There are many pathways to this, but you could use a map projection that provides the properties you want and sample points there, then project that back to longitude latitude.
Here's a dummy example, I just found an equal area projection by stumbling through spatialreference.org, you should look into this more for your purposes. I use spsample in the sp package to generate the points, but what you use here really depends on what kind of points you want, I ignored land vs. sea but you could easily adapt this to the land only. library(maptools) data(wrld_simpl) w <- subset(wrld_simpl, NAME %in% c("Canada", "Mexico", "United States")) library(rgdal) proj <- "+proj=laea +lat_0=45 +lon_0=-100 +x_0=0 +y_0=0 +a=6370997 +b=6370997 +units=m +no_defs" w <- spTransform(subset(wrld_simpl, NAME %in% c("Canada", "Mexico", "United States")), CRS(proj)) ## create an extent object to sample from, rather than just the land ## (just use the "w" object if you want the points to be only on land) library(raster) bbpoly <- as(extent(w), "SpatialPolygons") proj4string(bbpoly) <- CRS(proj4string(w)) x <- spsample(bbpoly, n = 2000, type = "hexagonal") pts <- spTransform(x, CRS(proj4string(wrld_simpl))) plot(pts) plot(as(wrld_simpl, "SpatialLines"), add = TRUE, col = "dodgerblue") On Thu, Aug 29, 2013 at 3:27 AM, john d <dobzhan...@gmail.com> wrote: > Ok, I'll be more explicit :) > > If I want to generate random coordinates across North America by uniformly > sampling latitudes and longitudes, the geographical distance between these > coordinates would decrease towards higher latitudes. I'd like to be able to > generate coordinates (e.g. a grid) such that the geographical distances > between coordinates would be constant regardless of latitude. > > > > On Wed, Aug 28, 2013 at 12:04 PM, Barry Rowlingson < > b.rowling...@lancaster.ac.uk> wrote: > >> You will find that any two coordinates are equidistant from each other... >> >> So my suggestion is you need to expand you question a bit more! :) >> >> On Wed, Aug 28, 2013 at 3:49 PM, john d <dobzhan...@gmail.com> wrote: >> > Dear all, >> > >> > I need to generate coordinates that are equidistant, regardless of >> > latitude. Any suggestions? >> > >> > Thanks! >> > >> > John >> > >> > [[alternative HTML version deleted]] >> > >> > _______________________________________________ >> > R-sig-Geo mailing list >> > R-sig-Geo@r-project.org >> > https://stat.ethz.ch/mailman/listinfo/r-sig-geo >> > > [[alternative HTML version deleted]] > > _______________________________________________ > R-sig-Geo mailing list > R-sig-Geo@r-project.org > https://stat.ethz.ch/mailman/listinfo/r-sig-geo -- Michael Sumner Hobart, Australia e-mail: mdsum...@gmail.com _______________________________________________ R-sig-Geo mailing list R-sig-Geo@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-geo