Dear List,
I am using function distCosine from package geosphere to a list of lat/lon
coordinates, and I want to calculate the great circle distance between a
pair of coordinates in the list and all other pairs --- essentially, the
output should be a matrix. I have been able to achieve this with two nested
loops, as in the example below, but this is rather slow. Can someone please
suggest how to do this with "apply" or similar?
Many thanks,
Lara
install.packages("geosphere")
library(geosphere)
##generate sets of random points
n <- 100
lon <- runif(n, -180, 180)
lat <- runif(n, -90, 90)
#package geosphere
##spherical law of cosines method
dCos <- matrix( , nrow = length(lon), ncol = length(lat))
for (i in 1:length(lon)) {
for (j in 1:length(lat)) {
dCos[[i,j]] <- distCosine(matrix(c(lon[i], lat[i]), ncol=2), matrix(c(
lon[j], lat[j]), ncol=2))
}}
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