Transfrom WGS84 (lat/lon) coordinates into Estonian Coordinate System

WGS84toECS.R

# Install dependencies if not present
deps <- c("ggmap", "sp", "rgdal", "XLConnect")
install.packages(deps)

for (dep in deps) {
  library(dep, character.only=TRUE)
}

# Read the data
xlsx.file <- "/home/jlehtoma/temp/Points to be converted.xlsx"
dat <- readWorksheetFromFile(xlsx.file, "Sheet1")

# df is a data frame holding the coords (in WGS84 lat-lon)
sp.dat <- SpatialPointsDataFrame(dat[, c("Longitude", "Latitude")], dat, 
                                 proj4string = CRS("+proj=longlat +datum=WGS84"))

# Spatial data is now in lat/lon, check coordinates on google map
map <- qmap(c(lon=mean(sp.dat$Longitude), lat=mean(sp.dat$Latitude)), 
            source="google", zoom=10)
map + geom_point(aes(x=Longitude, y=Latitude, colour=Population), data=dat, 
                 size=4)

# Estonian Coordinate System of 1997 (epsg:3301): http://bit.ly/104TO8u

# Project the spatial data to ECS
sp.data.ECS <- spTransform(sp.dat, CRS("+init=epsg:3301"))
# Write the data back to the original Excel file to a new worksheet 
# "ECS_coordinates"
writeWorksheetToFile(xlsx.file, sp.data.ECS, "ECS_coordinates")