Beautiful maps with R and Google Maps

It’s been awhile since I have posted on this blog. I have been caught up in the midst of publishing my thesis works as a book which is now available for at amazon and trying to be adventurous during the harsh but still exciting Norwegian winter.

A friend of mine asked me last week to help him plot locations of boreholes, that he is doing research on, to a decent map. I came up with a suggestion of creating it in R using Google Maps as a base map. Of course this could have been done easily and more aesthetically attractive using the conventional GIS softwares. It is more exciting and reproducible where the R script can be reused easily.

The location of the boreholes was originally recorded using gps in UTM coordinate format. Therefore, I used the spTransform method of rgdal package to convert them into latitudes and longitudes.  The rest of the codes are listed below.

	library(rgdal)
	library(RgoogleMaps)
	boreholes<- read.csv("boreholes.csv", sep=",", header=TRUE)
	bh_grd <- SpatialPoints(boreholes[,c("East","North")],
	proj4string=CRS("+proj=utm +zone=32 +datum=WGS84"))
	bholes<- SpatialPointsDataFrame(bh_grd,boreholes[,-c(2,3)])
	bholes<-bholes[,-c(2,3)]
	bh_geo<- spTransform(bholes, CRS("+proj=longlat +datum=WGS84"))
	North<-coordinates(bh_geo)[,2]
	East<-coordinates(bh_geo)[,1]
	bb <- qbbox(lat=range(North), lon=range(East))
	m <- c(mean(North), mean(North))
	zoom <- min(MaxZoom(latrange=bb$latR,lonrange=bb$lonR))
	Map <- GetMap.bbox(bb$lonR, bb$latR, zoom=zoom, maptype="mobile",
	NEWMAP=F, destfile="map.png", RETURNIMAGE=T);
	tmp <- PlotOnStaticMap(Map,lat=North, lon=East,
	cex=1.5,pch=20,col="red", add=F, verbose=0);
	tmp <- TextOnStaticMap(Map,lat=North, lon=East+.0007, cex=.8, font=4,
	col="black", labels= boreholes$Number, add=T, verbose=0);
	tmp <- PlotArrowsOnStaticMap(Map, lat0=min(North),lon0=max(East)+.006,
	lat1=min(North)+.0006,lon1=max(East)+.006,lwd=6,col="black",add=T);
	#Satellite image as a base map
	SMap <- GetMap.bbox(bb$lonR, bb$latR, zoom=zoom, maptype="satellite",
	NEWMAP=F, destfile="map.png", RETURNIMAGE=TRUE);
	tmp <- PlotOnStaticMap(SMap,lat=North, lon=East,
	cex=1.5,pch=20,col="red", add=F, verbose=0);
	tmp <- TextOnStaticMap(SMap,lat=North, lon=East+.0007, cex=.8, font=4,
	col="yellow", labels= boreholes$Number, add=T, verbose=0);
	tmp <- PlotArrowsOnStaticMap(SMap, lat0=min(North),lon0=max(East)+.006,
	lat1=min(North)+.0006,lon1=max(East)+.006,lwd=6,col="yellow",add=T);

view raw boreholes.R hosted with ❤ by GitHub