# Difference in coordinates to country conversion

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## Difference in coordinates to country conversion

 I have a set of coordinates at 1° x 1°  which look like this: structure(list(longitude = c(-179L, -178L, -177L, -177L, -177L, -176L), latitude = c(-15L, -15L, -14L, 51L, 52L, -22L)), .Names = c("longitude", "latitude"), row.names = c("1", "2", "3", "4", "5", "6"), class = "data.frame") I am trying to obtain country names for them and tried the following two methods. There are some difference (mostly between USA and Canada). While sometimes method 1 provides a country name but method 2 cannot. Is there a way to say if either of the methods are more accurate? Or another more accurate method? Or am I doing something wrong? Thanks! Sincerely, Shouro library(raster) library(tmap) library(rworldmap) library(countrycode) # Method 1 {   countriesSP <- getMap(resolution='low')   #countriesSP <- getMap(resolution='high') #you could use high res map from rworldxtra if you were concerned about detail   # convert our list of points to a SpatialPoints object   # pointsSP = SpatialPoints(points, proj4string=CRS(" +proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs +towgs84=0,0,0"))   #setting CRS directly to that from rworldmap   pointsSP = SpatialPoints(coord_dams, proj4string=CRS(proj4string(countriesSP)))   # use 'over' to get indices of the Polygons object containing each point   indices = over(pointsSP, countriesSP)   # return the ADMIN names of each country   indices\$ADMIN   #indices\$ISO3 # returns the ISO3 code   #indices\$continent   # returns the continent (6 continent model)   #indices\$REGION   # returns the continent (7 continent model) } # Method 2 pts_dams <- SpatialPoints(coord_dams,proj4string=CRS(proj4string(worldmap))) indices_dams <- over(pts_dams, worldmap,na.rm=TRUE) indices <- cbind(indices_dams, coord_dams) #Keep only ISO3, log, lat foo_dams<-indices[,c(3,12,13)]         [[alternative HTML version deleted]] _______________________________________________ R-sig-Geo mailing list [hidden email] https://stat.ethz.ch/mailman/listinfo/r-sig-geo