great-circle

I have two matrices, one is 200K rows long, the other is 20K. For each row (which is a point) in the first matrix, I am trying to find which row (also a point) in the second matrix is closest to the point in the first matrix. This is the first method that I tried on a sample dataset: #Test dataset pixels.latlon=cbind(runif(200000,min=-180, max=-120), runif(200000, min=50, max=85)) grwl.latlon=cbind(runif(20000,min=-180, max=-120), runif(20000, min=50, max=85)) #calculate the distance matrix library(geosphere) dist.matrix=distm(pixels.latlon, grwl.latlon, fun=distHaversine) #Pick out the

I need to get the distance from a lat/lng point to a line. Of course needs to follow the Great Circle. I found a great article on this at http://www.movable-type.co.uk/scripts/latlong.html but the code is not working right. Either I am doing something wrong or there is something missing. Here is the function in question. See the link for the other functions if needed. var R = 3961.3 LatLon.crossTrack = function(lat1, lon1, lat2, lon2, lat3, lon3) { var d13 = LatLon.distHaversine(lat1, lon1, lat3, lon3); var brng12 = LatLon.bearing(lat1, lon1, lat2, lon2); var brng13 = LatLon.bearing(lat1, lon1

I've taken some of the things I learned in a Flowing Data great circle mapping tutorial and combined them with code linked in the comments to prevent weird things from happening when R plots trans-equatorial great circles. That gives me this: airports <- read.csv("/home/geoff/Desktop/DissertationData/airports.csv", header=TRUE) flights <- read.csv("/home/geoff/Desktop/DissertationData/ATL.csv", header=TRUE, as.is=TRUE) library(maps) library(geosphere) checkDateLine <- function(l){ n<-0 k<-length(l) k<-k-1 for (j in 1:k){ n[j] <- l[j+1] - l[j] } n <- abs(n) m<-max(n, rm.na=TRUE) ifelse(m > 30,