Plotting shapefiles on top of Google map tiles [closed]

Answer 1

From the developer, it seems to work nicely.

  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);