col"], add = F);
  
  #compare the accuracy of this plot to a Google Map overlay:
  library(maptools);
  qk <- SpatialPointsDataFrame(as.data.frame(shp[, c("X","Y")]), as.data.frame(shp[, c("X","Y")]))
  proj4string(qk) <- CRS("+proj=longlat");
  tf <- "NC.counties";
  SGqk <- GE_SpatialGrid(qk)
  png(file=paste(tf, ".png", sep=""), width=SGqk$width, height=SGqk$height,
  bg="transparent")
  par(mar=c(0,0,0,0), xaxs="i", yaxs="i");par(mai = rep(0,4))
  plotPolys(shp, plt=NULL)
  dev.off()
  kmlOverlay(SGqk, paste(tf, ".kml", sep=""), paste(tf, ".png", sep=""));
  #This kml file can now be inspected in Google Earth or Google Maps
  
  #or choose an aspect ratio that corresponds better to North Carolina's elongated shape:
  MyMap <- GetMap.bbox(bb$lonR, bb$latR, destfile = "SIDS.jpg", size = c(640, 320), zoom = 7);
  PlotPolysOnStaticMap(MyMap, shp, lwd=.5, col = shp[,"col"], add = F);